A water pump design method based on the area ratio principle is proposed. That is, under the condition of keeping the area ratio constant unchanged, matching different impellers on the same deflector to obtain the efficient pump with different parameters. Submersible pump is the most widely used general machinery, not only for industrial use, but also for the vast rural areas. With the development of rural electrification, from domestic water to farmland irrigation, submersible pumps have become indispensable tools. It is widely used, in order to expand the scope of use, this paper presents a method based on the principle of area ratio pump design. Submersible pump performance is mainly determined by both impeller and deflector, high efficiency pump not only requires efficient impeller, but also with the impeller well-matched deflector, if the deflector does not fit, not only reduce the pump Efficiency, but also to a certain extent, affect the stability of pump performance. HHAnderson proposed the centrifugal pump area ratio principle, pointed out that the impeller outlet flow area and the throat area ratio is the pump head, flow, shaft power and other parameters of the main determinants. For the first time, RC Worster proved mathematically that the principle of area ratio proposed by HHAnderson was scientific. In our country, the area ratio principle has been introduced since the early 1980s. Some people used the area ratio principle to analyze the existing pumps, but the research work is still not deep enough. Therefore, this paper presents a design method based on the area ratio principle Under the condition of keeping the area ratio constant unchanged, different impellers are selected for the same deflector to obtain efficient pumps with different parameters. The method is validated through experimental research and numerical simulation. 1, the theory of area ratio principle In the design of the pump impeller, the impeller inlet is generally assumed no pre-rotation, vu, 1 = 0, then the basic equation of the pump: Equation 1 Where HT --- pump theoretical lift, m u2 --- Impeller exit circumferential velocity, m / s vu, 2 --- Impeller exit flow absolute velocity of the circumferential component, m / s According to the impeller exit velocity triangle can be seen: Equation 2,3 Assuming the impeller exit to the throat of the flow deflector There is no hydraulic loss in this transition zone, then v2 = vt, substituting (2) into (3) yields: Equation 4 The impeller transfers energy to the liquid, which collects the liquid flowing out of the impeller and draws the liquid out. The deflector does not add any energy to the liquid but affects the pump operating point and maximum efficiency point. The coupling of the impeller and the deflector should follow the continuity equation of the liquid flow: Eq. 5 where vt is the flow velocity at the throat of the deflector, m / s Fth is the throat area of ​​the deflector, in mm2 ω2 --- the relative speed between the impeller exit blades, m / s F2 --- the area between the impeller exit blades, mm2 The equation (5) rewritten as: Equation 6 where Y --- area ratio coefficient The formula (4) , (6) into equation (1), the relationship between the theoretical lift and the area ratio of the pump is: Equation 7 shows that in order to obtain a higher lift of the pump, the area ratio coefficient Y≤1 should be used. Zhang Junda on the 166 kinds of pump hydraulic model area ratio coefficient statistics and regression, and plotted the area ratio coefficient and pump specific rotation curve, obtained most of the pump area ratio coefficient Y ≤ 1, further evidence of The above conclusion is correct. Guo Zijie derived the approximate expression of the area ratio coefficient and the specific rotation number, and counted the area ratio coefficients of a large number of centrifugal pumps, and the data showed that their area ratio coefficients Y≤1. Accordingly, this paper proposes to obtain an efficient water pump through the matching impeller on the same deflector under the condition of keeping the area ratio constant unchanged. 2, the test device and experimental research In order to study the area ratio factor on the performance of submersible pumps, wells with submersible pumps to do the test. On the same deflector were optional 2 kinds of impeller, open test bench in Lanzhou University of Science and Technology test, the same motor test only change the pump. In order to ensure that cavitation and swirl do not occur in the suction zone, the impeller has a sufficient submergence depth under water. The input power of the motor is measured by electric method, and the motor efficiency is estimated according to the efficiency on the nameplate. Take 250QJ125 submersible pump test, while maintaining the area of ​​the throat and the impeller vane blade outlet area ratio of the area ratio factor Y = 0.87 constant under the premise of redesign of an impeller Ⅱ, the impeller installed in the Submersible pump pilot on the test. Optional 2 different impeller submersible pump, their best operating point of the measured data shown in Table 1. Table 1 best operating conditions measured values ​​Table 1 best operating conditions measured values ​​Figure 1 impeller exit vane area schematic 2 throat area of ​​the pilot schematic 1 impeller exit vane the area between the schematic diagram 2 impeller outlet vane area and guide Flow meter throat Table 2 Impeller exit vane area and flow director throat Table 2 Impeller
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