| The high-speed semi-open impeller centrifugal pump is used to increase the pressure of fluid in aerospace industry. It is a important part of the fueling system of the plane and provide the fueling system with the fuel th at has enough pressure. While it appears in the aircraft climbing test that the outlet pressure of pump decreased with the increase of the height which the plane reached. This kind of phenomenon may have bad influences on the operation of plane, so it is n ecessary to do researches to the problem.Theoretical analysis and numerical simulation is used in this article and the main content is as follows:1. The outlet pressure decreasing problem of the domestic single-stage single suction high-speed semi-open impeller centrifugal pump in the experiment was an alyzed and the main reason that lead to the decrease of pressure is obtained — cavitation; In order to improve the cavitation pe rformance of the aerial fuel pump, a method was proposed by adding an inducer in the front of main impeller and the main geometrical parameters of the inducer was calculated; Then the outlet pitch and blade number of inducer was taken to make the simulation pr ojects respectively.2. Three models and schemes of the inducer was made by changing the outlet pitch of the inducer. The inlet pitch of them was 5mm, and outlet pitch was 5mm, 8mm, 11 mm, respectively. For the three schemes, numerical simulation of cavitation flow was carried out by using CFD software Pumplinx, the pump cavitatio n performance was predicted and the distribution law of gas liquid two phase flow in the i nducer and the impeller were studied, under the condition of different net positive su ction head of centrifugal pump, the distribution of pressure and bubble in the i nducer and impeller were obtained. through analysis found that, in a certain range, keeping the import pitch constant, increasing the outlet pitch can make the pump to obtain higher lift and less bubble distribution, meanwhile the cavitation point was mini mum at the same flow rate. Through numerical analysis, for this pump studied in this paper, when the import pitch was 5mm and the outlet pitch was 11 mm can increase the a nti-cavitation performance of the pump the most.3. The cavitation flow numerical calculation of the semi-open impeller centrifu-gal pump was carried out at the different blades number of induction based on inducer inlet pitch at 5mm and outlet pitch at 11 mm. By keeping the pump inlet flow invariant, gradually reducing the net positive suction head to get the cavitation fracture curve of the semi-open impeller centrifugal pump at the blades number was 2, 3 and 4. With the net positive suction head constantly induced, the evolution process of cavitation in the induction was analyzed, the occurrence and development of bubbles was revealed, then the characteristics of pressure distribution in impeller was obtained. Through analysis the results, the influence of blade number on cavitation performance of high speed centrifugal pump was obtained: The development process of cavitation in the inducer with different blade numbers is basically same. The bubble firstly appeared in the blade inlet suction side, with the decreasing of the net positive suction head, the bubble spread on the suction surface and gradually developed to the pressure surface. Compared to the 2 and 4 blades of inducer, adding 3 blades inducer at the centrifugal pump had a high head at the same inlet pressure conditions, and the bubble distribution in flow field was least, cavitation breaking point is lower in the same flow co nditions. The blade number of inducer has a certain effect on the pump cavitation performance, the 3 blade induction round bubble growth rate is slow, and the cavitation performance of centrifugal pump is optimal. Therefore, 3 blades induction was recommended for the semi-open impeller centrifugal pump. |
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