New Correlations of the Two-Dimensional Turbine Cascade Aerodynamic Performance
Journal of Engineering for Power
Theoretical evaluation and experimental research have been conducted to verify the performance of steam and gas turbines, including exhaust turbines of superchargers. The simplified channel method and hydroelectrical analog method have been used to calculate blade surface velocity distribution. Based on the 'fully developed turbulence" assumption, viscous effects are approximately taken into account by using the boundary layer theory. Theoretical optimum profile loss coefficients are given.
... cts of velocity profile on losses are analyzed. Turbine cascades have the characteristics of high solidity, high setting angle and high air turning angle, which facilitate the use of the channel concept. On this basis, K.M. Todd's 'passage convergent gradient, " modified O. Zweifel's "tangential load coefficient" and other effective criteria have been chosen and cascade data correlated. Some relatively accurate semi-empirical formulas for predicting the aerodynamic performance of cascades are formulated. N0:dE NC LATURE All angles are measured from cascade axis. b airfoil chord 0 = 0, 0, P p assage 5 assage gradient i=p"-p, incidence angle K=I -(S 7 zi 3 l passage convergence 1= b aspect ratio Op length of passage centerline between inlet and outlet throats M = a Mach number critical velocity ratio Or , 0 z passage inlet throat and outlet throat rr r r2 leading edge radius and trailing edge radius = t cascade solidity Re = Wb Reynolds number kinematic viscosity t = t pitch-chord ratio To initial turbulence of overtaking flow