ISI-1b hj,

Fluids Engineering

Experimental Aerodynamic Characteristics of a Compound Wing in Ground Effect

Saeed Jamei1

Marine Technology Center, Faculty of Mechanical Engineering, Universiti Teknologi Malaysia (UTM) Skudai 81310, Johor, Malaysia. Tel.: +60 75535957 E-mail: [email protected], [email protected] Adi Maimun Abdul Malek Marine Technology Center, Faculty of Mechanical Engineering, Universiti TeknologiMalaysia (UTM), Skudai 81310, Johor, Malaysia. Tel.: +60 755 35707 E-mail: [email protected] Shuhaimi Mansor Department of Aeronautical Engineering, Faculty of Mechanical Engineering, Universiti TeknologiMalaysia (UTM), Skudai 81310, Johor, Malaysia. Tel.: +60 75535845 E-mail: [email protected] Nor Azwadi Che Sidik Department of Thermo Fluids, Faculty of Mechanical Engineering, Universiti TeknologiMalaysia (UTM), Skudai 81310, Johor, Malaysia. Tel.: +60 75534718 E-mail: [email protected] 1

Saeed Jamei, Marine Technology Center, Universiti Teknologi Malaysia (UTM), [email protected]

Journal of Fluids Engineering. Received February 17, 2013; Accepted manuscript posted January 31, 2014. doi:10.1115/1.4026618 Copyright (c) 2014 by ASME

Acce

pted

Man

uscr

ipt N

ot C

opye

dite

d

Downloaded From: http://fluidsengineering.asmedigitalcollection.asme.org/ on 07/09/2014 Terms of Use: http://asme.org/terms

Fluids Engineering

Agoes Priyanto Tel.: +60 75534744 Marine Technology Center, Faculty of Mechanical Engineering, Universiti TeknologiMalaysia (UTM), Skudai 81310, Johor, Malaysia. Tel.: +60 75534744 E-mail: [email protected] ABSTRACT

Wing configuration is a parameter that affects the performance of wing-in-

ground effect (WIG) craft. In this study, the aerodynamic characteristics of a new

compound wing were investigated during ground effect. The compound wing was

divided into three parts with a rectangular wing in the middle and two reverse taper

wings with anhedral angle at the sides. The sectional profile of the wing model is

NACA6409. The experiments on the compound wing and the rectangular wing were

carried to examine different ground clearances, angles of attacks and Reynolds

numbers. The aerodynamic coefficients of the compound wing were compared with

those of the rectangular wing, which had an acceptable increase in its lift coefficient at

small ground clearances and its drag coefficient decreased compared to rectangular

wing at a wide range of ground clearances, angle of attacks and Reynolds numbers.

Furthermore, the lift to drag ratio of the compound wing improved considerably at small

ground clearances. However, this improvement decreased at higher ground clearance.

The drag polar of the compound wing showed the increment of lift coefficient versus of

drag coefficient was higher especially at small ground clearances. The Reynolds number


Acce

pted

Man

uscr

ipt N

ot C

opye

dite

d


Fluids Engineering

had a gradual effect on lift and drag coefficients and also lift to drag of both wings.

Generally, the nose down pitching moment of the compound wing was found smaller

but it was greater at high angle of attack and Reynolds number for all ground clearance.

The center of pressure was closer to the leading edge of the wing in contrast to the

rectangular wing. However, the center of pressure of the compound wing was later to

the leading edge at high ground clearance, angle of attack and Reynolds number.

KEYWORDS: Aerodynamic characteristics; Compound wing; Wind tunnel; Wing-in-ground effect.

INTRODUCTION

The idea of using ground effect to improve lift was introduced as early as 1930. Initial

experimental and computational techniques used special body shapes in ground

proximity to calculate lift and more information can be found in the references [1-3].

The results included pressure distribution and lift coefficients for any shape in two or

three dimensional bodies [4, 5]. There are several review papers on different WIG crafts

that discuss their performance and design conception [6, 7]. Many researchers have

worked to develop WIG crafts that could fly near the ground. Initial research in the

development of WIG crafts was carried out in Finland, Russia, Sweden and the United

States. Ollila (1980) [6] wrote a paper that reviewed experimental and proposed designs

over the course of time. Another paper, which investigated the history and development

of WIG crafts, was written by Rozhdesvensky [8]. Many countries are currently working

on WIG crafts because of the advantages of these crafts offer in terms of fuel economy


Acce

pted

Man

uscr

ipt N

ot C

opye

dite

d


Fluids Engineering

and high travel speeds when compared to other water transport vehicles. The study

reviews the experimental and theoretical configuration of WIG crafts used, which

improve the aerodynamic performance. Lift was improved when the flow of air

underneath the wing body and around stagnation point on the pressure surface (lower

surface of body) was trapped. This created high pressure on the lower surfaces and low

pressures on the upper surfaces and provided a high lifting force (Ram effect).

Research into the influence of ground effect on streamline around the wings

began in the 1920s [9, 10]. Rozhdestvensky [11] described the flow of air over the

airfoils at different edges including the leading, trailing and side edge. Airflow can be

streamlined by reducing the downwash angle that causes the efficient angle of attack to

rise. This will improve the lift force and reduce drag force. Wieselsberger [12] used

Prandtls Lifting Line theory to develop the aerodynamic characteristics required by

airplanes for takeoff and landing. His numerical results agreed with the experimental

data. As a result, longer landing strips for airplanes were introduced to take advantage

of existing dynamic air cushions under the wings. The wind tunnel investigations

conducted by Recant [13] showed that ground effect does not affect maximum lift but

flaps do cause a reduction in the maximum lift in proximity to the ground.

