Experimental and Numerical Study on the Hydraulic Characteristics of an S-Type Bidirectional Shaft Tubular Pump

In order to study the characteristics of a bidirectional shaft tubular pump with S-type symmetric airfoil blades, a prototype model was designed, manufactured, and tested. The energy characteristics, cavitation characteristics, and runaway characteristics of the pump were obtained under forward and reverse operating conditions for five different blade angles. Based on the basic equations of the pump and the inlet and outlet velocity triangles, combined with model tests and numerical simulations, the hydraulic performance of the pump was extensively analyzed and evaluated. In addition, semi-empirical equations for reverse efficiency and runaway characteristics were proposed. The dynamic pressure-drop coefficients were introduced to compare the cavitation performance under different flow rates in forward and reverse operations. The results reveal that the efficiency of the pump in reverse operation is greater than that of forward operation only under a very small flow rate. While the cavitation performance of the bidirectional pump in the two operating modes is almost the same, the runaway speed and backflow rate in forward operation are considerably greater than those of reverse operation. The results provide an important reference for the safe and stable operation of bidirectional shaft tubular pumps