The Research On The Internal And External Characteristics Of Centrifugal Pump Based On Sinusoidal Tubercle Volute Tongue

Centrifugal pump as an important fluid transfer machinery,is an important part of social and economic development and national production life.The rotating impeller and the stationary volute inside the centrifugal pump will produce the rotor-stator interaction,which will produce periodic pressure fluctuations.Pressure fluctuations will produce high frequency vibration and noise inside the centrifugal pump,generating a large amount of energy loss,which seriously affects the performance of the pump.The structure of the volute tongue has a great influence on t the rotor-stator interaction in the centrifugal pump,and the reasonable design of the tongue shape can reduce the rotor-stator interaction in the pump and reduce the energy loss in the pump.In this paper,inspired by the raised wavelets on the pectoral fin of humpback whales,we designed a sinusoidal tubercle volute tongue(STVT)with different shapes in the original volute tongue(OVT)and analyzed its pressure pulsation characteristics and energy loss characteristics.The main studies are as follows.(1)Designing the tongue models.Based on the bionic principle,five different shapes of sinusoidal tubercle volute tongues were designed based on the original volute tongue(OVT).According to the size of the sinusoidal structural features,the bionic tongue models were named STVT-1,STVT-2,STVT-3,STVT-4 and STVT-5.(2)A performance comparison between the prototype pump and the bionic pumps was performed.The head coefficient curves and efficiency curves of six model pumps were tested.It was found that the performance of the bionic pumps was better compared with the prototype pump,where the head increase was not significant and the efficiency increase was more obvious.Among all the bionic pumps,STVT-5 has the best performance with 2.4%increase in head coefficient and2.5%increase in efficiency.(3)The internal flow field analysis of the bionic pumps and the prototype pump was performed.The velocity streamline distribution,pressure distribution and turbulent kinetic energy distribution of each model pump were analyzed by combining the results of steady calculation of six model pumps.The results point out that the bionic tongue improves the flow field inside the model pump,resulting in smaller vortex scale inside the flow field,more stable flow,and more uniform pressure while reducing the turbulent pulsation frequency near the tongue,which is a reduction of energy loss inside the pump.Among all the bionic pumps,STVT-5 has the best improvement,with the smallest vortex scale and the lowest energy loss in the flow field,and STVT-4 has the next best effect.(4)The pressure pulsation characteristics of the bionic pumps and the prototype pump were analyzed.Combining the unsteady calculation results of the six model pumps,the pressure pulsation intensity distribution,the pressure pulsation time domain diagram,the frequency domain and the vortex core distribution at the tongue of each model pump were analyzed.It was found that the regions where pressure pulsation occurred were mainly concentrated in the tongue region of the volute and the impeller outlet region;among them,the pressure pulsation near the tongue was the largest,and the pressure pulsation in the downstream region of the tongue was smaller compared to the tongue and the volute runner.Compared with the prototype pump OVT,the pressure fluctuation of the bionic pump is smoother and lower in amplitude.The model pumps with four nodal bionic tongues(STVT-2,STVT-4 and STVT-5)showed a greater reduction in pressure pulsation amplitude than STVT-1 and STVT-3.Among them,STVT-5 was the most effective,with 12.5%(T1),45.2%(T2),69.7%(T3),50.1%(T4)and 51.7%(T5)reduction at the blade passing frequency(BPF),respectively.At the same time,the bionic tongue changes the large vortices near the original tongue into small vortices,and the wide strip vortices into small fine vortices,and the total amount is greatly reduced.The vortex cores of STVT-5 occupy the least area and energy,which reduces the effect of the rotor-stator interaction and reduces the pressure pulsation in the flow field.(5)The energy loss characteristics of the bionic pumps and the prototype pump are performed.The energy dissipation of each model pump was investigated by introducing the total enstrophy and enstrophy transport equation analysis methods in conjunction with the unsteady calculation results of the six model pumps.The total enstrophy curves of the bionic pumps are smaller than those of the prototype pump;STVT-1 and STVT-3 have a small reduction in the average total enstrophy of less than 3%in one cycle;STVT-2,STVT-4 and STVT-5 have a reduction of more than 9%,among which STVT-5 has the largest reduction of 10.01%.Comparing the total enstrophy distribution on different y~+value planes at different moments,it shows that there is a more obvious reduction in the energy loss in the pump for the tongues of the four sinusoidal tubercles,and the high energy loss region of STVT-5 occupies the least area at all moments.