Determining Method for Spoilers Operating Condition at Low Oil Charging Ratio in Hydrodynamic Retarder

In order to reveal the flow features dominated by gas phase working at low oil charging ratio and reduce idling power loss in hydrodynamic retarder, the periodic flow passage computational model of some type hydrodynamic retarder was built with spoiler which may suppress idling power loss. And the flow filed simulation was conducted to investigate the action process of spoiler inside cascades at low oil charging ratio operating condition, thus the trends of parameters such as braking torque, oil charging ratio and pressure difference of spoiler baffle were analyzed under the operating condition of different input rotating speeds and oil charging ratios. The results show that, braking torque changes significantly around 20% oil charging ratio, it reaches the maximum value before 18% oil charging ratio, while drops at 20% as local minimum value then raises again; at microscopic view the oil and air inside hydrodynamic retarder work as stratified flow below 20% oil charging ratio, however when oil charging ratio surpasses the 20% stratified flow phenomenon gets unintelligible; the spoiler baffle can be pressed into retarder case when its pressure difference value is larger than designed preload spring force. Based on these the determining method is proposed and the theoretical foundation of spoilers inside a hydrodynamic retarder is provided.