Session: 35-01 CFD Analyses

Paper Number: 80951

80951 - The Influences of Trailing Edge Base Pressure on the Profile Loss of Low-Pressure Turbine Blades 

The profile loss of a low-pressure turbine (LPT) blade consists of the losses due to the development of the blade surface boundary layers and the trailing edge losses associated with the effects of the trailing edge thickness. In the design of airfoil, the geometry is selected to minimize these losses. The knowledge of the pressure at the base of the trailing edge (base pressure) is important for the prediction of the trailing edge losses. It is known that base pressure varies with a surface velocity profile and a Reynolds number, and that a lower base pressure increases the losses, and a higher base pressure decreases the losses. However, in the airfoil design, it is difficult to predict the base pressure. This is because the physical mechanism to determine the base pressure level is not well understood. The reliability of loss minimization design is impaired by the uncertainty of base pressure. It is necessary to study how the base pressure level is determined from an airfoil geometry and a cascade flow.

Kodama and Funazaki [1] investigated the profile loss generation mechanism from a viewpoint of blade drag forces, friction drag force and pressure drag force, and categorized the profile loss components into the loss due to friction drag or the loss due to pressure drag. The profile loss components associated with the effects of base pressure were categorized as the loss due to pressure drag. This paper aims at clarifying the mechanism to determine the base pressure level from a viewpoint of blade drag forces and investigating the influences of the base pressure on the total profile loss. In the study, two kinds of LPT blade design with different levels of base pressure are used. One is the design with the base pressure higher than the mixed-out downstream static pressure and another is the design with the base pressure lower than the mixed-out downstream static pressure. The recommendations for the LPT airfoil design to minimize the profile loss are made based on the findings from the study.

[1]   Kodama, H. and Funazaki, K., 2021 “A Key Flow Parameter to the Profile Loss of Low-Pressure Turbine Blades,” ASME paper GT2021-58887.

Presenting Author: Hidekazu Kodama Iwate University

Presenting Author Biography: Since 2018 Visiting Professor of Iwate University<br/>2013-2017 Fellow, IHI Corporation<br/>2007-2013 Associate Director, IHI Corporation<br/>2004-2007 General Manager of Advanced Technology Department, IHI Corporation<br/>1977 Entered IHI Corporation<br/>Degrees Doctor of Engineering, Kyusyu University, 1999.<br/> Master of Engineering, Kyusyu University, 1977.<br/> B.S. in Aeronautics, Kyusyu University, 1975.

Authors:

Hidekazu Kodama Iwate University
Ken-Ichi Funazaki Iwate University