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2nd YEAR FLUIDS / COMPRESSIBLE FLOW

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3. COMPRESSIBLE FLOW

CONTENTS

 

3.1 INTRODUCTION

3.2 SPEED OF SOUND

3.3 ISENTROPIC FLOW

3.4 NORMAL SHOCK WAVES

3.5 TWO-DIMENSIONAL WAVES


3.1   INTRODUCTION

- IN LIQUIDS, THE EFFECTS OF PRESSURE ON DENSITY ARE SMALL ENOUGH TO BE CONSIDERED INSIGNIFICANT. LIQUID FLOWS ARE CONSEQUENTLY INCOMPRESSIBLE FLOWS.

- FOR GASES, THE IDEAL GAS EQUATION, P = RT, SHOWS THAT PRESSURE CAN HAVE SUBSTANTIAL EFFECTS ON DENSITY.

- THUS GAS FLOWS WHICH INVOLVE LARGE PRESSURE CHANGES, WILL ALSO INVOLVE CHANGES IN DENSITY AND WOULD BE COMPRESSIBLE FLOWS.

- CHANGES IN DENSITY WILL THEN THROUGH CONTINUITY, m = A U, CAUSE FURTHER CHANGES IN THE FLUID VELOCITY.

 

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