Influence of roughness on lubrication characteristics of high-speed helical gears in aviation engines

粗糙度对航空发动机高速斜齿轮润滑特性的影响研究

¹ School of Power and Energy, Northwestern Polytechnical University, Xi'an 710129, China
² AECC Hunan Aviation Powerplant Research Institute, Zhuzhou 412002, China

Received: 7 February 2024

Abstract

This study investigates the lubrication characteristics of a certain type of high-speed helical gear in aviation engines. Employing a thermo-elastohydrodynamic lubrication model based on finite line contact, it considers the influence of helical gear surface roughness at the meshing position. Findings reveal patterns in how roughness wavelength, amplitude, and dimensionless parameters (material parameter G, speed parameter U, load parameter W) affect lubrication. By introducing the standard deviation of oil film characteristic parameter fluctuations (pressure, thickness, temperature rise), the extent to which different input parameters impact film stability is quantified. Results show that gear surface roughness significantly destabilizes the lubricant film. With roughness on the same order as the film thickness, fluctuations of oil film parameters can reach 50% relative to the smooth case, significantly reducing local film thickness in the contact region compared to the central area and increasing the risk of dry friction. Increases in roughness amplitude and decreases in wavelength exacerbate fluctuations, while roughness distribution in the gear rolling direction more significantly affects lubricant flow. With rising G, oil film pressure and temperature fluctuations intensify, while increasing U suppresses pressure fluctuations caused by roughness to some extent. Greater W magnifies the impact of roughness. Improving lubrication conditions for helical gears can be achieved by minimizing surface roughness peaks and avoiding dense distributions of sharp roughness spikes.

摘要

针对航空发动机某型高速斜齿轮, 基于有限长线接触热弹流润滑模型, 考虑斜齿轮表面粗糙度的影响对啮合位置开展了润滑特性研究。获得了粗糙度波长、幅值、无量纲参数(材料参数G、速度参数U、载荷参数W)对斜齿轮润滑特性的影响规律。引入油膜特征参数(压力、膜厚、温升)波动标准差, 量化了不同输入参数对润滑油膜稳定性的影响程度。结果表明, 齿轮表面的粗糙度显著影响润滑油膜的稳定性, 当齿面粗糙度与油膜厚度处于同一量级时, 油膜特征参数相较于光滑解的波动幅度达到50%, 导致接触区局部油膜厚度显著低于中心区域, 增加了干摩擦的风险。粗糙度幅值的增加与波长的减少会加剧油膜特征参数的波动, 齿轮卷吸速度方向的粗糙度分布情况对润滑油流动的影响更为显著。随着G的增加, 油膜压力与温升的波动更为剧烈, 而参数U的增加会在一定程度上抑制粗糙度带来的压力波动, W的增加则放大了粗糙度的影响。通过减小齿轮表面粗糙度峰值, 避免粗糙度尖峰的密集分布, 可以有效改善斜齿轮的润滑状态。