Hydraulic performance of the bidirectional submersible tubular pump with adjustable guide vanes

Abstract: Pumping stations have been highly required for the bidirectional pumping functions to meet the needs of urban flood control and water diversion. Particularly, droughts and floods alternate frequently in some cities along rivers and lakes in recent years. Since the two-way tubular pump device can obtain high efficiency in the forward operation, the performance can deteriorate seriously in the reverse operation. This study aims to improve the hydraulic efficiency of the bidirectional submersible tubular pump in the forward and reverse operation. The adjustable guide vanes were proposed to arrange before and after the impeller. Two flat plates were composed of the adjustable guide vane, where the angle of the guide vane was timely adjusted, according to the running direction. The influence of the front guide vane on the flow state of the influent was reduced to improve the circulation recovery capacity of the rear guide vane. A model pump device was fabricated to clarify the effects of adjustable guide vane angle and bulb position on the hydraulic performance of the device. The model test results show that the bidirectional submersible tubular pump with the adjustable guide vanes for both forward and reverse performance, the optimal guide vane angles for the bulb front- and rear-mounted were 12° and 20°, respectively, indicating the highest efficiencies of 67.9% and 66.5%, respectively. The highest efficiencies point flow were about 0.285 and 0.265 m3/s, respectively, where the device efficiency was higher when the bulb was in the front. The efficiency of the bulb front- and rear-mounted type increased by about 7 percentage points and 6 percentage points, respectively, indicating the increase in the efficiency of the bulb type by adjusting the guide vane. In terms of impeller performance, the impeller head and efficiency of the rear-mounted type were higher than those of the bulb front-mounted type. There were small differences between the impeller head and efficiency near the highest efficiency point between the bulb front- and rear-mounted, where the difference in the device performance was mainly caused by the loss of overcurrent components. The minimum loss of the bulb front-mounted type was smaller than that of the rear-mounted type, indicating that the maximum efficiency was greater than that of the bulb rear-mounted type. The loss of the bulb front-mounted type was smaller than that of the rear-bulb type when the flow was large. It was greater than that of the rear-bulb type, when the flow was small so that the high-efficiency area of the front-bulb type was shifted to the large flow. The hydraulic loss of the bulb front-mounted type was concentrated in the rear guide vane and the water outlet channel, whereas, the hydraulic loss of the bulb-front type was mainly concentrated in the rear guide vane, the bulb section, and the outlet channel. There was small hydraulic loss of the bulb section on the water inlet side. But the reduced hydraulic loss on the water outlet side was caused by the water outlet channel when the bulb was reduced rearward. Compared with the conventional guide vanes used in the current bidirectional tubular pump device, the adjustable guide vanes can widely be expected to significantly improve the hydraulic efficiency during reverse operation, indicating a great engineering significance for the construction of the bidirectional pump station.