篦齿封严风阻温升特性研究

篦齿封严风阻温升效应引起的热负荷对航空发动机涡轮叶片冷气系统有着重要的影响。采用理论分析、数值计算与实验相结合的方法系统地研究了篦齿封严的风阻温升特性。首先，对篦齿封严风阻温升特性进行了理论分析，设计搭建了篦齿封严风阻温升特性实验台，建立了基于RNG（Re-Normalization Group） k-ε湍流方程的篦齿封严风阻温升数值求解模型。然后，研究了篦齿封严流场特性、泄漏特性和风阻温升特性，并将理论计算、数值仿真与实验测试结果相互对比分析，研究了压比、转速等因素对篦齿封严风阻温升特性的影响规律，揭示了篦齿封严的风阻温升效应产生的机理。结果表明：高低齿篦齿封严结构减弱了篦齿封严的透气效应，增强了篦齿封严的动能耗散，有利于降低篦齿封严的泄漏量；在所研究的工况下，转速低于2 000 r/min时，风阻温升效应较小，转速在2 000~6 000 r/min时，风阻温升随转速的升高而增大，温升值最高可达12.87 K；压比的增大会加强气流的对流换热，转速为6 000 r/min时，压比从1.1增加到1.3，温升值下降了7 K左右；风阻温升产生的主要原因是流经封严间隙的黏性气流与高速旋转的转子相互摩擦产生热量，气流吸收这部分摩擦热导致温度升高，转子转速越高，风阻温升效应越强。所研究的篦齿封严风阻温升特性为航空发动机内通道气流热负荷分析提供了理论依据。

Investigation on windage heating characteristics of labyrinth seals

The heat load caused by windage heating of labyrinth seals plays an important role in the cooling system for the blade of aero-engine turbines. In this paper, windage heating characteristics of labyrinth seals are systematically studied using theoretical analysis, numerical calculation and experimental research. The formula for theoretical calculation of windage heating is analyzed and the experiment bench of windage heating characteristics is designed and built. Based on labyrinth seals, a model for numerical solution of RNG(Re-Normalization Group) k-ε turbulent equation on windage heating is established. The effects of pressure ratio and rotational speed on the characteristics of windage heating are investigated. The results of the theoretical calculation, numerical simulation and experimental test are compared to analyze the flow field characteristics, leakage characteristics, and windage heating characteristics, revealing the mechanism of windage heating characteristics of labyrinth seals. The results show that the structure of high and low teeth weakens the air permeability of the labyrinth seal, enhances the dissipation of kinetic energy, and helps reduce the leakage of labyrinth seals. Under the study conditions of this article, the total temperature rise is relatively small when the rotation speed is lower than 2 000 r/min, the total temperature of airflow increases as the rotation speed increases to 2 000 r/min to 6 000 r/min, where the air temperature could maximally rise by approximately 12.87 K. The increase of pressure ratio enhances the convection heat transfer of airflow, and the temperature rise drops by 7 K as the pressure ratio increases from 1.1 to 1.3 with the rotation speed of 6 000 r/min. The main reason for windage heating is that the airflow absorbs the frictional heat generated by the abrasion between the viscous airflow through the sealing gap and the high-speed rotating rotor, and the faster the rotor rotates, the higher the temperature rises. The investigation on windage heating characteristics of labyrinth seals in this paper provides a theoretical basis for the heat load analysis of the airflow in aero-engines.