A Short Diffuser With Low Pressure Loss

Abstract

A new design concept for gas turbine diffusers is presented and its potential verified by experimental data. The data were obtained from a series of research diffusers, both tubular and annular, with a range of area ratios from approximately 1.9:1 to 3.2:1 and with diffuser entry Mach number and velocity-profile distortion levels which simulated those encountered in engine systems. Measurements for all conditions tested are successfully correlated. From the correlations it is predicted that, in an engine, a pressure recovery in excess of 80 percent may be obtained with diffuser lengths only one-third that required by current design techniques, providing a bleed-off rate of approximately 3 percent of the main airflow can be tolerated at the diffuser throat. It is suggested that the bleedoff will be suitable for turbine cooling purposes.