Ventury Effect; Scientific Explanation of Laws and Dynamics
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Transcript of Ventury Effect; Scientific Explanation of Laws and Dynamics
Venturi Effect
Its Role in Maritime Ops.
What is it?
Reduction in fluid pressure that results when fluid flows through a constricted section of pipe.
Velocity of fluid increases as cross-sectional area decreases as static pressure correspondingly decreasing; Jet effect.
Named after Giovanni Battista Venturi (1746–1822 ) Italian physicist.
Workings
“Fluid velocity must increase as it passes through a constriction to satisfy
principles of continuity while its pressure must decrease to
satisfy the principle of conservation of mechanical
energy; Gain in kinetic energy in a fluid may accrue due to its increased velocity
though constriction is regated by a drop in
pressure.” Laws of Fluid Dynamics.
When a fluid such as water flows through a tube that narrows to a smaller diameter and partial restrictions cause a higher pressure at the inlet than the narrow end. Pressure difference causes the fluid to accelerate towards the low pressure narrow section in which it maintains a higher speed.
Choked Flow
Limiting case of Venturi effect: When fluid reaches state of choked flow where
the fluid velocity approaches the local speed of sound. In choked flow, the mass flow rate will not increase with a
further decrease in the downstream pressure
environment. Mass flow rate for a compressible fluid can
increase with increased upstream pressure which will
increase density of fluid through constriction; velocity
remains constant.
Uses and Presence
Cargo eductor/ejector on oil product and chemical tankers.
Flue gas scrubbers. Ventilators Emptying bilge water from
moving boats via hull waste gate; air pressure inside being greater than water.
Dredging
Summary
Reduction in fluid pressure that results when a fluid flows through constricted section of a pipe.