单流道离心泵非定常特性及水力设计方法研究

发布时间：2018-02-15 11:56

  本文关键词： 单流道离心泵 水力设计 非定常特性 滑移系数 同步测试　出处：《江苏大学》2015年博士论文　论文类型：学位论文

【摘要】：本文的研究是在国家科技支撑计划(2013BAK06B02)的资助下开展的。随着建设生态中国和加快环境治理的发展,单流道离心泵在污水污物和无堵塞输送方面得到了广泛的应用,但在能耗高和运行平稳性差方面还有很多难题需要研究。为了提高单流道泵运行的效率和稳定性,进一步丰富和发展单流道泵的水力设计方法,本文采用试验测试、数值计算和理论分析相结合的方法对单流道泵的非定常运行特性和水力设计进行了深入研究。主要工作和创造性成果有：1.搭建了单流道离心泵能量性能和非定常特性的同步测试台,开展了能量性能、扬程脉动、压力脉动和径向力的试验研究。试验发现：(1)单流道泵的扬程具有强烈的非定常特性,设计工况下扬程脉动量是平均扬程的26.6%；(2)当泵的工况由0.6Qd增大到1.4Qd时,扬程极小值出现的叶轮旋转角度由43°逐渐增大到60°,扬程极大值出现的叶轮旋转角度由280°逐渐减小至268°；(3)当叶片出口边刚好通过隔舌位置时,蜗壳第8断面处的压力脉动出现峰值,随着叶轮的旋转,从蜗壳的第8断面到第1断面逐渐出现压力脉动峰值；(4)时均径向力随流量的增大呈先减小后增大的趋势,最小值出现在最优工况,当泵的工况由0.4Qd增大到1.4Qd时,时均径向力方向由蜗壳隔舌下游265°逐渐增大至隔舌下游272°。2.基于试验对单流道泵复杂内流CFD计算方法进行了验证,并对叶轮内的流动特性进行了分析。(1)单流道离心泵内流数值模拟应采用非定常计算方法求解,其中小流量工况的内流CFD计算可采用SST k-ω模型,其它工况可采用k-ε模型；(2)当叶片出口边与蜗壳隔舌相对位置由0°旋转到325°时,叶轮出口处高压区的周向位置由40°增大至330°,高压区始终位于叶片出口边的下游位置；(3)小流量工况时,叶片进口边下游压力面流道内出现较严重的流动分离和回流现象。3.针对单流道离心泵强烈的非定常特性,基于Backstrom的单相对涡假设对Busemann滑移系数理论解中的h0和cm进行了数学建模,首次建立了单流道叶轮全流量范围内滑移系数的求解公式,并用一台比转速ns=140的单流道离心泵对滑移系数进行了试验验证。结果表明：(1)建立的数学模型与理论解具有较好的一致性,其中h0的数学模型在β2B≥40°时比Wiesner解的精度更高；(2)全流量范围内滑移系数的计算结果与试验值基本一致,最大偏差仅为5.05%。4.应用本文建立的单流道叶轮全流量滑移系数求解公式和能量损失模型,提出了一种单流道离心泵能量性能预测模型,并用2台单流道泵进行了试验验证。结果表明该模型能够较为准确地预测单流道泵扬程、功率和效率等性能,最大偏差在6%以内。5.改进了单流道叶轮的水力设计方法。基于建立的能量性能预测模型,根据输送颗粒最大直径、设计工况扬程和电机最大配套功率的约束条件,以机组效率最高为设计目标,对单流道叶轮主要几何参数的计算方法进行了改进；首次针对“薄壁型”单流道叶轮提出了一种全单调的叶片型线函数,针对“厚壁型”单流道叶轮提出了一种流道中线方程,对单流道叶轮的绘型方法进行了改进。国内外同类产品的性能对比表明,采用改进水力设计方法两组叶轮的泵效率已达到国际先进水平。6.基于试验和CFD研究了叶片型线函数、叶片出口平均安放角β2B和叶片包角εsb对能量性能的影响。结果表明(1)采用全单调型线函数、减小β2B以及减小叶片出口边吸力侧安放角β2SB可以降低叶轮出口混合损失和叶轮内的水力损失,εsb对叶轮出口混合损失的影响较小,但增大εsb能够降低叶轮内的水力损失；(2)随着β2B的减小,扬程流量曲线呈陡降趋势,功率流量曲线呈现无过载特性；(3)随着β2B由80增大到250,泵的扬程和功率逐渐增大,效率先增大后减小,效率最大增加了7个百分点；随着β2SB由24°增大到42°,扬程和功率逐渐增大,效率逐渐减小,效率最大减小了1.8个百分点；随着εsb由290°增大到3900,功率逐渐减小,扬程和效率逐渐增大,效率最大增加了7.79个百分点。7.基于试验测量了叶片出口安放角和叶片包角对扬程脉动、压力脉动和径向力的影响。结果表明：(1)扬程极大值的时域分布以及径向力的方向主要受叶片出口边压力侧安放角β2BPB的影响,受β2BB和εsb的影响较小,随着β2PB由8°增大到25°,扬程极大值在时域上逐渐滞后,径向力方向指向的周向角度逐渐减小；(2)随着β2B由8°增大到25°、β2SB由24°增大到42°以及εsb由390°减小到290°,泵的扬程脉动、压力脉动和径向力逐渐增大,几何参数对扬程脉动和压力脉动影响程度从大到小依次为β2Bβ2SBεsb,对径向力影响程度从大到小依次为β2SBβ2Bεsb；(3)在保证单流道泵能量性能和颗粒通过性能的情况下,减小β2B和β2SB以及增大εsb有利于改善泵的非定常特性,提高单流道泵的运行稳定性。
[Abstract]:The research of this paper is in the national science and technology support program (2013BAK06B02) to carry out funding. With the development of the construction of ecological environment and accelerate the China governance, single channel of centrifugal pump has been widely used in sewage and non blocking conveyance, but in high energy consumption and stable operation of the poor there is still a lot of problems need to be studied. In order to improve the efficiency and stability of single channel pump operation, further enrich and develop the hydraulic design method of single channel pump, test using this method, numerical calculation and theoretical analysis of a combination of single channel pump unsteady operation characteristics and hydraulic design were studied. The main work and achievements are as follows: 1. set the energy performance of centrifugal pump of single channel and non synchronous test bench steady characteristics, to carry out energy performance, lift pulsation, experimental study on pressure fluctuation and radial force test found. : (1) single channel pump head with unsteady characteristics of strong lift, pulsating quantity under design conditions is the average lift 26.6%; (2) when the pump condition increased from 0.6Qd to 1.4Qd, the minimum value of the rotation of the impeller head angle from 43 degrees to 60 degrees increased gradually, the maximum lift impeller the rotation angle of 280 degrees by gradually reduced to 268 degrees; (3) when the blade outlet edge just through the tongue position, at the peak of the eighth volute cross pressure pulsation, along with the rotation of the impeller, volute from eighth to first section section the gradual emergence of pressure fluctuation peak; (4) both with radial force the increase of flow rate first decreased and then increased, the minimum value appeared in the optimal condition, when the pump condition increased from 0.4Qd to 1.4Qd, when the direction of radial force by the volute tongue downstream 265 degrees increased gradually to 272 DEG.2. downstream of the tongue test on single channel pump flow