Numerical Simulation And Experimental Research On Zhe Jiang Mao-Yangdang Shaft Tubular Pumping Device

With the agricultural and urban drainage standard improving in our country, Some large drainage pumping stations whoes water-head in0～2m or so have been or will be built along the rivers and lakes over the past decade. These pumps’ significant features are large flux and low-water-head which belong to the ultra-low-head pumping stations. It is not available for common type of pumps such as the elbow (or dustpan shape, bell) matched with siphon or straight vertical pump device. Comparatively, shaft tubular pump device is the type of horizontal spindle pumping station and in this way it is beneficial to layout of civil engineering structure, at the same time, it has a straight flow passsage, a good hydraulic performance and a relatively high efficiency of pump device, moreover, the motor and gearbox are put in the open pit with good ventilation and lighting conditions,which is especially suitable for low-head pumping stations.ZheJiang Mao-yangdang shaft tubular pump is a low-water-head unidirectional drainage pumping station with front-positioned pit inlet port and diffusion straight pipe outlet conduit. This pumping station was taken as the research object in this paper, which adopts the method of numerical simlation combined with model text. Details are as follows:(1) Change the shaft passage first、tail lines and select a scheme with better hydraul ic performance from18kinds of optimization schemes. Fouthermore, research its interna-1characteristics and hydraulic loss with and without pump device.(2) By combining the numerical simulation and model test, Observe the transparent organic glass flow pattern and investigate the relationship between hydraulic loss and flux of transparent organic glass.(3) Research on internal and external characteristic of optimization scheme by adopting the method of numerical simulation, internal character including the velocity distribution of pump inlet section, on the other hand, it’s aim at researching the energy curve including flux-water head curve and efficiency curve of external features.(4) Compared with hydraulic loss of outlet conduit under the condition with and without pump. Researching the average velocity circulation of guide vane outlet section impact on passage hydraulic loss.(5) Carried on the numerical simulation for Mao-yangdang. The result reveals that average velocity circulation in different radius of the impeller outlet section; average vorticity along with the changes in flux; average velocity circulation, average vorticity trend along with the changes in flux; average velocity circulation, average vorticity along with the changes in flux of impeller outlet to the export of various guide vane section; average velocity circulation in different radius of the guide vane outlet section and relationship between average velocity circulation and hydraulic loss of the guide vane outlet section.(6) Test the energy curve under different blade angles and compare the results of numerical simulation with model test,after that,contrast the curve of flux-water head between MAO and model pump section.It comes to the following conclusions:(1)The front lines and back lines features of shaft passage are changed with different lines sch emes. Comparison of different schemes’inner flow show thatelliptic equations for front shaft pas sage and inverse arc lines for back shaft passage were much better. Analysis results of optimized schemes’ numerical simulation showed that the streamlines were smooth and the distribution of i nternal flow field of optimized schemes was reasonable, without any obvious instable flow inclu ding vortex, flow separation or bac-k flow.(2) In order to validate the numerical simulation results, the transparent organic glass model of shaft passage was designed and manufactured for testing the hydraulic loss of passage and observing the flow condition. The experimental results showed that the passage’s hydraulic loss was directly proportional to the square of flow, and the numerical calculation consistent with test results.(3) Numerical simulation is carried out on the whole pump device,which consist of optimizational shaft inlet conduit with pump device and outlet passage.It can get energy curve, the numerical simulation results show that the pump assembly efficiency is high, high efficient area is wide.(4) Research on inlet and outlet conduit hydraulic loss under the condition with and without pump. Results show that the rotation of the impeller changes the flow field distribution of inlet conduit and its hydraulic loss is less than without pump’s one. There is a big difference between hydraulic loss of outlet passage with and without pump because of the the guide vane exit residual velocity circulation, outlet conduit hydraulic loss is proportional to the square of the flux. In the opposite, on the condition without pump the hydraulic loss of outlet conduit under design point is samller than deviation point. The shape of the curve is decreases first and then increases.(5) The results of Mao-yangdang numerical simulation show that the average velocity circulation is inversely proportional to the flux under the same radius of impeller outlet section, larger radius larger average velocity circulation under the same flux; the relationship between hydraulic loss of guide vane outlet section and changes in flux is decreases first and then increases, as well as the average average velocity circulation; The distribution of average velocity circulation and average vorticity along with changes in flux are consistent in which impeller outlet to guide vane outlet, it presents that the trend of the curve declines significantly where close to impeller and guide vane, in the opposite, the trend of the curve changes slowly in the middle section. The distribution of average velocity circulation in the different radius guide vane outlet section is smaller radius smaller average velocity circulation, larger radius larger average velocity circulation. Also curve changes obviously under small flux, on the other hand curve changes slowly under large flux.(6) Energy performance test is carried out on the pump device. It is abtained that flux-water head, flux-power, flux-efficiency. Analyzing the results of model test and numerical simulation, the conclusions show that efficiency of model pump devices in the range of low-water-head are higer. Besides, contrast the results of numerical simulation between Mao-yangdang pump section and model pump section, it shows that the curve trend of flux-water head is consistent, water-head deviation is hydraulic loss.