suggests a shock model for double circular arc blades in which blades pitch defines shock condition there. In fact, these spaces determine angles by which supersonic flow turns to suction surface of blades where the flow is tangent to the surface: the less space (increasing solidity), the lower shock loss. In this condition, as flow enters to passage between two blades, its velocity is increased due to expansion compatible with PrandtlMayer relation [10], then in the passage entrance
at point B (Fig. 1) a bow shock is created whose extension is ex-
Similar to subsonic state, the best fits for graphs, suggested by [2] to estimate shock loss, were obtained by Mathematica, then their equations were used in computer program in order to measure flow condition at intended locations. Eq. (1) has also been used to estimate θ by regard to cascades specifications.
2.2. Methodology to estimate structural limitations
Centrifugal stress at rotor blades roots influences stage pres- sure ratio. This factor is a function of rotor rotational speed, and thus crucial in this study.
[2] suggests following equation to measure critical centrifugal stress:
tended to front of leading edge of neighboring blade at point C.