Experimental Study on External Characteristics of Ultra-low Lift and Large-flow Shaft Tubular Pump

Abstract

【Background】 Shaft tubular pump is a new pumping device with its generator installed in an open shaft, which is moisture-proof and has good ventilation. It has several advantages including easy operation and maintenance, low cost, and simple structure. It is generally used in low-lift and large-flow pumping stations. The development in shaft tubular pump has made it a favorable choice for ultra-low lift and large-flow pumping stations like Shenjiang Pumping Station for regional flood and drainage control. 【Objective】 The purpose of this paper is to test in situ hydraulic performance of shaft tubular pump in ultra-low lift and large-flow pumping station. 【Method】 We took Shenjiang Pumping Station as an example; the external characteristics of its shaft tubular pump were studied using the method of model test, from which we propose plans to improve it. 【Result】 When the blade angle was 0°, the pump was most efficient, reaching 77.57%, with the flow rate and lift being 220.5 L/s and 1.95 m respectively. In the range of the lifts we tested, the pumping station had sufficient cavitation margin and did not cause cavitation damage. When the blade angle was 0° and maximum lift was 2.93 m, the runaway speed was 1.80 times the rated speed. The flow in the original design was too slow while its associated runaway speed under maximum lift was too large, not ideal for safe operation of the pumping station. An optimization scheme for increasing the rated speed of the pump was proposed. Verification against experimental data showed that the energy and cavitation characteristics, runaway speed all met the requirements. 【Conclusion】 The shaft tubular pump has a good hydraulic performance and efficiency, and it is potential for use in ultra-low lift pump stations.

Keywords

• pump unit
• model test
• shaft tubular pump
• external characteristics
• extra-low head and large flow pumping station