密封气流流量对轴承腔外壁滑油运动的影响

Influence of Sealing Air Mass Flow Rate on Bearing Chamber Outer Wall Oil Movement

为了研究密封气流质量流量对轴承腔外壁面上滑油分布及温度分布的影响,基于拉格朗日离散相模型(DPM)和液膜模型,利用STAR CCM+商业软件对轴承腔内油滴运动、油滴向油膜的转化以及油膜在轴承腔内的运动开展非稳态数值模拟计算,并与德国Karlsruhe大学轴承腔油膜厚度试验结果进行对比。结果表明:计算值与试验值在高转速下一致性较好,平均相对误差13.6%;低转速下由于空气分布均匀性较差,个别工况点计算值与试验值存在一定误差,但最小相对误差在4%,总体上具有较好一致性;随着轴承腔密封气流的质量流量的增加,轴承腔内空气的平均流动速度提高,对轴承腔外壁面上油膜的剪切作用和扰动能力增强,导致轴承腔的外壁面油膜厚度和稳定性降低;轴承腔外壁面上的温度分布与油膜的厚度分布一致,最小温度分布在壁面上被油滴冲击位置;随着轴承腔密封气流的质量流量的增加,轴承腔外壁面上低温分布范围增大,但温度分布均匀性变差。

In order to study the influence of seal gas mass flow rate on the oil distribution and temperature distribution on the outer wall of bearing chamber,based on the Lagrangian Discrete Phase Model(DPM)and the liquid film model,the unsteady numerical simulation of the movement of oil droplets in bearing chamber,the transformation of oil droplets to oil film and the movement of the oil film in bearing chamber were carried out using STAR CCM+commercial software,and the results were compared with the test results of the thickness of oil film in bearing chamber at Karlsruhe University in Germany.The results show that the calculated values are in good agreement with the test values at high rotational speed,and the average relative error is 13.6%.At low rotational speed,due to poor air distribution uniformity,there is a certain error between calculated values and test values at individual operating points,but the minimum relative error is 4%,which is generally consistent.With the increase of the mass flow rate of the seal gas in the bearing chamber,the average flow velocity of the air in the bearing chamber increases,and the ability to shear and disturb the oil film on the outer wall of the bearing chamber increases,resulting in the decrease of the thickness and stability of the oil film on the outer wall of the bearing chamber.The temperature distribution on the outer wall of the bearing chamber is consistent with the thickness distribution of the oil film,and the minimum temperature is located at the position where the oil drops impact the wall.With the increase of the mass flow rate of the seal gas in the bearing chamber,the low temperature region on the outer wall of the bearing chamber increases,but the uniformity of temperature distribution becomes worse.