基于中轴变换的叶片泵轴面流道设计方法

发布时间：2018-07-07 23:49

本文选题：叶片泵 + 轴面流道　；参考：《浙江大学》2013年博士论文

【摘要】：轴面流道设计是整个泵水力设计的基础和重要组成部分,本文对叶片泵轴面流道的设计进行了研究。首先简要论述了离心泵轴面流道的设计思想、设计目标,首次从几何描述体系这一新的角度对文献中出现的众多轴面流道设计方法加以归纳总结,最终把几何问题还原为流动问题并评价不同几何方法的优劣；提出基于过流面积计算的一个优秀的轴面流道设计方法所应满足的三个必要条件,并藉此提出本课题的研究内容。首次提出基于中轴变换的轴面流道设计方法,实现以叶片泵为代表的透平机械轴面流道反设计。基于中轴变换完成了轴面流道前后盖板型线的统一数学描述,给出了相应的矢量表达式和标量表达式；藉此推导出圆弧假设下的过流面积的近似解析表达式和精确解析式,并基于泰勒展开对这两种计算公式的一致程度加以分析,指出两者的近似条件；通过对过流面积计算公式的研究,发现基于过流面积的轴面流道设计中只存在两个独立的变量,因而需要给出两个独立的方程,其中一个方程由期望的过流面积分布方程(目标方程)给出,而另一方程则由约束方程给出；为方便施加基于几何或流动的约束,推导出轴面型线的曲率方程,分别给出曲率形式和笛卡尔形式的几何约束表达式；基于流动分析,给出压力平衡通道的约束表达式,并建立了约束的普遍形式；从而建立了基于中轴变换的轴面流道的设计体系。提出了基于中轴变换的轴面流道统计方法,实现轴面流道全尺寸的统计。传统的轴面流道形状统计方法无法做到整个轴面流道全尺寸的统计,虽得以窥探轴面流道随比转速的大体变化规律,但其中变化的细节仍未可知。本文突破了传统轴面流道统计方法中只关注具体某几个尺寸的思维限制,将前后盖板型线的统计通过中轴变换转换为等价变量的统计；通过一个泵型统计实例从统计样本、统计方法、统计规律和基于泵型统计的轴面流道设计这四个方面对首次由作者提出的基于中轴变换的轴面流道统计方法进行了介绍。发现所统计的泵型中内切圆圆心轨迹和半径都是光滑的曲线,没有明显特征,但a和θ分布曲线呈现出明显的分段特征,且每一段都可由直线或抛物线很好地拟合；因此通过对α和θ曲线各段拟合系数及间段点的统计,经反变换完成对前后盖板型线全尺寸的统计；在统计中采用了无量纲处理技术和平均化技术,以减小样本的选择带来的统计误差。研究了基于过流断面的轴面流道设计基础。基于过流断面的轴面流道设计是在一系列假设的基础上发展起来的,首次通过平均轴面速度的设计分布与CFD计算分布的对比开展设计基础的研究；从不同方面对比了平均轴面速度的期望分布、设计分布、经厚度修正的设计分布、经面积平均的计算分布、经流量平均的计算分布,分析了这些假设的适用情况,发现：1)在叶片安装角设计得较为合理的情况下,在设计工况下轴面流道的一维流动假设即便对高比转速混流泵也是适用的；2)叶片厚度在轴面流道设计中不应忽略,可通过引入叶片厚度引起的流道阻塞系数,对过流面积进行修正；3)对可压缩气体,可引入反映当地压缩程度的系数对平均轴面速度进行修正；4)过流断面的圆弧假设即便对高比转速混流泵也是适用的。开展了基于中轴变换的核主泵叶轮和导叶轴面流道一体化设计研究。以AP1000核主泵水力参数为例,介绍了基于中轴变换的核主泵叶轮和导叶轴面流道一体化设计流程,分别开展了不考虑叶片厚度的轴面流道设计和考虑叶片厚度的轴面流道设计,表明：1)不考虑叶片厚度的设计,轴面速度CFD计算分布在叶轮和导叶叶片进出口边存在较大的速度突变；2)考虑叶片厚度的设计,能很好抑制叶轮和导叶叶片进出口边的轴面速度突变；3)轴面速度在叶片进出口边的突变对水力效率影响不显著；4)通过CFD计算分布与设计分布的对比,可定量评判叶片安装角设计的合理程度；5)本文提出的基于中轴变换的轴面流道设计方法能很好地应用于核主泵叶轮和导叶轴面流道的设计。
[Abstract]:The design of axial flow channel of vane pump is studied in this paper . First of all , the design idea and design goal of axial flow channel of centrifugal pump are discussed . First , the design method of axial flow channel in the literature is summarized from this new angle of geometry description system . Finally , the geometric problems are reduced to flow problems and the advantages and disadvantages of different geometric methods are evaluated .
In this paper , three necessary conditions for designing an excellent axial flow path design method based on over - flow area calculation are presented , and the research contents of this subject are proposed .

