双吸离心泵叶片交错角度对压力脉动影响研究

发布时间：2018-04-04 22:21

本文选题：双吸离心泵　切入点：压力脉动　出处：《中国农业大学》2017年博士论文

【摘要】：双吸离心泵在水利、农业和能源和化工等领域广泛应用。双吸离心泵压力脉动与振动、噪声、汽蚀等密切相关,是其典型非稳态运行特性之一。本文通过设计、制造5种不同叶片交错角度的双吸离心泵,并进行系统的实验研究与CFD计算,系统揭示了叶片交错角度对双吸离心泵压力脉动和水力特性的影响。建立了一套典型双吸离心泵试验装置,针对5种不同方案下的叶片交错角度(0°、12°、24°、36°和48°)在不同流量工况下进行了压力脉动特性试验验究,得到了各测点压力脉动与叶片交错角度的关系。结果表明:(1)叶片交错角度对双吸离心泵的扬程和效率无显著影响。(2)吸水室压力脉动在空间上分布较为均匀,最大脉动出现在隔板位置。吸水室压力脉动受叶轮旋转作用的影响较大,在频率上表现为叶轮转频的谐次频和1/2倍的叶片通过频率。叶片交错角度对吸水室压力脉动幅值影响较小。(3)叶片交错角度对压水室压力脉动影响较大,尤其是对叶频幅值影响显著。比较不同方案的试验结果,当叶片交错角度接近均匀交错(360°/2*N)时,压水室的压力脉动分布较为均匀,压力脉动值最低,比非交错叶轮可降低50%以上。(4)建立了流量与压力脉动的关系。在正常操作范围(0.6Qn～1.2Qn)内,压力脉动较小,在小流量区压力脉动增大,其中吸水室在0.2Qn和1.2Qn工况下,其1/2倍叶频压力脉动系数最大分别是额定工况下幅值的3.86倍和1.11倍;在压水室内,压力脉动主频为叶频,在0.2Qn和1.2Qn工况下,其主频最大压力脉动系数分别是额定工况下幅值的0.98倍和2.01倍。开展了双吸离心泵在不同叶片交错角度的压力脉动特性的数值研究,所得到的双吸离心泵能量特性和压力脉动模拟结果与试验结果基本一致。通过分析泵流场的时域图、频域图、压力场分布和涡结构等随叶片交错角度改变而演变的过程发现,压水室和叶轮流场中游移涡强度随叶片角度由非交错向均匀交错方案靠近而逐渐减弱,叶轮出口的射流-尾迹所形成的二次流也不断减弱,这是造成双吸离心泵压力脉动随着叶片交错角度变化而改变的主要原因。开展了流量与双吸离心泵压力脉动的关系的数值研究,通过分析不同流量工况下压力脉动时域图、频域图、静压分布和速度分布,发现在0.2Qn和0.4Qn的小流量工况下,流体流向分布极不均匀,有明显的侧向流动存在,甚至还可发现回流,这说明小流量工况有较多的涡流区域和二次流;随着流量增大,其流速分布较为稳定,压力脉动也随之减小。这一研究成果在某种程度揭示了双吸离心泵压力脉动随着流量增大而减小的原因。本文取得的研究成果,为改善双吸离心泵水力设计、提高运行稳定性具有指导意义。
[Abstract]:Double suction centrifugal pump is widely used in water conservancy, agriculture and energy and chemical engineering. Double suction centrifugal pump pressure pulsation and vibration, noise, cavitation and other closely related, is the typical one of the non steady state operating characteristics. In this paper, through the design, manufacture 5 different blade stagger angle of the double suction centrifugal pump, and experimental research and calculation of CFD system, the system reveals the influence of centrifugal pump pressure pulsation and hydraulic characteristics of double suction staggered blade. A typical double suction centrifugal pump test device was established, according to the 5 kinds of leaves under different scenarios and the stagger angle (0 degrees, 12 degrees, 24 degrees, 36 degrees and 48 degrees) in different flow conditions of pressure fluctuation test study, the relationship of each measuring point of pressure pulsation and blade stagger angle. The results show that: (1) the blade stagger angle have no effect on the double suction centrifugal pump lift and efficiency. (2) the pressure pulsation suction chamber in space Uniform distribution, the maximum fluctuating in diaphragm position. The suction chamber pressure pulsation is influenced by impeller rotation effect is large, in the frequency of blade performance for harmonic frequency and 1/2 times of the rotational frequency of the impeller blade passing frequency. Staggered less influence angle on the suction chamber. The pressure fluctuation amplitude (3) angle has great influence on the pressure of water room pressure pulsation staggered blade, especially the effect of blade frequency amplitude significantly. Compared with test result of different schemes, when the blade stagger angle is nearly uniform staggered (360 degrees /2*N), water pressure chamber pressure distribution is more uniform, the lowest pressure pulsation, non staggered impeller can be reduced by more than 50% (4) were established. The relationship between the flow and pressure pulsation. In the normal operating range (0.6Qn to 1.2Qn), the pressure fluctuation is small, increases in pressure and small flow pulsation zone, the suction chamber in the 0.2Qn and 1.2Qn conditions, the 1/2 blade frequency pressure fluctuation coefficient Which is 3.86 times the rated load amplitude and 1.11 times; in the water pressure chamber, the pressure pulsation frequency of blade frequency, in 0.2Qn and 1.2Qn conditions, the frequency of the maximum pressure fluctuation coefficient is respectively 0.98 times rated amplitude and 2.01 times. To carry out the numerical study of double suction centrifugal pump in the pressure fluctuation characteristics of different the leaves staggered angle, the double suction centrifugal pump pressure pulsation energy characteristics and simulation results are consistent with the experimental results. Through the analysis of pump flow graph in time domain, frequency domain, pressure distribution and vortex structure with staggered blade angle change process and change that the pressurized water chamber and the impeller flow field in the middle the vortex intensity with the blade angle shift from non staggered to close and uniform interleaving scheme gradually weakened, formed by the jet outlet of impeller wake flow has been reduced two times, which is caused by the double suction centrifugal pump pressure pulsation with staggered vanes The main reason of the change. The double suction centrifugal pump flow and pressure pulsation of the relationship between the numerical study, by analyzing the different flow conditions of pressure fluctuation time domain diagram, frequency chart, static pressure distribution and velocity distribution, found in the small flow condition of 0.2Qn and 0.4Qn, the flow distribution is very uneven, there are the lateral flow significantly, and even found the back, indicating that eddy current region small flow rate condition more and two flow; as the flow rate increases, the velocity distribution is relatively stable, the pressure fluctuation is also decreased. The results of this study revealed a double suction centrifugal pump with pressure pulsation flow increases to a certain degree of reason research results of this paper, in order to improve the double suction centrifugal pump hydraulic design, has a guiding significance to improve the operation stability.

【学位授予单位】：中国农业大学
【学位级别】：博士
【学位授予年份】：2017
【分类号】：TH311

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