complex internal flow based on CFD The calculation method was verified, and the flow characteristics of the impeller were analyzed. (1) should be used for calculation of unsteady flow numerical simulation method for single channel in the centrifugal pump, the small flow condition in CFD flow calculation can be used SST k- turbulence model, other conditions can be using the k- model (2); when the blade outlet edge and volute tongue relative position by rotating 0 degrees to 325 degrees, the impeller outlet pressure area of the circumferential position increased from 40 degrees to 330 degrees, high pressure area has always been at the downstream position of blade outlet edge; (3) at small flow condition, the downstream pressure surface of blade inlet edge flow appeared serious flow separation and recirculation phenomenon of.3. according to the unsteady characteristics of single channel pump strong, Backstrom phase of vortex assumption of Busemann slip factor theoretical solution in H0 and cm were studied based on mathematical modeling, first established the single channel impeller full flow range slip Formula of coefficient, and use a single channel than the rotation speed of the centrifugal pump ns=140 on slip coefficient were tested. The results showed that: (1) the establishment of mathematical model and theoretical solutions have good consistency, the mathematical model of H0 in beta 2B is not less than 40 DEG C than Wiesner and the precision is higher; (2) the results of the full flow range of slip coefficient is basically consistent with the experimental values, the maximum deviation is only 5.05%.4. single channel impeller based full flow slip coefficient formula and energy loss model, put forward the energy performance of a single pre runner centrifugal pump test model, and 2 sets of single channel pump experiment results show that the model can accurately predict the single channel pump head, power and efficiency, the maximum deviation of the improved hydraulic design method of single channel impeller within 6%.5.. The energy performance of the pre established measurement model based on According to the maximum diameter of particle, conveying, constraint conditions and design conditions lift motor maximum power matching, to set the highest efficiency as the design goal, the calculation method of main geometric parameters of single channel impeller was improved; first proposed a blade type line full monotonic function for thin-walled single channel impeller ", for" the thick wall type single channel presents a channel midline equation, the drawing method of single channel impeller was improved. Comparison show that the performance of similar products at home and abroad, the pump efficiency improvement of hydraulic design method of impeller two group has reached the international advanced level of.6. test and CFD were studied based on the blade type line function. The average effect of blade outlet installing angle beta 2B and blade angle epsilon sb on energy performance. The results show that (1) the monotone line function, reduce beta 2B and reduce the blade outlet edge suction Ce Anfang Angle of 2SB can reduce the hydraulic loss in the impeller and the impeller outlet mixing loss, epsilon sb has little effect on the impeller mixing loss, but the increase of epsilon sb can reduce the hydraulic loss in the impeller; (2) with the decrease of beta 2B, head flow curve is steep drop trend, power flow curve has non overload characteristics; (3) with beta 2B increased from 80 to 250, and the lift of the pump power increases, the efficiency increases first and then decreases, the maximum efficiency increased by 7 percentage points; with beta 2SB increased from 24 degrees to 42 degrees, the lift and power increased, efficiency decreased gradually, maximum efficiency decreases by 1.8 percentage points; with epsilon sb increased to 3900 by 290 degrees, power decreases gradually, the head and the efficiency increased gradually, the maximum efficiency increased by 7.79 percentage points of.7. measuring the outlet blade angle and blade angle on the head pulsation based on the influence of pressure fluctuation and radial force. 琛ㄦ槑锛，

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