question_answer

In an axial flow compressor design, velocity diagrams are constructed from the experimental data of aerofoil cascades. Which one of the, following statements in this regard is correct?

A) Incidence angle of the approaching air is measured from the trailing edge of the blade

B) \[\delta \] Is the deviation angle between the, angle of incidence and tangent to the amber line

C) The deflection of the gas steam while passing through the cascade is given by \[\varepsilon ={{\alpha }_{1}}-{{\alpha }_{2}}\]

D) \[\varepsilon \] Is the sum of the angle of incidence and camber less any deviation angle, i.e. \[\varepsilon =i+\theta -\delta \]