Fluid-solid Coupling Simulation Of Positive Displacement Motor

Positive displacement motor(PDM) is driven by hydraulic power. Fluid of fixed displacement, which flowing though the sealed chamber, rotates the rotor to provide the power of the system. As the strong output torque and working stability of PDM, it is widely used in geological exploration, oil drilling, construction of pipeline buildings and the defence engineering. The complex work environment of PDM(such as the sudden increase of rock hardness, the underground high temperature, the variable PH of mud),will lead to substantial vibration, thermal deformation, stress uneven of the rubber bushing and the seal leakage, which will reduce efficiency and service life of the PDM. Due to the wide application of PDM, the studying is very necessary.The PDM operation can be seen as rotation and collision in hydraulic drive. Currently,the numerical analysis of PDM focused on the CFD or Solid numerical methods, rarely using the coupling calculation, which haven't realized hydraulic drive Simulation.Analyzed by Elastic mechanics and Fluid mechanics, take the general coupling method to solve the contact seal and the Fluid-solid coupling calculation. According to the PDM linear theory, establish the model of 4-lobe motor and realize hydraulic, successfully simulating the dynamic analysis of 4-lobe motor.Taking account of the hyper-elastic rubber bushing and the friction in rotor, limit the flow and change the parameters of reaction torque and rubber thickness, to get the results of rotor rotation/revolution period, rubber bushing strain/pressure and fluid differential pressure. Analyze the optimum condition of different reaction torque, to get the rule that how the rubber bushing thickness influences the performance of the PDM.To sum up, the paper realized the fluid-solid coupling simulation analysis of the PDM,which can help to shorten the period of experiment and play a guiding role in the design of the PDM.