Design And Internal Flow Study Of Rotational-flow Self-priming Pump

With the rapid development of modern industry, increasing demands on fluid machinery has been put forward, which request fluid machinery can operate with high efficiency, low noise, and reliable stability. Pump as a widely used fluid machinery is no exception. In order to greatly improve the pump performance, new design methods are needed to design new pumps, and new approaches should be used to study the flow mechanism of the pump.On the basis of summarizations of the latest foreign and domestic theoretical researches on centrifugal pump and self-priming pump, this paper presents in-depth studies of a new rotational-flow self-priming pump designed with the new method by means of theoretical analysis, steady and unsteady three-dimensional numerical simulation of internal turbulent flow field, and the PIV measurement. Main research contents and innovation achievements were as follows:1,Compared with ordinary centrifugal pumps, diversion wall, forced vortex gas-liquid separator chamber, lug boss and other additional structures are added in the rotational-flow self-priming pump. According to these special structures, the gas-liquid two-phase flow in the process of gas delivery, gas-liquid mixture, the formation of bubble and gas-liquid separation in the starting stage were investigated. Based on Tollmien plane jet theory, gas-liquid two-phase flow equations at the impeller outlet were obtained.2,On the basis of existing design theory of self-priming pump, with the results of this study, the hydraulic design methods of flow passage components of rotational-flow self-priming pump were summarized.3,Commercial software CFX was used to solve the steady liquid three-dimensional incompressible turbulent flow of the rotational-flow self-priming pump, and standardκ-εturbulent model was used in this calculation. RNGκ-εturbulent model and mixture model was applied in the calculation of gas-liquid two-phase incompressible turbulent flow in this pump. The law of internal flow of this pump was investigated through different calculations.4,Large eddy simulation was applied to solve the unsteady three-dimensional incompressible turbulent flow in this pump, and the internal flow field changes with the time was obtained. Complex flow field was observed inside the pump, such as the vortex, shock, attack angle offset, etc. Through the LES calculation of the internal flow filed, more information of the internal flow mechanism can obtained. And by setting a large number of monitoring points, the pulse of the situation inside the pump can be investigated.5,The prediction model was designed, the impact of the structure parameters on the performance of the rotational-flow self-priming pump was obtained. Through comprehensive analysis, the higher and lower impact of lug boss height ht, diameter d,, the height of separation chamber hf, and the corners of the diversion wallθon the pump performance was obtained. The optimal combinations of structure parameters were obtained by studying the relationship between the higher and lower impact of the structure parameters on the pump performance.6,The model pump was designed to satisfy the requirements of PIV measurement, and the special test bench for rotational-flow self-priming pump was designed and built. The internal flow of rotational-flow self-priming pump under different conditions was measured by PIV. The distributions of the relative velocity were obtained by processing the absolute velocity through a special designed program. Compared with the numerical simulation results, the PIV experimental results basically coincided with the results of CFX.In this paper, the distributions of the internal flow field of rotational-flow self-priming pump were studied by means of theoretical analysis, numerical simulation and PIV measurements. Through the Orthogonal Design method, the impact of the structure parameters on the pump performance was investigated, which contributed to the theory of rotational-flow self-priming pumps, and can also provide a reference for further in-depth study of this kind pump. The results presented in this paper can give a basis for the optimal design of rotational-flow self-priming pump, which has a certain practical application value for the industry.