Chawla et al. [14] employed a moveable flap, detachable end and center plates

in the wind tunnel test for their wing model. They showed that the wing experienced

ground effect at ground clearances (h/c) below 1. The influence of endplate on the lift to


Acce

pted

Man

uscr

ipt N

ot C

opye

dite

d


Fluids Engineering

drag ratio was higher at lower ground clearances. Ahmed and Goonaratne [15] studied

the growing lift of thick airfoils with small aspect ratios (AR). They found that there was

a relationship between lift and drag coefficients with respect to increasing angles of

attack. For example, the lift coefficient increased and drag coefficient decreased when

the wing reached a 2 angle of attack of for various angles of flap. Ahmed [16]

investigated the influence of camber on performance of different airfoils. He discovered

an acceleration of flow, at the rate of 50% and 30%, occurring on NACA 4415 and NACA

0015 airfoils. The lowest level of acceleration was for the NACA 6415 airfoil because of

low suction on its upper surface. The intensity of turbulence over NACA 0015 airfoil at

low ground clearance was greater than other NACA airfoils. Ahmed illustrated the

narrow wake region and small turbulence intensity behind the trailing edge of NACA

6415. He also showed the development of a boundary layer on thick airfoils that left the

suction surface at the trailing edge and reattached to the ground surface near the

trailing edge of airfoils at small ground clearances. This phenomenon caused a

substantial reduction in velocity and subsequently a large dropping momentum, which

increased the turbulence intensity. The reduction of velocity and rising of turbulence

intensity was increased when the angle of attack was increased. The reattachment of

the boundary layer did not appear at higher ground clearances.

Ahmed et al. [17] studied the aerodynamic characteristics of NACA4412 airfoil

sections in a low turbulence wind tunnel with a moving ground model. They measured

the pressure distribution, velocity and wake region of the flow over the airfoil surface,


Acce

pted

Man

uscr

ipt N

ot C

opye

dite

d


Fluids Engineering

lift and drag forces. A reduction of suction on the upper surface was shown when the

airfoil approached the ground for all pitch angles. For a small angle of attack (

Fluids Engineering

SIMPLE algorithm for the coupling of velocity and pressure were used in the finite

volume method. The moving ground was used to better demonstrate ground effect.

Based on the theory of flat-plate flow [21] the y+ on wing was estimated around 100 as

shown below in Equation 2.

y+ = 0.172 (y/l) Re0.9 (2)

where y and Re are the height of first mesh on wing and local Reynolds number of flow,

respectively. The incompressible flow was assumed according to its Mach number of

0.1.

Using a Canard wing as a replacement for a tail wing is an alternative design

parameter used for creating stability in WIG craft [22, 23]. Li et al. [23] showed that the

Canard wing caused the aerodynamic center to shift to the leading edge of the main

wing without changing the relationship between the centers. This is an advantage when

locating the center of gravity. The weak point of the Canard wing was reported on

height stability, although it behaved well in terms of pitching stability. Li et al.

established that the drag force of a Canard wing was less than tail wing that caused

higher efficiency for WIG crafts. Lee et al. [24] examined the aerodynamic characteristics

of rectangular wings with anhedral angles and endplates when different angles of attack

and ground clearances were used. Three configurations were examined, clean wing,

wing with endplate and wing with anhedral angle. The lift to drag ratio of wing with

anhedral angle was in the middle and its height static stability performed satisfactorily

for all angles of attack and ground clearances. They explained that the variations of lift


Acce

pted

Man

uscr

ipt N

ot C

opye

dite

d


Fluids Engineering

coefficient for wings with anhedral angle versus Reynolds numbers was the smallest and

the drag coefficient was the largest when compared to other models.

Wing planforms are a challenge when designing WIG craft [25, 26]. Yang et al.

[25] analyzed two different WIG craft configurations. One of the configurations used an

airplane concept and another configuration used the Lippisch concept. The main wing of

airplane concept was a rectangular wing and a reverse forward swept wing was used for

the Lippisch concept craft. In terms of aerodynamic forces and static height stability,

they found that the performance and stability of the Lippisch concept WIG craft was

better than the airplane concept WIG craft. A higher lift coefficient and lower drag

coefficient were found for the Lippisch concept craft at different ground clearances and

angles of attack. In terms of pressure distribution and the wing planform, the tip vortex

of the airplane type craft was stronger. The Lippisch concept WIG craft could fly in and

out of ground effect with acceptable height static stability. Yang [27] et al. showed that

the aerodynamic centers of Forward Swept (FS) Wings and Reversed Forward Swept

(RFS) Wings were nearer to the leading edge of the wings unlike the aerodynamic center

of a rectangular wing. The performance (L/D) of rectangular wings was lower than the

RFS wing but greater than the FS wing in terms of extreme ground effect. They revealed

the static stability of the 3D model of the wings was higher than 2D model. They also

illustrated that endplates were not suitable for static height stability because they

moved towards 2D with increased ground clearance.


Acce

pted

Man

uscr

ipt N

ot C

opye

dite

d


Fluids Engineering

Wing configuration is the greatest challenge facing researchers attempting to

improve aerodynamic behavior by finding the optimal configuration for wings in terms

of ground effect. Several concepts have been tried, such as flap, endplate, and multi-

element wings. The aim has been to bring about improvement by modifying the

performance of WIG crafts by increasing their flight range and reducing their

environmental impact. This paper experimentally investigated the aerodynamic

characteristics of a new compound wing configuration in terms of ground effect, which

this wing has numerically examined by Jamei et al [28]. This compound wing was

composed of three parts; a rectangular wing in the middle and two reverse taper wings

with an anhedral angle at each side. Increasing the aerodynamic performance of the

wing is the main idea. In this study, two wings were used in wind tunnel test, a

compound wing and a rectangular wing. The tests were performed to examine different

ground clearances, angles of attacks and Reynolds numbers. The results, such as lift and

drag coefficients, lift to drag ratio, pitching moment and centre of pressure of the

compound wing were compared with the rectangular wing results.

