Fundamentals of Turbomachines — Summer 2022

Define turbomachine. Name the turbomachines used in Aircraft engines.

Differentiate between axial compressor and centrifugal compressor.

Draw h-s diagram for an axial turbine stage.

How the energy transfer is taking place in turbomachines?

Differentiate between reciprocating machines and turbomachines.

Draw h-s diagram of a radial turbine stage with diffuser.

Derive the expression for utilization factor for a fifty percent reaction axial turbine stage.

Explain the phenomenon of choking in centrifugal compressor.

With neat sketch explain the essential parts of a centrifugal compressor.

Acentrifugal compressor gave the following data: rotational speed 11,500 rpm, inlet total head temperature 21ºC, outlet and inlet total head pressure 4 bar and 1 bar respectively, impeller diameter 75cm and slip factor 0.92. calculate the compressor efficiency.

Define degree of reaction. Justify that for a fifty percent reaction stage enthalpy change through rotor and stator are same.

What are the three types of blade shapes possible in centrifugal compressor rotor?

What is slip factor? Explain the Stodola’s formula to determine the slip factor.

How the aerodynamic losses are occurred in turbomachines?

With a neat sketch, discuss secondary flow in a cascade of blades.

Draw velocity triangle of an axial compressor stage and derive the expression of work consumed by compressor.

How stall is propagated in a compressor blade row.

Write a note on surging in axial compressor stage.

Explain the following performance coefficients. Flow coefficient, rotor pressure flow coefficient, rotor enthalpy loss coefficient, diffuser pressure loss coefficient, diffuser enthalpy loss coefficient and loading coefficient.1

Why multistage of turbomachines is required in jet engines?

Write the general matching procedure for a single spool turbojet engine.

Draw velocity diagram of a two-stage axial turbine stage with maximum utilization factor and derive the general expression of work done for multistage turbines.

Explain the conditions for zero percent reaction stage and hundred percent reaction stage.

What is match point? Which are the assumptions to consider to match turbomachines?

Write the steps to find equilibrium point in a turbojet engine.