HYDRAULIC BEHAVIOUR OF SUPERCAVITATED FLOW

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HYDRAULIC BEHAVIOUR OF SUPERCAVITATED FLOW
Presentation By Shelly Sharma Supervisors Roger
Hughes Lu Aye
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CONTENTS

• INTRODUCTION
• OBJECTIVES
• LITERATURE REVIEW
• MATHEMATICAL ANALYSIS
• EXPERIMENTAL WORK
• CONCLUSIONS

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INTRODUCTIONCavitation v/s Supercavitation
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Present Applications

• Russian Shkval Torpedoes (50 m/s)
• Under Water Jetting (14 m/s)

Supercavitation in Pipe
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OBJECTIVES

• PART I
• Development of hydraulic theory using acoustics
• Determination of hydrodynamic theory
• PART II
• Altering flow to get energy into the system
• For a Supercavitated Flow

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• Instabilities at Interface

• Surface gravity waves
• Rayleigh-Taylor instability
• Kelvin-Helmholtz instability
• Jeans instability
• Thermal instability

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MATHEMATICAL MODELLING

• Basic Model

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Structure
Dispersion equation
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Results
TIME
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Circular Pipe (incorporating momentum change)
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Results
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Acoustics at Interface
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Structure
Dispersion equation
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Proposed Techniques

• Funnel shaped Orifices

• Pumps
• Ribbing inside of the pipe
• Air-vapor mixture

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Water Jet Through Orifice
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EXPERIMENTAL WORK
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CONCLUSIONS

• Vapor-water interface will not lead to
  Kelvin-Helmholtz instability which otherwise will
  be there in air-water interface
• Waves at vapor-water interface propagate in
  direction of flow and grow with time
• Instability grows rapidly as thickness of layers
  become equal
• An orifice can be used to cause supercavitation
  in pipe flow
• Unstable jet is formed which keeps fluctuating
• Various types of nozzles can be used to change
  characteristics of jet
• Air-water mixture may be used as supercavitating
  layer

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THANK YOU