Aswan Presentation 2
23
COMPARISON STUDY OF SUPERCAVITATION PHENOMENA ON DIFFERENT PROJECTILES SHAPES IN TRANSIENT FLOW BY CFD Prof. Magdy Abu Rayan Mechanical Power Department, Mansoura University, Egypt Prof. Nabil H. Mostafa Mechanical Power Department, University, Zagazig, Egypt Dr. Mohamed H. Mansour Mechanical Power Department, Mansoura University, Egypt Eng. Mohsen Y. Mansour Aeronautical Eng., Mansoura University, Egypt 1
description
supercavitation
Transcript of Aswan Presentation 2
COMPARISON STUDY OF SUPERCAVITATION PHENOMENA ON
DIFFERENT PROJECTILES SHAPES IN TRANSIENT FLOW BY CFD
Prof. Magdy Abu Rayan
Mechanical Power Department, Mansoura
University, Egypt
Prof. Nabil H. Mostafa
Mechanical Power Department, University,
Zagazig, Egypt
Dr. Mohamed H. Mansour
Mechanical Power Department, Mansoura
University, Egypt
Eng. Mohsen Y. Mansour
Aeronautical Eng., Mansoura University,
Egypt
1
CAVITATION
2
• Cavitation is the occurrence
of vapor in a fluid due to
local low pressures which
are generated by high local
flow velocities. (Hammit,
1970)
SUPERAVITATION DEFINITION
Supercavitation is the use of cavitation effects to create a bubble of gas inside a liquid large enough to encompass an object travelling through the liquid. (Mostafa, 2000)
3
Supercavitation Formation 1. First, a cavity starts to grow at
the wake of the body.
2. Secondly, another cavity grows beside the nose while the cavity at the body wake continues to grow.
3. The nose cavity grows enough and the cavity at body wake starts to collapse.
4. the cavity beside the nose grows enough to merge with the cavity at the body wake forming a large one.
5. Finally, that cavity starts to fluctuate around the final. (Mostafa, 2000)
4
CAVITATION NUMBER
5
σ = (pr - pv) / (1/2 ρ v2)
where
σ= Cavitation number
pr = reference pressure (Pa)
pv = vapor pressure of the fluid (Pa)
ρ = density of the fluid (kg/m3)
v = velocity of fluid (m/s)
6
Grids over the four projectiles
1- Hemispherical
2- Telescopic
3- Blunt
4- Conical
7
FLOW SIMULATION UPON PROJECTILES
1-a- Hemispherical Using Structured Grid
Supercavitating cavities formation upon hemisphrical
projectile at speed 60 m/s, using structured mesh
domain, at t=1400x10-5 sec.
8
FLOW SIMULATION UPON PROJECTILES
1-b- Hemispherical, Unstructured
Supercavitating cavities formation upon hemisphrical
projectile at speed 60 m/s, using unstructured mesh domain.
9
FLOW SIMULATION UPON PROJECTILES
2-b- Telescopic, Structured
Supercavitating cavities formation upon telescopic
projectile at speed 60 m/s, using structured mesh
domain.
10
FLOW SIMULATION UPON PROJECTILES
2-b- Telescopic, Unstructured
Supercavitating cavities formation upon telescopic projectile at speed 60 m/s, using unstructured mesh domain.
11
FLOW SIMULATION FOR BLUNT PROJECTILE
3-a- Blunt, Structured
Supercavitating cavities formation upon blunt projectile at speed 60 m/s, using structured mesh domain.
12
FLOW SIMULATION FOR BLUNT PROJECTILE
3-b- Blunt, Unstructured
Supercavitating cavities formation upon blunt projectile at speed 60 m/s, using unstructured mesh domain.
13
FLOW SIMULATION UPON PROJECTILES
4-a- Conical, Structured
Supercavitating cavities formation upon blunt projectile
at speed 60 m/s, using structured mesh domain.
14
FLOW SIMULATION UPON PROJECTILES
4-b- Conical, Unstructured
Supercavitating cavities formation upon conical projectile at speed 60 m/s, using unstructured mesh domain.
15
FLOW SIMULATION UPON PROJECTILES
1-a- Hemispherical Using Structured Grid
Supercavitating cavities formation upon hemisphrical projectile at speed 60 m/s, using structured mesh domain.
16
FLOW SIMULATION UPON PROJECTILES
1-b- Hemispherical, Unstructured
Supercavitating cavities formation upon hemisphrical
projectile at speed 60 m/s, using unstructured mesh domain.
17
FLOW SIMULATION UPON PROJECTILES
2-b- Telescopic, Structured
Supercavitating cavities formation upon telescopic projectile at speed 60 m/s, using structured mesh domain.
18
FLOW SIMULATION UPON PROJECTILES
2-b- Telescopic, Unstructured
Supercavitating cavities formation upon telescopic projectile at speed 60 m/s, using unstructured mesh domain.
19
FLOW SIMULATION FOR BLUNT PROJECTILE
3-a- Blunt, Structured
Supercavitating cavities formation upon blunt projectile at speed 60 m/s, using structured mesh domain.
20
FLOW SIMULATION FOR BLUNT PROJECTILE
3-b- Blunt, Unstructured
Supercavitating cavities formation upon blunt projectile at speed 60 m/s, using unstructured mesh domain.
21
FLOW SIMULATION UPON PROJECTILES
4-a- Conical, Structured
Supercavitating cavities formation upon blunt projectile
at speed 60 m/s, using structured mesh domain.
22
FLOW SIMULATION UPON PROJECTILES
4-b- Conical, Unstructured
Supercavitating cavities formation upon conical projectile at speed 60 m/s, using unstructured mesh domain.
23
