Jet engine components

For a single stage subsonic compressor, which of the following statements about the highest possible compressor pressure ratio (CPR) is correct?

• CPR of an axial compressor > CPR of centrifugal compressor

• CPR of an axial compressor < CPR of centrifugal compressor

• CPR of an axial compressor = CPR of centrifugal compressor

• CPR of any value can be attained with either an axial or a centrifugal compressor

The maximum gas flow rate that can be handled by a multistage axial compressor at a given rotational speed is dictated by

• Compressor surge

• Rotating stall

• Choking

• Optimum design pressure ratio

For a completely subsonic isentropic flow through a convergent nozzle, which of the following statement is TRUE?

• Pressure at the nozzle exit > back pressure

• Pressure at the nozzle exit < back pressure

• Pressure at the nozzle exit = back pressure

• Pressure at the nozzle exit = total pressure

A combustor is operating with a fuel-air ratio of 0.03. If the stoichiometric fuel-air ratio of the fuel used is 0.06, the equivalence ratio of the combustor will be ______ (accurate to two decimal places).

• 2.00

• 0.50

• 0.20

• 0.05

The stoichiometric fuel-to-air ratio in an aircraft engine combustor varies with the compressor pressure ratio as follows:

• Increases linearly

• Decreases linearly

• Is independent

• Increases nonlinearly

What is the value of fuel-air ratio?

• 0.0018

• 0.018

• 0.18

• 1.18

What is the value of total pressure ratio across the stage? (Note: Give answer as a whole number)

The value of the nozzle exit pressure in Pascal is (Note: give the answer with three decimal places)

In the vane-less space between the impeller and the diffuser vanes in a centrifugal compressor, the angular momentum varies in the following manner in the radial direction

• Increases

• Decreases

• Remains constant

• First increases and then decreases

The isentropic efficiency of the turbine stage is ______% (round off to two decimal places).

• 87.89

• 89.89

• 85.89

• 90.00