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Shi W.,Jiangsu University | Xu Y.,Jiangsu University | Zhang Q.,Jiangsu University | Wang G.,Jiangsu Province Special Equipment Safety Supervision Inspection Institute Changzhou Branch | And 2 more authors.
Paiguan Jixie Gongcheng Xuebao/Journal of Drainage and Irrigation Machinery Engineering | Year: 2014

In order to investigate the transient operation characteristics of multi-stage submersible pumps, three-dimensional, unsteady numerical simulations were conducted by using the standard k-ε turbulence model, SIMPLEC algorithm based on the sliding mesh technique in Fluent. The performance of the pump was obtained and compared with the experimental results. Besides, the pressure pulsations at various monitoring points were acquired; subsequently they were analyzed in time and frequency domains, respectively. It was demonstrated that the pressure fluctuation at all the monitoring points changes periodically with time, its number of periods is identical to the number of blades but less affected by the number of guide vane blades, its frequency is close to the blade passing frequency. The frequency of pressure fluctuation within the impeller increases gradually towards the impeller outlet and approaches the maximum value there, while the variation tendency of the frequency is opposite within the guide vane. The mostly dramatic pressure fluctuation occurs at the impeller outlet, the main frequency at various monitoring points is almost equal to the blade passing frequency. The amplitude of pressure pulsation coefficient at the monitoring points in the second stage impeller is higher than the first stage impeller. There still are two peaks in the pressure pulsation profiles in the second stage guide vane, suggesting pressure pulsation is not eliminated completely there. Additionally, the main frequency of pressure pulsation in the first stage guide vane is different from the second stage guide vane.

Zhang Q.,Jiangsu University | Xu Y.,Jiangsu University | Ma D.,Fujian Academy of Mechanical science | Zheng W.,Fujian Academy of Mechanical science | And 2 more authors.
Paiguan Jixie Gongcheng Xuebao/Journal of Drainage and Irrigation Machinery Engineering | Year: 2014

Stainless steel casting multistage deep-well pumps have been extensively used in some specific applications where excellent corrosion- and wear-resistance as well as long life-span are highly desirable. Because of stainless steel investment casting multistage deep-well pumps with high cost, they are targeted to mid- or high-end users. By utilizing existing stainless steel casting techniques, a type 150QJS20 multistage deep-well pump was developed. Four kinds of techniques used in the development process are as follows: (1) the guide vane was cast by using outward rather than inward flanging technique to overcome the difficulty in cleaning sand from castings; (2) the inflow diffuser was adopted in this design to reduce manufacturing cost and shorten the axial length of diffuser, and eventually to improve the pump operation reliability; (3) tie-bolts are used to assemble the pump, and connection between stages is realized by spigots filled with O-shape seals, causing a more compact pump construction, convenient transportation and easy maintenance; (4) major accessories are interchangeable in the same series to reduce manufacturing cost. A prototype pump was built and its performance was measured, showing its efficiency being comparable with the international standard level and a greatly improved stage head. Compared with the traditional multistage deep-well pumps, the new type pump has a more compact configuration and lighter weight. Therefore the success in development of 150QJS20 pump can provide useful experience for development of other similar stainless steel casting pumps for mid- and high-end users.

Zhang Q.,Jiangsu University | Shi W.,Jiangsu University | Xu Y.,Jiangsu University | Gao X.,Jiangsu University | And 3 more authors.
International Journal of Rotating Machinery | Year: 2013

For widely used multistage centrifugal pumps, their former structures are so bulky that nowadays growing interest has been shifted to the development of more compact structures. Following this trend, a compact pump structure is provided and analysed. To maintain the pump's pressure recovery, as well as to meet the water flow from the impeller, a circumferential twisted return guide vane (RGV) is proposed. To validate this design method, the instantaneous CFD simulations are performed to investigate the rotor-stator interventions. Within the impeller, the pressure fluctuation is cyclic symmetry, where the impeller frequency dominates. At the zone where flow leaves impeller for RGV, the pressure fluctuation is nonperiodic, the impeller frequency is major, and the rotation frequency is secondary. Within RGV, the periodic symmetric fluctuation is recovered, where the rotation frequency is governing. The fluctuation decreases from seven cycles within impeller to two cycles within RGV, indicating that the flow from impeller is well handled by RGV. To examine the pump's performance, a prototype multistage pump is designed. The testing shows that the pump efficiency is 57.5%, and the stage head is 9 m, which is comparable to former multistage centrifugal pumps. And this design is more advantageous in developing compact multistage centrifugal pumps. © 2013 Qihua Zhang et al.

Zhang Q.,Jiangsu University | Xu Y.,Jiangsu University | Shi W.,Jiangsu University | Gao X.,Jiangsu University | And 2 more authors.
Nongye Gongcheng Xuebao/Transactions of the Chinese Society of Agricultural Engineering | Year: 2013

To design compact multistage centrifugal pumps, a circumferential crankle guide vane was proposed to match their compact structure. The basic design principle originated from the twisted centrifugal impeller design method and the design method of this guide vane was investigated systematically. By fixing the top curve of the guide vane and extending the bottom curve forward along a circumferential direction, a crankle surface is shaped. This design method has two merits. Firstly, the bottom curve of the first guide vane is extended circumferentially forward to guarantee a large throat flow area. And secondly, a diffuser-like passage is naturally formed by the extended surface and the cylindrical surface of the next blade, which enhances its pressure recovery ability. In addition, the blade surface is divided into two segmented parts, that is, a full twisted surface and a cylindrical surface, thus the casting and molding of the guide vane is more convenient. To reduce the design cycle of the guide vane, a hydraulic design system of the circumferential crankle guide vane was developed using the secondary development technique. Based on this system, different configurations of guide vane were developed. Through evaluation of the different configurations of guide vane, an optimal configuration was obtained by means of CFD analysis. To validate the CFD results, a prototype multistage pump was developed and manufactured. The prototype pump testing showed that the stage head was 9 m, and its efficiency was 57.8%, which could meet the design requirement. To conclude, the guide vane design method is beneficial for energy-saving in multistage centrifugal pumps, and this method could provide useful guidance for the development of compact multistage centrifugal pumps.

Ma D.,Fujian Academy of Mechanical science
Paiguan Jixie Gongcheng Xuebao/Journal of Drainage and Irrigation Machinery Engineering | Year: 2011

Based on CFD software Fluent, the flow field of a self-priming centrifugal pump with deflector and jet nozzle was simulated numerically. The internal flow field variables such as velocity vector, static and total pressures were analyzed, and the pump efficiency was predicted. The numerical simulation showed that the velocity vector distribution in the pump is smooth, the static pressure distribution at the two outlets of the new type deflector is uniform and the pressure in each channel is close to an axisymmetric distribution. At the design point the pump head and efficiency predicted are higher than observations by 6.9% and 0.5%, respectively. The performance curve predicted is quite similar to that measured. The experimental results showed that the performance curve of the pump is flat and the pump has an expanded high efficiency zone. The entire technical specifications of the pump have met the design requirements; also the efficiency is better by 16.34% than the imported pumps with the same specifications. To reduce weight and cost the pump casing is made of die-casting aluminium alloy, causing the pump is featured with reasonable design, novel structure, small size, light weight, reliable operation and easy for use.

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