CFD Research-based Heavy Vehicle Retarder Structure Parameter Optimization

Heavy vehicle has been one of the most important transportation tools in our country, but it is very heavy、 has a big inertia and long braking length, it also often works on bad road conditions, so it is very hard to ensure vehicle’s safety and comfort performance when only using single service brake system. Research shows that heavy vehicles often combine the service brake system and the hydraulic auxiliary brake system together to ensure the braking performance, and it is also an important research field in the development of braking system. But hydraulic retarder’s development in our country is slower than developed countries, the design theory of which is far from mature and deep, this paper uses beam theory、 similarity theory and computational fluid dynamics methods to simulate the pressure fied、 relative velocity field and analysis braking performance of the hydraulic retarder.Study on the flow control equations in rotational coordinate and numerical simulation method in three-dimensional flow. use the Cartridge filtering model in LES and smargorinsky model to simulate the flow field inside the hydraulic retader; Research on the calculation method of coupled multi flow area, and choose the sliding mesh method to simulate the flow in the interface area.Use the similarity theory, the beam theory to analysis the internal flow field of circulating flow and braking torque, and build the theory model of the hydraulic retarder’s braking torque, then make sensitivity analysis of braking torque when blade angle varies.Simulate the inner flow field of hydraulic retarder under fully filled condition using LES model, analysis the transient changes in the interface of static pressure, velocity distribution, and simulate the inner flow field characteristics on different rotor speeds, analysis the static pressure distribution and velocity distribution on blade’s surface, predict the braking performance and validate it by experimental results.Analysis the flow field distribution and the braking performance which is calculated by using the CFD method, when a structural parameter varies. Set up a series of models about each structure parameters, analysis the flow pattern, pressure distribution and the braking performance, according to above results, get the relatively optimum model in the model list.