Accession Number:

ADP006211

Title:

Transonic Blade Design on Rotational Stream Surfaces,

Descriptive Note:

Corporate Author:

STUTTGART UNIV (GERMANY F R)

Personal Author(s):

Report Date:

1987-09-01

Pagination or Media Count:

11.0

Abstract:

A method enabling the computation of cascade profiles from prescribed velocity distributions in a relative system is presented. The optimisation of the velocity distribution to attain definite values in parameters such as turning angle, chord length or profile thickness is also included. Comparisons between the inverse design method with various analysis programs for cascades in both absolute and relative systems show good agreement. High pressure ratios and mass flow rates are prerequisites to increase power density in turbomachines. The resulting high velocities with steep gradients between suction and pressure sides of the blades lead to supercritical flows with local supersonic regions. To avoid losses due to boundary layer separation which frequently appears with shocks in the decelerated region, a careful blade profiling is of utmost importance. In the sonic region, small changes of the profile contour lead to large changes in the velocity distribution thus making well known analysis methods laborious due to the many iterations. It is more effective to prescribe velocity distributions, which can be optimised by boundary layer methods for low losses, and to use an inverse computation procedure that delivers that appropriate profile contour. Only a few methods 4,5,6 exist for transonic flows.

Subject Categories:

  • Helicopters
  • Fluid Mechanics

Distribution Statement:

APPROVED FOR PUBLIC RELEASE