Scale-resolving Simulation And Experimental Verification Of Different Working Media Flow Based On Stator/Rotor

In recent years,typical stator/rotor mechanical structure has been applied in many aspects of our life,such as marine propeller,fan,retarder,hard disk etc.So the study of different working media flow around stator/rotor blades has great practical significance.Many stator/rotor machinery work in the liquid,such as marine propeller,retarder and mixer etc.Marine propeller is widely used now,which has played a crucial role in the shipbuilding industry since its invention.Hydraulic coupling has many applications in the fields of automobile,mining industry,electric power,construction machinery and so on.It is important to improve the transmission quality of the working machine,reduce the energy loss in the transmission process and increase the huge economic benefits.In this paper,The hydraulic coupling and the propellers were selected as the research objects,respectively.Then,a series of problems caused by the complex turbulent flow around the stator/rotor blades was studied.In order to accurately calculate the flow around the stator/rotor blades and the external mechanical characteristics,Scale-Resolving Simulations were employed to conduct the numerical simulation.Then,the PIV test system of miniature propeller was designed.It was concluded that the method could capture the details of the flow field and proved that the method was suitable for the flow around the stator/rotor blades by comparing the PIV test and simulation results.The major research works and related conclusions are showed as follows.1.Scale-Resolving Simulation for flows of stator/rotor working in oil mediumIn order to simulate the complicated transient flow field inside the fluid coupling under braking condition,the LES method in the advanced Scale-Resolving Simulation methods was introduced.According to the working principle and characteristics of the fluid coupling,the LES model of the transient flow of the fluid coupling field was established to evaluate the ability of six sub-grid models by predicting the internal flow field and performance of the coupling.In the prediction of braking torque,DSL and KET showed the smallest errors(less than 5%)at low speed,while the errors of other models were more than 5.6%.With the increasing of the rotational speed,the prediction errors of all the subgrid-scale models gradually maintained at 4%,except SL.The results showed that DSL and KET captured abundant vortex structures and provided a relatively moderate eddy viscosity within turbine.In the pump,all the subgrid-scale models gave rich vortexes and were hardly told the differences through qualitative analysis.In general,DSL and KET were applicable to obtain the more accurate results and depict the flow field.2.RANS simulation for flows of stator/rotor working in water mediumIn order to solve the problem of predicting the characteristics of propeller,the multi-flow coupled field was employed based on the working principle and characteristics of the propeller.Eventually,a wide computational domain with k-? turbulence model was proposed.Compared with the simulation results in the previous literature,the parameters were in good agreement with the experimental values.3.Scale-Resolving Simulation for flows of stator/rotor working in water mediumIn order to predict the transient flow field of a propeller and reduce the computational workload,a periodic passage model of propeller with Scale-Resolving Simulations was established.Although the results of the SRS methods were a bit larger than that of steady simulation,the calculated values agreed well with the experimental values and met the engineering requirements.The vortex structures of the transient flow field were analyzed and it was found that SBES provided a swifter development of three-dimensional turbulence than DDES and more ordered turbulence structures than DLES.Meanwhile,it was verified that the ability of the SBES models to generate unsteady structures in the mixing layer depended on the grid provided in that area.4.Scale-Resolving Simulation for flows of the scaled-down propeller and itsexperimental validationIn order to measure the complex flow field around the stator/rotor blades,the numerical simulation of the scaled-down propeller was conducted.The PIV test system for the flow field of the miniature propeller was built to compare the results of experiment and the simulation afterwards.It was found that the experimental results satisfied the basic flow field character.By analyzing the simulation and the experiment results contrastively,it was found that the distributions of velocity and vortex of SBES were in good agreement with the experimental data.DLES had a large number of vortex structures,but the vortex structures were overmuch and not consistent with that of the experiment.The characteristics of the flow field distribution of DDES were inconsistent with the experiment and the development of vortex structure was not sufficient.