WIND TUNNEL

The aerodynamic characteristics, specifically the ground effect, of the new compound

wing were investigated in a low speed wind tunnel at the Universiti Teknologi Malaysia

(UTM-LST). This wind tunnel was able to deliver a maximum airspeed of 80 m/s (160

knots or 288 km/hr) inside the test section. The size of test section was 2.0 meters wide,

1.5 meters height, and 5.5 meters long. The flow inside the wind tunnel was of good


Acce

pted

Man

uscr

ipt N

ot C

opye

dite

d


Fluids Engineering

quality, with a flow uniformity < 0.15%, temperature uniformity < 0.2%, flow angularity

uniformity < 0.15%, and turbulence < 0.06%. UTM-LST had high-quality facilities that

allow for accuracy and repeatability of experiment results.

The size of test model and the magnitude of the force measurements required

that the wind tunnel was equipped with different balance systems for measuring

aerodynamic forces and moments. In this study, a JR3-50M31A3 sensor was used for

force measurements. This sensor is a 6- axis force and toque transducer with internal

electronics. The diameter of the sensor was 50 mm and it was 31 mm thick. The

capacities of this sensor are shown in Table 1.

WING MODEL

The experiments were carried out on a rectangular and a compound wing as shown in

Figure 1. The compound wing was composed of three parts; a rectangular wing in the

middle and two reverse taper wings with an anhedral angle at the sides. The NACA 6409

airfoil section was selected because it suitable for low speed flights when the airspeed

was between 25.5-40 m/s. The principal dimensions of both wings are shown in Figure 2

and summarized in Table 2.


Acce

pted

Man

uscr

ipt N

ot C

opye

dite

d


Fluids Engineering

EXPERIMENTAL PROCEDURES AND SET-UP

In the wind tunnel, aerodynamic force measurements were carried out for a range of

ground clearances (h/c) and angles of attacks (), from h/c= 0.015 to h/c= 0.405 and

from = 0 to = 10. Ground clearance (h/c) was defined as the distance ratio between

the wing trailing edge center and ground surface (h) to root chord length (c) of the wing.

The range of the angles of attack is small because of touching wing to ground for some

ground clearances.

In this study, the floor of wind tunnel was used as a fixed flat ground as shown in

Figure 3. The wing was mounted in the test section of the wind tunnel with a strut

(Figure 3). The position of the strut was at the quarter-chord length from the leading

edge of the wings. The strut was adjusted and then the height of the wings was fixed at

the ground clearances. The wing could rotate about an axis at the quarter-chord length

from the leading edge of wings.

The Frontal area ratio wing and test section was small, resulting in a negligible

blockage ratio for the wings related to side and roof walls of the wind tunnel. In this

study, all experiments were performed with three freestream velocities, 25.5, 30 and 40

m/s. Based on theses freestream velocities and the chord length of the wings (c) the

correspond Reynolds numbers (Re) were 0.349106, 0.41110

6, 0.54810

6, respectively.


Acce

pted

Man

uscr

ipt N

ot C

opye

dite

d


Fluids Engineering

REPEATABILITY OF THE EXPERIMENT

One way to check the setup of the model and accuracy of the data is to repeat the

experiment. Figure 4 shows the lift and drag coefficients of two different occurrences of

the model and wind tunnel test under the same conditions present at the Universiti

Teknologi Malaysia low speed wind tunnel (UTM-LST). As shown below, there was an

acceptable level of repeatability for this experiment.

COMPARISON OF AERODYNAMIC COEFFICIENTS BETWEEN COMPOUND AND RECTANGULAR WINGS

Figures 5-10 show comparisons of aerodynamic coefficients of the rectangular and the

compound wings respect to the ground clearance (h/c), angle of attack () and

Reynolds number (Re).

Lift Coefficient

The lift coefficient of the rectangular wing and the compound wing are shown in Figure

5. The lift coefficient of the compound wing was substantial higher than the lift

coefficient of the rectangular wing at a low ground clearance of 0.1 for an angle of

attacks of 4 as a shown in Figure 5 a-c. At small angle of attack resulted in a lower lift

coefficient for the compound wing but this was not a drawback because the angle of

incidence in WIG crafts is greater than 4. When the ground clearance increased, the

difference between rectangular and compound wing lift coefficients decreased. There


Acce

pted

Man

uscr

ipt N

ot C

opye

dite

d


Fluids Engineering

was a slightly higher lift coefficient for the rectangular wing at ground clearance of

h/c0.2 (Figure 5 g-p) that means at high ground clearance had more effect on lift

coefficient. The compound wing configuration had a higher ram pressure at low ground

clearance as compared with rectangular wing. This creates an advantage for WIG craft

water takeoffs by reducing the hydrodynamic resistance because there is higher lift and

then wetted surface of WIG craft hull decreased. There was an increment in lift

coefficient for both types of wings when ground clearance decreased but this increment

was higher for the compound wing. Figure 5 shows that the lift coefficient was

enhanced when the Reynolds numbers had a higher value at all ground clearances. In

most cases, varying the Reynolds numbers had little effect on the gap between the lift

coefficients of the rectangular and the compound wings.

Drag Coefficient

The great advantage of a compound wing configuration is related to its drag coefficient.

