Analysis of Influence Factors of Guide Vanes Torque in Variable Geometry Turbine Adjusting Mechanism

Abstract

More and more attention has been paid to research on variable geometry turbine engines with the increasing improvement of performance requirements for military turbines. Due to the fixed working angle of the inlet guide vane, the performance of a conventional fixed geometry turbine is optimal only for turbines near the design point. To match the aircraft’s starting, climbing, cruising, deceleration, landing and other working states, it is necessary to change the turbine speed. This will not only reduce the performance of the turbine but also increase the fuel loss. The variable geometry turbine is a perfect solution to this problem. It is not necessary to change the speed of the turbine, but only the working angle of the inlet rotating guide vane of the turbine. The variable geometry turbine can be matched to each state of the aircraft’s entire voyage. The turbine guide vane can be adjusted by 7° to bring about a 10% change in the flow rate of the entire machine. With constant turbine inlet temperature, the fuel loss can be effectively reduced. The rotating guide vane is impacted by the high-temperature and high-pressure gas and cold air in the inner culvert. Hot and cold air produce two types of aerodynamic torque on the rotating guide vane. There is also a friction torque on the rotating shaft of the guide vane. Therefore, the rotating guide vanes of variable geometry turbines are subjected to three types of torques. The main objective of this paper is to study three factors influencing the guide vane torque in the main flow path. The three influencing factors are the turbulence intensity of the gas, the flow ratio of cold gas to hot gas and the location distribution of the gas film holes on the guide vane. In this paper, CFD temperature-fluid-solid coupling algorithm combined with UDF program is applied to solve the torque of guide vane shaft at three influencing factors. The results show that the three factors, turbulence intensity, flow ratio and air film hole distribution, can have a significant effect on the guide vane torque. This is of great significance for the research and design of variable geometry turbines.

Keywords

• Turbulence intensity
• flow ratio
• air film hole distribution
• temperature-fluid-solid coupling algorithm
• UDF program
• rotating guide vane torque