描述:
Ball bearing is widely used as rotor supporting.It is a non/negligible source of vibration in aero/engines.The vibration characteristics of the highspeed ball bearing are studied in this paper.Bearing kinematics theory is applied to discuss the basic characteristics of ball bearings.The vibration factors caused by ball bearings are analyzed,and then the vibration model of ball bearings is set up.The effect of the unbalance,the ball passage vibration,the radial clearance and the surface waviness are considered.It is found that the ball passage vibration is excited by the contact force between the balls and the races.Increasing the numbers of ball can reduce the vibration amplitude.The surface waviness which is caused due to the geometric imperfection of ball bearings is considered as one of the important vibration sources of bearing systems.
描述:
The rotating disk cavity is an important part of the cooling-air system of the aero engine, and it has obviously significance to study the internal flow and heat transfer characteristics of the disc cavity, which will be helpful to improve the efficiency of the aero engine. This paper summarizes the existing research results of domestic and overseas.The present work considers the test methods and calculation methods of the flow and heat transfer characteristics of the rotating disc cavity of the aircraft engine. It points out that, the main factors which affect the heat transfer characteristics are the disc chamber speed, the intake volume, the design of the disc cavity pre-rotation/despin structure, and the type of disc cavity system. The influence of these factors on the characteristics of flow heat transfer is summarized. Based on these factors, the disc cavity structure can be optimized and designed, which provides suggestions for reducing the weight of the turbine, improving the thrust-to-weight ratio of the aero engine, and improving the cooling efficiency.