无过载离心泵结构参数对性能的影响研究

发布时间：2018-03-31 02:11

本文选题：无过载　切入点：功率备用系数　出处：《兰州理工大学》2012年硕士论文

【摘要】：无过载离心泵是指：泵的轴功率曲线有极值，即泵的轴功率在全流量范围内（从零流量到最大流量）都小于等于所配用电动机的额定功率。在实际使用中为了减小配用电动机的额定功率，要求全流量范围内泵的最大轴功率是设计点轴功率的某一倍数关系（一般是1.05~1.2倍）。为了满足这一要求，保证泵的运行可靠性，国内外学者对高效无过载离心泵有了一定的研究。本文在前人研究成果的基础上，通过理论公式的推导，研究了无过载离心泵性能与设计参数的关系，，主要工作和研究成果有： 1.根据无过载离心泵最大轴功率与额定轴功率比值（功率备用系数K）的公式，在满足一定的条件下（叶片出口宽度符合低比转速离心泵的经验公式：b_2=00003752D_2n_s~(1.15)，此条件可以改变），通过推导得到：K值仅是比转速、叶片出口角和叶片数的函数，依此函数利用MATLAB软件编写程序，并绘出了不同叶片数下K值的三维曲面函数图像，以及在不同叶片数下K值关于叶片出口角和泵比转速的等高线。由等高线图可见：K值和叶片数关系不大，叶片出口角、泵比转速对K值影响较大；在相同的K值下，比转速越高，可取的最大叶片出口角越大。由等高线图可以根据比转速、K值选择合理的叶片出口角。 2.依上述函数及其等高线为依据，设计了三台不同比转速的无过载离心泵，分别为泵A（n_s=62）、B（n_s=53）、C（n_s=58）。利用Pro/E对所设计的三台无过载离心泵进行全流道建模，分别导入GAMBIT划分网格，利用FLUENT进行数值模拟。 3.通过数值模拟发现：设计的A、B、C三种不同比转速离心泵均具备了无过载性能，且由A、B两泵模拟得到的功率备用系数和其给定的功率备用系数基本吻合；而C泵其结果有一定差异。分析其误差原因是由于C泵的叶片出口宽度不符合推导上述函数的假定条件（即b_2=00003752D_2n_s~(1.15)）。 4.只要保证在泵设计时，其叶片出口宽度符合经验公式b=b_2=00003752D_2n_s~(1.15)，利用文中得到的函数关系式就可以成功的设计出功率备用系数符合设计要求的无过载离心泵；对于用其他方法设计的低比转速无过载离心泵，如果其设计参数满足条件（b_2=00003752D_2n_s~(1.15)），利用文中的得到的函数关系式就可以准确的计算出其功率备用系数。 5.实例证明：文中方法能够成功而快捷的实现无过载离心泵的设计，避免了传统方法叶片出口角选择的盲目性。
[Abstract]:Non-overload centrifugal pump means that the axial power curve of the pump has extreme value, That is, the axial power of the pump is less than or equal to the rated power of the motor used in the whole flow range (from zero flow to the maximum flow). In order to reduce the rated power of the motor in practical use, In order to meet this requirement, the maximum shaft power of the pump in the full flow range is a certain multiple of the shaft power at the design point (generally 1.05V 1.2 times). In order to meet this requirement, the pump is guaranteed to operate reliably. Scholars at home and abroad have a certain degree of research on high efficiency and no overload centrifugal pump. Based on the previous research results, through the derivation of theoretical formula, the relationship between the performance and design parameters of non-overload centrifugal pump is studied. The main work and research results are as follows:. 1. According to the formula of the ratio of maximum shaft power to rated shaft power (power reserve coefficient K) of non-overload centrifugal pump, Under certain conditions (the empirical formula of centrifugal pump with low specific speed for the width of blade outlet:: B _ S _ 2T _ 2T _ 2O _ 2 003752D _ 2N _ S _ T _ 2N _ S _ T), this condition can be changed. By deducing the function that the ratio K value is only the specific speed, the outlet angle of the blade and the number of blades, According to this function, the program is written by MATLAB software, and the 3D curved surface function image with K value under different blade number is drawn. From the contour diagram, we can see that the ratio of K to the number of blades is not related to the number of blades, the outlet angle of the blade and the specific speed of the pump have great influence on K value; at the same K value, the specific speed of the pump has a great influence on K value. The higher the specific speed is, the greater the optimum outlet angle of the blade is. According to the contour diagram, the reasonable outlet angle can be selected according to the specific rotational speed K value. 2. According to the above function and the contour line, three non-overload centrifugal pumps with different specific rotational speeds are designed, which are the pump Agnes, respectively. The whole channel model of the three non-overload centrifugal pumps designed by Pro/E is introduced into the GAMBIT grid, and the whole channel model of the three non-overload centrifugal pumps is constructed by using Pro/E. The numerical simulation is carried out by FLUENT. 3. Through numerical simulation, it is found that the designed three kinds of centrifugal pumps with different specific speeds have no overload performance, and the power reserve coefficients simulated by the two pumps are in good agreement with the power reserve coefficients given by the two pumps. The reason for the error is that the width of the vane outlet of the C-pump does not conform to the assumption of deducing the above function. 4. As long as the width of the vane outlet conforms to the empirical formula b / b / 2n003752D / D / s / d / 2nS / L / L / L, the power spare coefficient of the pump can be successfully designed by using the function relation obtained in this paper. For the non-overload centrifugal pump with low specific speed designed by other methods, if its design parameters satisfy the conditions of 200003752D, the power reserve coefficient can be accurately calculated by using the function relation obtained in this paper. 5. The example shows that the design of the centrifugal pump without overload can be realized successfully and quickly, and the blindness of choosing the outlet angle of the blade in the traditional method is avoided.
【学位授予单位】：兰州理工大学
【学位级别】：硕士
【学位授予年份】：2012
【分类号】：TH311

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