Experimental study of shear-driven film flows in aeroengine bearing chamber

Abstract In the thermal analysis of the aeroengine bearing chamber, it is necessary to study the flow characteristics of the oil film and grasp the change law of the flow state based on the thickness of the oil film. Therefore, based on the motion analysis of the oil film on the inner wall of the bearing chamber, an experimental study was carried out to analyze the thickness of the shear-driven liquid film. The experiment was carried out in a rectangular channel, and the moving oil film was driven by the shear of the air flow generated in the channel by stabilizing the air source and the oil film generating device. In the experiment, a high-speed camera and a laser displacement sensor were used to obtain images of the flow of the liquid film on the metal plate and the instantaneous film thickness. The experimental conditions refer to the high-speed bearing cavity test bench, the maximum air flow Reynolds number reaches ( Re a ) 51,000, and the liquid film Reynolds number ( Re f ) ranges from 430 to 2149. By observing the influence of air flow on the fluctuating structure of the liquid film surface, the flow state of the liquid film was qualitatively analyzed. Based on the experimental data and the existing liquid film flow model, the liquid film thickness was predicted by combining the interfacial shear factor. In this paper, the dimensionless analysis method is used to compare the prediction results with the previous flow model, and the results show good agreement. The instantaneous thickness signal was processed by statistical methods, and the surface fluctuation characteristics of the liquid film were analyzed and compared, including the degree of surface fluctuation and spectral analysis. In addition, the surface fluctuation structure of the liquid film is discussed, including the relationship between the bottom liquid film, the average thickness value and the maximum value. The results show that the ratio of the maximum thickness of the liquid film to the average film thickness can reach 4.5. This means that under certain operating conditions, the average liquid film thickness does not reflect the flow state of the liquid film well. When analyzing the heat transfer relationship between the oil film and the wall surface, it is necessary to select the appropriate liquid film thickness parameters to study.