Numerical Simulation and Experimental Study of Heat Accumulation in Cylinder Parts During Internal Rotating Plasma Spraying

Abstract

Internal rotating plasma spraying has been widely used in industrial applications to enhance performance properties and prolong the service life of internal components, such as gas turbines, engine blocks, and oil pipelines. As it is difficult to dissipate the excess heat in the limited and semi-enclosed space, the temperature characteristics of the internal parts have a significant influence on the spraying process. In this study, a three-dimensional (3D) numerical model was developed to describe the temperature evolution and distribution of a cylinder under different heating modes that considers one (plasma jet only) and two contributions (plasma jet and sprayed particles), respectively. Moreover, air and water cooling modes were also implemented to alleviate the heat accumulation of the cylinder. The results indicated that heat accumulation was mainly caused by plasma jets, whereas the sprayed drops contributed slightly. The temperature increased abruptly from initial 283 to 550 K after two back and forth movements within the cylinder without the application of coolants. However, the temperature could be controlled at 420 K under the condition of air cooling and at 390 K under the condition of water cooling. Using an infrared camera and temperature sensor, experiments were conducted to validate the numerical model corresponding to the working conditions implemented in the numerical simulation. A decrease in the porosity and increase in micro-hardness of the coating could be achieved under the cooling effect of water, rather than the compressed air. The percentage improvements in the porosity and micro-hardness of the coating were approximately 14.2 and 6.1%, respectively, by the application of water cooling.