Figure 6 illustrates that the drag coefficient of the compound wing was lower than the

drag coefficient of the rectangular wing at all ground levels and Reynolds numbers. This

reduction of drag was associated with the smaller distance between the wingtip and the

ground and a smaller wingtip cross section area, which created a weaker tip vortex. The

reduction of drag on the compound wing as compared with rectangular wing became

more beneficial at lower ground levels and angles of attack of 2 (Figure 6 a-i). The

distance between the plots of the wings reduced when the ground clearance


Acce

pted

Man

uscr

ipt N

ot C

opye

dite

d


Fluids Engineering

augmented because the effects of side parts of the compound wing reduced (Figure 6 j-

p). The drag coefficient of both wings dropped when the wings approached the ground.

According to the drag coefficient plots, power requirement and then fuel consumption

of WIG craft with the compound wing will reduce. Both wings experienced a slight

reduction in drag coefficient when the Reynolds numbers increased because the friction

drag, due to the viscose effect in higher Reynolds numbers, was smaller. Typically, the

gap between the drag coefficient of rectangular and compound wings were reduced

with increments of Reynolds number at all ground clearances.

Lift to Drag Ratio

The most important performance parameter for a wing is defined by its lift to drag ratio

(L/D). The efficiency of a wing is referred to its lift to drag ratio. The comparison of lift to

drag ratio between the rectangular and the compound wing is shown in Figure 7. The lift to

drag ratio for both wings was enhanced when the ground level dropped. The lift to drag

ratio of the compound wing increased considerably compared to the rectangular wing at

low ground clearances of 0.1and 0.15 for all Reynolds numbers (Figure 7 a-f). The lift to drag

ratio of the compound wing was moderately augmented at a ground clearance of 0.2 and an

angle of attack of approximately >2 (Figure 7 g-i). The angle of incidence in WIG crafts is

greater than 4 then at this ground clearance level, the performance of the compound

wing still improved. However, the performance of compound wing had nor more

increment at higher ground clearances (h/c=0.3) as shown in Figure 7 m-p. Also, at free


Acce

pted

Man

uscr

ipt N

ot C

opye

dite

d


Fluids Engineering

stream (ground clearance around 1.5), angle of attack of 4 and Re1, the lift to drag ratio

was recorded around 5.2 and 6 for the compound wing and the rectangular wing

respectively, these magnitudes were near the plots of Figure 7m that could be explained

the advantages of the compound wing exits at ground clearance lower than 0.3. Figure 7

reveals the increase in Reynolds number created by a gradual enhancement of lift to

drag ratio for both compound and rectangular wings for all ground clearances. The gap

between the plots of wings has small variation respect to Reynolds numbers. The effect

of Reynolds number was higher for both wings at lower ground clearances (Figure 7 a-f).

Drag Polar

The correlation between the drag coefficient and the lift coefficient is called the drag

polar. Figure 8 a-f (h/c0.15) shows the average drag polar plots for the compound

wing, which was noticeable upper than the drag polar plots for the rectangular wing.

This meant that for certain drag coefficients the lift coefficient for the compound wing

was higher. The gap between the rectangular and the compound wing decreased rapidly

especially at ground clearances greater than 0.15 (Figure 8 g-p). The increment of

Reynolds number made a slight shifting up on drag polar plots of both wings. However,

the distance between the plots of wings generally reduced when Reynolds number

enhanced.


Acce

pted

Man

uscr

ipt N

ot C

opye

dite

d


Fluids Engineering

Moment Coefficient

The pitching moment is a parameter that affects the longitudinal stability of WIG crafts.

The moment coefficient for the compound and rectangular wings is shown in Figure 9.

Figure 9 shows that there was a steady reduction in the moment coefficient for both

wings when the height dropped, although there was an increase in the moment

coefficient at high angles of attack and high Reynolds numbers that could be because

changes of pressure distributions on the surface of the wings (Figure 9 c, f, i, l, p). At a

low ground clearance of 0.1 (Figure 9 a-c) the different between the plots of the

rectangular and the compound wing was small, while for higher ground levels, the

moment coefficient of the rectangular wing was slight greater that of the compound

wing. However, the moment coefficient of the compound wing was greater than that of

the rectangular wing in high Reynolds numbers and high angles of attack (Figure 9 c, f, i,

l, p). At all ground clearances, slope of the plots of both wings averagely decreased

when Reynolds number enhanced where it was negative for the rectangular wing at

high Reynolds number and ground clearances of 0.25 and 0.3 (Figure 9 l, p).The moment

coefficients of both wings decreased slightly when the Reynolds numbers increased, but

this reduction was larger at high ground clearances especially for the rectangular wing

(Figure 9 l, p). Generally, the gap between the plots of both wing gradually decreased

respect to increment of Reynolds number.


Acce

pted

Man

uscr

ipt N

ot C

opye

dite

d


Fluids Engineering

Centre of Pressure

The center of pressure of the wing is another parameter that plays an important role in

the longitudinal stability of WIG crafts. The distance between the leading edge and

center of pressure on the wing is defined as Xcp. Figure 10 shows the center of pressure

position for the rectangular and the compound wing. In general, the position of center

pressure of compound wing was a little nearer to leading edge, compared to the

rectangular wing, except at ground clearance greater than 0.15 and high Reynolds

numbers where the center of pressure of the rectangular wing was nearer to leading

edge (Figure 10 i, l, p) . The center of pressure for both wings moved slightly to the

leading edge as the Reynolds numbers increased, especially for angles of attack of

greater than 6. Typically, the center of pressure shifts to the leading edge as ground

clearance is reduced, however at high Reynolds numbers (Re3) and ground clearances

greater than 0.15, this center shifted to trailing edge. The gap between the plots of both

wings commonly had slight reduction versus Reynolds number.

