Question

In axial flow compressor, exit flow angle deviation from the blade angle is a function of 
1. blade camber
2. blade camber and incidence angle
3. space-chord ratio 
4. blade camber and space-chord ratio

Answer 1

Correct Answer - Option 2 : blade camber and incidence angle

Concept:

Axial flow compressor: It is made up of multiple stages of rotating and stationary blades (or stators), through which air is drawn in parallel to the axis of rotation and incrementally compressed as it passes through each stage.

Based on the operation condition and the design philosophy, there might be a difference between the camber and flow angle at the leading edge, which is called the incidence angle.

The difference between the blade camber angle and the flow angle at the exit is termed the deviation angle.

Blade camber: The blade inlet angle α₁ is the angle formed by the line drawn tangent to the forward end of the camber line and the axis of compressor. The blade outlet angle α₂ is the angle of a line drawn tangent to rear of the camber line. Subtracting α₂ from α₁ gives camber angle (θ).    

From above, the exit flow angle deviation from the blade angle is a function of blade camber and incidence angle.