Experiment Study On Dynamic Contact Heat Transfer In Fluid Lubrication Condition

The heat transfer in cylinder is directly related to the fuel economy, power performance and reliability. Since the heat transfer between piston-ring and cylinder-liner is an important part of the in-cylinder heat transfer, it has important meaning for the research on heat transfer law between piston-ring and cylinder-liner. In the research of heat transfer on piston ring-pack with a high piston velocity, if the lubricant film between piston-ring and cylinder-liner is simply regarded as thermal resistance, it would significantly reduce the accuracy. Traditional piston-ring lubrication test-rigs focus on friction and abrasion, and their structures and functions cannot meet the requirement of heat transfer research. A new kind of heat transfer test-rig has been developed. This test-rig has been equipped a rotary flywheel and a slider to simulate the cylinder-liner and piston-ring. The heat transfer law between piston-ring and cylinder-liner also has been investigated。The following works and conclusions have been completed in this thesis:1. Common piston-ring and cylinder-liner test-rigs are generally unable to accurately measure the film thickness during high speed conditions and cannot simulate the high heat flux. A new kind of piston ring and cylinder liner test-rig focused on heat transfer research has been designed and established. This test-rig has been equipped a rotary drive mechanism and a high-power heating source to effectively simulate the high speed working conditions and the in-cylinder thermal state.2. The effects of four factors on the lubricant film thickness and friction were discussed. In addition, through orthogonal test, affecting sensitivity of four factors was also obtained. Affecting sensitivity on lubricant film thickness:slider temperature> speed> inlet lubricant temperature> load; on friction:speed> inlet lubricant temperature> load> slider temperature.3. Discussed the heat transfer conditions between flywheel and slider. The variations of in-slider heat, friction heat, lubricant flow heat and lubricant conduction heat in test conditions were obtained. Besides, compared the lubricant flow heat, lubricant conduction heat and the total heat.4. Mapped the experiment results to actual engine. A conclusion about piston-ring and cylinder-liner heat transfer has been obtained:during the high speed engine condition and hydrodynamic lubrication piston-ring state, if the inlet lubricant temperature and ring-face temperature have a significant difference, the piston-ring lubricant film cannot be simply regarded as thermal resistance, flow heat transfer should be considered too.