CONCLUSION

This study experimentally investigated the aerodynamic characteristics of a new ram

wing concept called a compound wing. The compound wing was composed of three

parts. The middle part was a rectangular wing and two side parts were reverse taper

wings with an anhedral angle. Based on the experimental force measurements, the lift

coefficient for the compound wing improved at low ground clearance compared to the


Acce

pted

Man

uscr

ipt N

ot C

opye

dite

d


Fluids Engineering

rectangular wing, which can decrease takeoff distance. The anhedral angle of a

compound wing shifts the stagnation point towards the lower side of the wing and

modifies the pressure distribution on the pressure surface leading to a higher

augmentation in lift force at low ground clearances. The drag coefficient of the

compound wing was reduced compared to the rectangular wing, especially for low

ground clearances. The distance between the wing tip of the compound wing and

ground was smaller which meant that the tip vortex and downwash velocity were

weaker. Consequently, the induced drag of the compound wing decreased. According to

lift and drag force, the lift to drag ratio for the compound wing was enhanced for a wide

range of ground clearances. The substantial improvement in lift to drag ratio for the

compound wing in extreme ground effect identifies it a good performing and efficient

WIG craft. The moment coefficient of the compound wing was smaller than for the

rectangular wing, although at a high angle of attack and Reynolds number, the moment

coefficient for the compound wing was greater. Comparably, the center of pressure for

the compound wing shifted slightly towards the leading edge, which can affect the

longitudinal stability of a WIG craft. A suitable tail out of the ground effect is one

method to modify the longitudinal stability of WIG craft. In the future, an investigation

into the aerodynamic characteristics of a complete WIG craft model will be tested in the

UTM wind tunnel.

ACKNOWLEDGMENTS The authors would like to thank the Ministry of Science, Technology, and Innovation

(MOSTI) Malaysia for funding this research.


Acce

pted

Man

uscr

ipt N

ot C

opye

dite

d


Fluids Engineering

NOMENCLATURE a anhedral angle

b wing Span

bm middle wing span

c chord length

ct tip chord length

CL lift Coefficient

CD drag Coefficient

D drag Force

h height of trailing edge above the ground

h/c ground clearance

l characteristics length

L lift force

L/D lift to drag ratio

Re Reynolds number

XCP center of pressure

y height of first mesh

y+ non-dimensional wall distance

angle of attack

taper ratio (c/ ct)


Acce

pted

Man

uscr

ipt N

ot C

opye

dite

d


Fluids Engineering

REFERENCES [1] Davis, J. E., and Harris G. L., 1973, Nonplanar wings in nonplanar ground effect, Journal of Aircraft, 10(5), pp. 308-312.

[2] Barrows, T. M., 1973, The ram air cushion-advanced fluid suspension for tracked levitated vehicles, ASME Paper No. 73-ICT 14. [3] Widnall, S. E., and Barrows, T. M., 1970, An analytic solution for two and three dimensional wings in ground effect, Journal of Fluid Mechanics, 41(4), pp. 769-792. [4] Rubbert, P. E., and Saaris, G. R., 1972, Review and evaluation of a three-dimensional lifting potential flow analysis method for arbitrary configurations, AIAA Paper 72-188.

[5] Johnson, F. T., and Rubbert, P. E., 1975, Advanced panel-type influence coefficient methods applied to subsonic flow, AIAA Paper 75-50. [6] Ollila, R. G., 1980, Historical review of WIG vehicles, Journal of Hydrodynamics, 14(3), pp. 65-76. [7] Ando, S., 1990, Critical review of design philosophies for recent transport WIG effect vehicles, Trans. Japan Society for Aeronautical and Space Sciences, 33(99), pp. 28-40.

[8] Rozhdestvensky, K. V., 2006, Wing-in-ground effect vehicles, Journal of Aerospace Science, 42, pp. 211-283. [9] Raymond, A., 1921, Ground influence on airfoils, NAC Technical Note 67. [10] Reid, E., 1927, A full scale investigation of ground effect, NACA Technical Report 265. [11] Rozhdestvensky, K. V., 2000, Aerodynamics of a lifting system in extreme ground effect, 1st edition, Springer-Verlag. [12] Wieselsberger, C., 1922, Wing resistance near the ground, NACA TM. 77. [13] Recant, I. G., 1939, Wing-tunnel investigation of ground effect on wing with flaps, NACA TN. 705. [14] Chawla, M. D., Edwards, L. C., and Franke, M. E., 1990, Wind-tunnel investigation of wing-in-ground effect, Journal of Aircraft, 27(4), pp. 289-293. [15] Ahmed, N., and Goonaratne, J., 2002, Lift augmentation of a low-aspect-ratio thick wing in ground effect, Journal of Aircraft, 39(2), pp. 381-384.


Acce

pted

Man

uscr

ipt N

ot C

opye

dite

d


Fluids Engineering

[16] Ahmed M. R., 2004, Flow over thick airfoils in ground effect- an investigation on the influence of camber, proc. 24th International Congress of the Aeronautical Sciences, 29 August- 3 September, Yokohama, Japan, pp. 1-10. [17] Ahmed, M. R., Takasaki, T., and Kohama, Y., 2007, Aerodynamic of NACA4412 airfoil in ground effect, AIAA Journal, 45(1), pp. 37-47.

