Aerodynamic Aspect of the Problem Relating to the Reduction of the Vibration Strain in the Axial Compressor Blades of the Gas Turbine Engine

Abstract

Consideration was given to the design methods available in practice for an increase in the vibration reliability of the blades of axial compressor. The problem was formulated to show the possibility of the reduction of the strain in the blade nib by the control of the exciting aerodynamic forces. When it is impossible to eliminate the resonance completely and the measures taken to increase structural damping fail to give positive effect it is reasonable to make use of the possibility of the strain reduction by the control of the excitation source. Consideration was given to the aerodynamic aspect of the problem relating to an increase of the vibration reliability of the blades of axial compressor. The aerodynamic loads affecting the axial compressor blades ranging from the trace to potential effects of adjacent shrouds were determined numerically. The program package SUnFlow with the realized in it numerical integration of the Reynolds-averaged Naiver-Stocks equations was used as an investigation tool. The high-pressure compressor stage containing 120 blades of the input guide unit, 83 operating blades and 104 blades of the guide system was used as a test object. The computations were done for the initial structure of the compressor stage and for the stage structure with embedded measures in the form of the variable- pitch input guide unit. Nonstationary computations of the options were done by including the three stage rings into the computation domain of total circumferences. Based on the obtained computation data, the integral and distributed loads onto operating blade were analyzed for comparable stage options. For the obtained distributed loads, the bend strains were calculated using the rod theory. Based on the obtained experimental data, the conclusion was made that the strains can be reduced in the blade nib by the control of the exciting aerodynamic forces.