Compressible Flow (Part I)

The speed of sound in an ideal gas depends on?

Note: You may select more than one option.

• √T, where T is absolute temperature.

• √T, where T is temperature in degree Celcius.

• √k, where k is the specific heat ratio.

• √R, where R is the gas constant.

Which of the following is incorrect for an airfoil moving at a speed less than the speed of sound, c?

• The upstream fluid can sense that the airfoil is coming

• There is a smooth flow over the airfoil

• A shock wave is formed by nature

• The pressure disturbances are attenuated over a distance Δt(c-V)

Which of the following is correct for a doppler effect?

• The source is moving faster than the speed of sound.

• The observer at A will detect a sound pulse frequency that is higher than the frequency emitted by the moving sound source

• The observer at A will not detect the sound source until the source has passed

What type of flow occurs when the Mach number is greater than one?

• Transonic flow

• Sonic flow

• Supersonic flow

• Hypersonic flow

What does the T_total in the Mach number relation mean?

• The temperature recognised by the thermometer moving with the flowing fluid

• The temperature that would arise if the fluid velocity were brought to zero

• The temperature of the fluid as it undergoes a change in elevation