[18] Fink, M. P., and Lastinger, J. L., 1961, Aerodynamic characteristics of low-aspect-ratio wings in close proximity to the ground, NASA TN D 926. [19] Carter, A. W., 1961, Effect of ground proximity on the aerodynamic characteristics of aspect-ratio 1 airfoils with and without endplate, NASA TN D 970. [20] Abramowski, T., 2007, Numerical investigation of airfoil in ground proximity, Journal of Theoretical and Applied Mechanics, 45(2), pp. 425-436. [21] Schlichting, H., 1968, Boundary Layer Theory, New-York: McGraw-Hill. [22] Li, Y., Yang, W., and Yang. Z., 2010, Numerical study on wing in ground effect of canard configuration, Aeronautical Computing Technique, 40(4), pp. 27-30. [23] Li, Y., Yang, W., and Yang. Z., 2010, Numerical study on static longitudinal stability of canard wig craft, Flight Dynamics, 28(1), pp. 9-12. [24] Lee, J., Han, C. S., and Bae, C. H., 2010, Influence of wing configurations on aerodynamic characteristics of wings in ground effect, Journal of Aircraft, 47(3), pp. 1030-1040. [25] Yang, Z., Yang, W., and Li, Y., 2009, Analysis of two configurations for a commercial wig craft based on CFD, Proc. 27th AIAA Applied Aerodynamics Conference, 22 - 25 June, San Antonio, Texas, pp.1-9.

[26] Ying, C., Yang, W., and Yang, Z., 2010, Numerical simulation on reverse forward swept wing in ground effect, Computer Aided Engineering, 19(3), pp. 35-39. [27] Yang, W., Yang, Z., and Ying, C., 2010, Effects of design parameters on longitudinal static stability for wig craft, International journal of Aerodynamics, 1(1), pp. 97-113. [28] Jamei, S., Maimun, A., Mansor, S., and Azwadi, N., and Priyanto, A., 2012, Numerical Investigation on Aerodynamic Characteristics of a Compound Wing in Ground Effect, Journal of Aircraft, 49(5), pp. 1297-1305.


Acce

pted

Man

uscr

ipt N

ot C

opye

dite

d


Fluids Engineering

Figure Captions List

Fig. 1 (a) Rectangular wing and (b) Compound wing

Fig. 2 Sketch of (a) Rectangular wing and (b) Compound wing

Fig. 3 Experimental setup in the low speed wind tunnel at the Universiti

Teknologi Malaysia

Fig. 4 Repeatability of experimental test (a) Lift coefficient and (b) drag

coefficient

Fig. 5 Lift coefficient of rectangular and compound wing versus angle of attack

() for different ground clearances (h/c) and Reynolds number (Re)

Fig. 6 Drag coefficient of rectangular and compound wing versus angle of attack

() for different ground clearances (h/c) and Reynolds numbers (Re)

Fig.7 Lift to drag ratio of rectangular and compound wing versus angle of attack

() for different ground clearances (h/c) and Reynolds number (Re)

Fig. 8 Drag polar of rectangular and compound wing for different ground

clearances (h/c) and Reynolds number (Re)

Fig. 9 Moment coefficient of rectangular and compound wing versus angle of

attack () for different ground clearances (h/c) and Reynolds numbers

(Re)

Fig. 10 Center of pressure of rectangular and compound wings versus angle of

attack () for different ground clearances (h/c) and Reynolds numbers

(Re)


Acce

pted

Man

uscr

ipt N

ot C

opye

dite

d


Fluids Engineering

Table Caption List

Table 1 Load capacities of JR3 sensor

Table 2 Principal dimensions of the wings


Acce

pted

Man

uscr

ipt N

ot C

opye

dite

d


Fluids Engineering

(a)

(b)

Fig. 1 (a) Rectangular wing and (b) Compound wing


Acce

pted

Man

uscr

ipt N

ot C

opye

dite

d


Fluids Engineering

(a)

(b)

Fig. 2 Sketch of (a) Rectangular wing and (b) Compound wing


Acce

pted

Man

uscr

ipt N

ot C

opye

dite

d


Fluids Engineering

Fig. 3 Experimental setup in the low speed wind tunnel at the Universiti Teknologi Malaysia


Acce

pted

Man

uscr

ipt N

ot C

opye

dite

d


Fluids Engineering

0.00

0.10

0.20

0.30

0.40

0.50

0.60

0 2 4 6 8 10

Angle of attack

CL

(a)

0.00

0.01

0.02

0.03

0.04

0.05

0 2 4 6 8 10

Angle of attack

CD

(b)

Fig. 4 Repeatability of experimental test (a) Lift coefficient and (b) drag coefficient


