Session: 32-04 Low Pressure Turbines 1

Paper Number: 125061

125061 - Experimental Investigation Into the Generation Mechanisms of Additional Loss due to Incoming Wakes in Low-Pressure Turbine Cascades 

For low-pressure (LP) turbines, the aerodynamic performance is largely determined by the profile loss. In addition to the profile loss, there exists the loss due to incoming wakes, whose magnitude is sometimes comparable to the profile loss. For a substantial improvement in LP turbine performance, it is necessary to reduce not only the profile loss but also the additional loss. This paper aims at clarifying the generation mechanisms of additional loss so that a design guide for reducing the additional loss is introduced. A parametric set of boundary layer measurements was conducted using a low-speed linear turbine cascade test with a moving-bar mechanism for blades with no separation bubble on the suction surface. Four different wake-passing frequencies and three different Reynolds numbers were examined. From the boundary layer measurements, the streamwise variations of the boundary layer integral parameters were obtained along the rear part of the blade surfaces. Also, the wall-normal profiles of root-mean-square of streamwise velocity fluctuation was obtained at each boundary layer measurement location. One of the sources of additional loss, wake-boundary layer interaction loss, was derived by using the measured boundary layer integral parameters together with the estimated profile loss under each flow condition. It was found that the wake-boundary layer interaction loss was attributed to the breakdown of Klebanoff streaks generated in the suction surface boundary layer and the magnitude of the loss was determined by the wake-passing frequency.

Presenting Author: Hidekazu Kodama Iwate University

Presenting Author Biography: Degrees
Doctor of Engineering, Kyusyu University, 1999.
Master of Engineering, Kyusyu University, 1977.
B.S. in Aeronautics, Kyusyu University, 1975.

Experience
Retired, Fellow of IHI Corporation, 2017
Visiting Professor of Iwate University, 2018
Retired, Visiting Professor of Iwate University, 2023

Authors:

Hidekazu Kodama Iwate University
Ken-Ichi Funazaki Iwate University