Hydraulic Optimization And Experiment Measurement On Centrifugal Fire Pumps

As one of the most important components in the firefighting system system,the fire pump plays a vital role in the process of extinguishing the fire.The performance of fire pump determines the degree of damage caused by the fire.Fire pump design requirements are stricter than conventional pumps.The design of the fire pump not only needs to ensure the head under 0Q_d,1.0Q_d and 1.5Q_d,but also takes into account the efficiency under 1.0Q_d,the cavitation performance under the 1.5Q_d and the vibration performance under each flow rate,which brings greater challenges to the design of high-performance fire pumps.In order to provide a reference for the design of fire pumps in China,a centrifugal fire pump with a specific speed of 24.7 is numerically calculated,optimized,and tested.The main work and research results as follows:1.Based on CFD,the numerical simulation and analysis of fire pumps under various flow rate were carried out.The results show that there is a hump on the head curve of fire pump,and the efficiency of fire pump is 37.79%under 1.0Q_d.Under different flow rate,the vector of radial force is distributed likes a hex gear.The phase of the pressure peak at the outlet of the blade pressure surface lags.The NPSHr of the fire pump is 2m,2.10m,2.25m and 2.45m under 1.0Q_d,1.2Q_d,1.4Q_d and 1.5Q_d.2.A fire pump test bench was built to test the performance characteristics of the fire pump.The results show that there is a hump on the head curve of the fire pump.The head of the fire pump is 75.68m and the efficiency is 36.84%under the1.0Q_d.The maximum difference in pressure pulsation at the outlet reaches 5.94%of the head of fire pump under 1.0Q_d.The maximum vibration intensity at the main measuring point is 3.32mm/s.The NPSHr of the fire pump is 1.95m,2.04m,2.16m and 2.38m under 1.0Q_d,1.2Q_d,1.4Q_d and 1.5Q_d.3.The fire pump was optimized and numerically simulated.The results show that the head and efficiency of the optimized model are 74.51m and 41.03%under1.0Q_d.There is no hump on the head curve of optimized model.There are fewer vortex cores in the inlet of the optimized model.The maximum peak of pressure pulsation in the optimized impeller is 40.2%lower than that in the original model.The radial force of the optimized model,under the 1.5Q_d,is reduced by 50.7%compared with that of the original model.The NPSHr of the optimized model is17.5%,14.2%,17.7%and 18.3%lower than that of original model under 1.0Q_d,1.2Q_d,1.4Q_d and 1.5Q_d.4.The optimized model was tested.The results show that the head and the efficiency of fire pump is 74.43m and 40.22%under 1.0Q_d.The efficiency of fire pump is 3.38 percentage points higher than that of original model under 1.0Q_d.The range of pressure pulsation coefficient that on the outlet of fire pump is reduced by by an average of 47.12%under 0Q_d,1.0Q_d and 1.5Q_d after optimization.The maximum vibration intensity of the main measuring point is reduced by 28.9%after optimization.The NPSHr of the fire pump is reduced by 21.5%,17.6%,15.7%and16.8%under 1.0Q_d,1.2Q_d,1.4Q_d and 1.5Q_d.