Acce

pted

Man

uscr

ipt N

ot C

opye

dite

d


Fluids Engineering

0.00

0.10

0.20

0.30

0.40

0.50

0.60

0.70

0 2 4 6 8 10 12

CL

Rectangular wing

Compound wing

0.00

0.10

0.20

0.30

0.40

0.50

0.60

0.70

0 2 4 6 8 10 12

C

L

Rectangular wing

Compound wing

0.00

0.10

0.20

0.30

0.40

0.50

0.60

0.70

0 2 4 6 8 10 12

CL

Rectangular wing

Compound wing

(a) Re1, h/c=0.1 (b) Re2, h/c=0.1 (c) Re3, h/c=0.1


Acce

pted

Man

uscr

ipt N

ot C

opye

dite

d


Fluids Engineering

0.00

0.10

0.20

0.30

0.40

0.50

0.60

0.70

0 2 4 6 8 10 12

CL

Rectangular wing

Compound wing

0.00

0.10

0.20

0.30

0.40

0.50

0.60

0.70

0 2 4 6 8 10 12

CL

Rectangular wing

Compound wing

0.00

0.10

0.20

0.30

0.40

0.50

0.60

0.70

0 2 4 6 8 10 12

CL

Rectangular wing

Compound wing

(d) Re1, h/c=0.15 (e) Re2, h/c=0.15 (f) Re3, h/c=0.15


Acce

pted

Man

uscr

ipt N

ot C

opye

dite

d


Fluids Engineering

0.00

0.10

0.20

0.30

0.40

0.50

0.60

0.70

0 2 4 6 8 10 12

CL

Rectangular wing

Compound wing

0.00

0.10

0.20

0.30

0.40

0.50

0.60

0.70

0 2 4 6 8 10 12

CL

Rectangular wing

Compound wing

0.00

0.10

0.20

0.30

0.40

0.50

0.60

0.70

0 2 4 6 8 10 12

CL

Rectangular wing

Compound wing

(g) Re1, h/c=0.20 (h) Re2, h/c=0.20 (i) Re3, h/c=0.20


Acce

pted

Man

uscr

ipt N

ot C

opye

dite

d


Fluids Engineering

0.00

0.10

0.20

0.30

0.40

0.50

0.60

0.70

0 2 4 6 8 10 12

CL

Rectangular wing

Compound wing

0.00

0.10

0.20

0.30

0.40

0.50

0.60

0.70

0 2 4 6 8 10 12

CL

Rectangular wing

Compound wing

0.00

0.10

0.20

0.30

0.40

0.50

0.60

0.70

0 2 4 6 8 10 12

CL

Rectangular wing

Compound wing

(j) Re1, h/c=0.25 (k) Re2, h/c=0.25 (l) Re3, h/c=0.25


Acce

pted

Man

uscr

ipt N

ot C

opye

dite

d


Fluids Engineering

0.00

0.10

0.20

0.30

0.40

0.50

0.60

0.70

0 2 4 6 8 10 12

CL

Rectangular wing

Compound wing

0.00

0.10

0.20

0.30

0.40

0.50

0.60

0.70

0 2 4 6 8 10 12

CL

Rectangular wing

Compound wing

0.00

0.10

0.20

0.30

0.40

0.50

0.60

0.70

0 2 4 6 8 10 12

CL

Rectangular wing

Compound wing

(m) Re1, h/c=0.3 (n) Re2, h/c=0.3 (p) Re3, h/c=0.3

Fig. 5 Lift coefficient of rectangular and compound wing versus angle of attack () for different ground clearances (h/c) and Reynolds number (Re)


Acce

pted

Man

uscr

ipt N

ot C

opye

dite

d


Fluids Engineering

0.00

0.01

0.02

0.03

0.04

0.05

0.06

0.07

0.08

0.09

0.10

0 2 4 6 8 10 12

CD

Rectangular wing

Compound wing

0.00

0.01

0.02

0.03

0.04

0.05

0.06

0.07

0.08

0.09

0.10

0 2 4 6 8 10 12

CD

Rectangular wing

Compound wing

0.00

0.01

0.02

0.03

0.04

0.05

0.06

0.07

0.08

0.09

0.10

0 2 4 6 8 10 12

CD

Rectangular wing

Compound wing



Acce

pted

Man

uscr

ipt N

ot C

opye

dite

d


Fluids Engineering

0.00

0.01

0.02

0.03

0.04

0.05

0.06

0.07

0.08

0.09

0.10

0 2 4 6 8 10 12

CD

Rectangular wing

Compound wing

0.00

0.01

0.02

0.03

0.04

0.05

0.06

0.07

0.08

0.09

0.10

0 2 4 6 8 10 12

CD

Rectangular wing

Compound wing

0.00

0.01

0.02

0.03

0.04

0.05

0.06

0.07

0.08

0.09

0.10

0 2 4 6 8 10 12

CD

Rectangular wing

Compound wing


Fig. 6 Drag coefficient of rectangular and compound wing versus angle of attack () for different ground clearances (h/c) and Reynolds numbers (Re)


Acce

pted

Man

uscr

ipt N

ot C

opye

dite

d


Fluids Engineering

0

2

4

6

8

10

12

14

0 2 4 6 8 10 12

L/D

Rectangular wing

Compound wing

0

2

4

6

8

10

12

14

0 2 4 6 8 10 12

L/D

Rectangular wing

Compound wing

0

2

4

6

8

10

12

14

0 2 4 6 8 10 12

L/D

Rectangular wing

Compound wing



Acce

pted

Man

uscr

ipt N

ot C

opye

dite

d


Fluids Engineering

0

2

4

6

8

10

12

14

0 2 4 6 8 10 12

L/D

Rectangular wing

Compound wing

0

2

4

6

8

10

12

14

0 2 4 6 8 10 12

L/D

Rectangular wing

Compound wing

0

2

4

6

8

10

12

14

0 2 4 6 8 10 12

L/D

Rectangular wing

Compound wing


Fig.7 Lift to drag ratio of rectangular and compound wing versus angle of attack () for different ground clearances (h/c) and Reynolds number (Re)