The design method of axial flow channel based on mid - axis transformation is proposed for the first time , and the inverse design of axial flow channel of turbine machinery represented by vane pump is realized . The uniform mathematical description of the front and rear cover plate line of axial flow channel is completed based on the middle axis transformation , and the corresponding vector expression and scalar expression are given .
The approximate analytical expression and exact analytic formula of the over - flow area under the assumption of circular arc are derived , and the consistency degree of these two formulas is analyzed based on Taylor expansion , and the approximate conditions are pointed out .
It is found that only two independent variables exist in the design of the axial flow path based on the over - flow area , and two independent equations are given . One of the equations is given by the expected flow area distribution equation ( objective equation ) , while the other equation is given by the constraint equation ;
In order to facilitate the application of geometric or flow - based constraints , the curvature equations of the axial line are derived , and the geometric constraint expressions in the form of curvature and Cartesian form are given .
Based on the flow analysis , the constraint expression of the pressure balance channel is given , and the general form of the constraint is established .
Therefore , the design system of axial flow channel based on middle axis transformation is established .

This paper presents a statistical method of axial flow channel statistics based on mid - axis transformation , which can be used to calculate the full - size of axial flow channel . The traditional axial flow channel shape statistics method can not be used to calculate the whole size of the axial flow channel , but the details of the variation are still unknown . The paper breaks through the thinking limitation of the specific dimensions in the traditional axial flow channel statistics method , and converts the statistics of the front and rear cover plate type lines into equivalent variables by the intermediate - axis transformation .
Based on the statistical sample , the statistical method , the statistical law and the design of the axial flow channel based on the pump - type statistics , this paper introduces the statistical method of the axial flow path based on the mid - axis transformation proposed by the author in this paper . It is found that the circular center trajectory and radius of the inscribed circle in the pump type are smooth curves and have no obvious characteristics , but the a and 胃 distribution curves show obvious segmentation characteristics , and each segment can be well fitted by a straight line or a parabola ;
Therefore , through the statistics of the fitting coefficient and the inter - segment point of each segment of the alpha and theta curves , statistics of the full - size of the front and rear cover plate type lines are completed through inverse transformation ;
Nondimensional processing techniques and averaging techniques are used in statistics to reduce the statistical errors caused by the selection of samples .

On the basis of a series of assumptions , the design basis for the first pass of the design distribution of the average axial velocity and the distribution of CFD calculation is studied .
The expectation distribution , design distribution , design distribution of the average axial surface velocity , the calculation distribution of the area average , the calculation distribution of the flow average and the calculation distribution of the flow average are compared from the different aspects , and the application of these assumptions is analyzed through the calculation of the flow average .
2 ) the blade thickness should not be neglected in the design of the axial flow passage , and the flow passage blocking coefficient caused by the thickness of the blade can be introduced , and the over - flow area is corrected ;
3 ) the average axial surface velocity can be corrected by introducing a coefficient reflecting the local compression degree to the compressible gas ;
4 ) Circular arc assumption of over - current cross section is applicable even for high specific speed mixing pump .

The integrated design of the impeller and guide vane axial flow path of the nuclear main pump based on the middle axis transformation is carried out . Taking the hydraulic parameters of the nuclear main pump of the AP1000 as an example , the design of the axial flow path based on the middle axis transformation and the axial flow channel design of the guide vane are introduced . The design of the axial flow path without considering the blade thickness and the design of the axial flow channel considering the blade thickness are carried out respectively .
2 ) considering the design of the blade thickness , the axial surface speed change of the impeller and the inlet and outlet edge of the guide vane blade can be well inhibited ;
3 ) the abrupt change of the axial surface velocity on the inlet and outlet sides of the blade is not significant to the hydraulic efficiency ;
4 ) According to the comparison between the distribution of CFD and the design distribution , the reasonable degree of the design of the blade installation angle can be quantitatively judged ;
5 ) The design method of axial flow channel based on mid - axis transformation proposed in this paper can be applied to the design of impeller and guide vane axial flow channel of nuclear main pump well .
【学位授予单位】：浙江大学
【学位级别】：博士
【学位授予年份】：2013
【分类号】：TH31

【参考文献】