Acce

pted

Man

uscr

ipt N

ot C

opye

dite

d


Fluids Engineering

0.00

0.10

0.20

0.30

0.40

0.50

0.60

0.70

0.00 0.02 0.04 0.06 0.08 0.10

CD

CL

Rectangular wing

Compound wing

0.00

0.10

0.20

0.30

0.40

0.50

0.60

0.70

0.00 0.02 0.04 0.06 0.08 0.10

CD

CL

Rectangular wing

Compound wing

0.00

0.10

0.20

0.30

0.40

0.50

0.60

0.70

0.00 0.02 0.04 0.06 0.08 0.10

CD

CL

Rectangular wing

Compound wing



Acce

pted

Man

uscr

ipt N

ot C

opye

dite

d


Fluids Engineering

0.00

0.10

0.20

0.30

0.40

0.50

0.60

0.70

0.00 0.02 0.04 0.06 0.08 0.10

CD

CL

Rectangular wing

Compound wing0.00

0.10

0.20

0.30

0.40

0.50

0.60

0.70

0.00 0.02 0.04 0.06 0.08 0.10

CD

CL

Rectangular wing

Compound wing0.00

0.10

0.20

0.30

0.40

0.50

0.60

0.70

0.00 0.02 0.04 0.06 0.08 0.10

CD

CL

Rectangular wing

Compound wing



Acce

pted

Man

uscr

ipt N

ot C

opye

dite

d


Fluids Engineering

0.00

0.10

0.20

0.30

0.40

0.50

0.60

0.70

0.00 0.02 0.04 0.06 0.08 0.10

CD

CL

Rectangular wing

Compound wing

0.00

0.10

0.20

0.30

0.40

0.50

0.60

0.70

0.00 0.02 0.04 0.06 0.08 0.10

CD

CL

Rectangular wing

Compound wing

0.00

0.10

0.20

0.30

0.40

0.50

0.60

0.70

0.00 0.02 0.04 0.06 0.08 0.10

CD

CL

Rectangular wing

Compound wing



Acce

pted

Man

uscr

ipt N

ot C

opye

dite

d


Fluids Engineering

0.00

0.10

0.20

0.30

0.40

0.50

0.60

0.70

0.00 0.02 0.04 0.06 0.08 0.10

CD

CL

Rectangular wing

Compound wing

0.00

0.10

0.20

0.30

0.40

0.50

0.60

0.70

0.00 0.02 0.04 0.06 0.08 0.10

CD

CL

Rectangular wing

Compound wing

0.00

0.10

0.20

0.30

0.40

0.50

0.60

0.70

0.00 0.02 0.04 0.06 0.08 0.10

CD

CL

Rectangular wing

Compound wing


Fig. 8 Drag polar of rectangular and compound wing for different ground clearances (h/c) and Reynolds number (Re)


Acce

pted

Man

uscr

ipt N

ot C

opye

dite

d


Fluids Engineering

0.00

0.01

0.02

0.03

0.04

0.05

0.06

0.07

0.08

0.09

0.10

0 2 4 6 8 10 12

CM

Rectangular wing

Compound wing

0.00

0.01

0.02

0.03

0.04

0.05

0.06

0.07

0.08

0.09

0.10

0 2 4 6 8 10 12

CM

Rectangular wing

Compound wing

0.00

0.01

0.02

0.03

0.04

0.05

0.06

0.07

0.08

0.09

0.10

0 2 4 6 8 10 12

CM

Rectangular wing

Compound wing



Acce

pted

Man

uscr

ipt N

ot C

opye

dite

d


Fluids Engineering

0.00

0.01

0.02

0.03

0.04

0.05

0.06

0.07

0.08

0.09

0.10

0 2 4 6 8 10 12

CM

Rectangular wing

Compound wing

0.00

0.01

0.02

0.03

0.04

0.05

0.06

0.07

0.08

0.09

0.10

0 2 4 6 8 10 12

CM

Rectangular wing

Compound wing

0.00

0.01

0.02

0.03

0.04

0.05

0.06

0.07

0.08

0.09

0.10

0 2 4 6 8 10 12

CM

Rectangular wing

Compound wing


Fig. 9 Moment coefficient of rectangular and compound wing versus angle of attack () for different ground clearances (h/c) and Reynolds numbers (Re)


Acce

pted

Man

uscr

ipt N

ot C

opye

dite

d


Fluids Engineering

0.00

0.10

0.20

0.30

0.40

0.50

0.60

0.70

0.80

0 2 4 6 8 10 12

XC

P/c

Rectangular wing

Compound wing

0.00

0.10

0.20

0.30

0.40

0.50

0.60

0.70

0.80

0 2 4 6 8 10 12

XC

P/c

Rectangular wing

Compound wing

0.00

0.10

0.20

0.30

0.40

0.50

0.60

0.70

0.80

0 2 4 6 8 10 12

XC

P/c

Rectangular wing

Compound wing



Acce

pted

Man

uscr

ipt N

ot C

opye

dite

d


Fluids Engineering

0.00

0.10

0.20

0.30

0.40

0.50

0.60

0.70

0.80

0 2 4 6 8 10 12

XC

P/c

Rectangular wing

Compound wing

0.00

0.10

0.20

0.30

0.40

0.50

0.60

0.70

0.80

0 2 4 6 8 10 12

XC

P/c

Rectangular wing

Compound wing

0.00

0.10

0.20

0.30

0.40

0.50

0.60

0.70

0.80

0 2 4 6 8 10 12

XC

P/c

Rectangular wing

Compound wing


Fig. 10 Center of pressure of rectangular and compound wings versus angle of attack () for different ground clearances (h/c) and Reynolds numbers (Re)


Acce

pted

Man

uscr

ipt N

ot C

opye

dite

d


Fluids Engineering

Table 1 Load capacities of JR3 sensor

Fx Fy Fz Mx My Mz

100 N 100 N 200 N 5 N-m 5 N-m 5 N-m


Acce

pted

Man

uscr

ipt N

ot C

opye

dite

d


Fluids Engineering

Table 2 Principal dimensions of the wings

Dimension Rectangular wing Compound wing

Total wing span (b) 25 cm 25 cm

Root chord length (c) 20 cm 20 cm

Middle wing span ( bm) - 12.5 cm

Taper ratio ( = c/ ct) - 1.25

Anhedral angle (a) - 13


Acce

pted

Man

uscr

ipt N

ot C

opye

dite

d


ISI-1b hj,

Documents

Transcript of ISI-1b hj,