离心泵叶片型线对泵性能影响的研究

发布时间：2018-05-02 14:11

本文选题：离心泵 + 叶片型线　；参考：《兰州理工大学》2011年硕士论文

【摘要】：离心泵广泛应用于工农业生产和居民生活的各个领域。据统计,每年消耗在泵类产品上的电能约占全国总发电量的20%左右。同时,目前我国生产的泵的效率与国外工业发达国家相比仍有一定的差距。因此,研究提高离心泵的效率,降低能耗,对国民经济的发展和实现节能减排都具有十分重大而深远的意义。叶轮是离心泵的核心部件,叶片形状是决定泵性能的关键因素之一。因此离心泵叶轮叶片型线设计直接影响水泵的性能。目前的工程实际中在流面上绘制叶片型线时,仍以保角变换法进行叶片绘型。这些方法具有精度低,对设计人员个人经验依赖较大,而且有难以保证叶片安放角按要求规律变化等不足。其一,叶片出口边是否选在一个轴面上有一定的随意性,即叶片出口边倾角γ的取值是随意的;其二,叶片包角的确定有很大的随意性;其三,方格网上的叶片展开流线的安放角的变化规律有一定的随意性。因而有必要对叶片的型线进行研究,找寻更为精确的确定叶片型线的方法。本文分别以叶片出口边倾角γ、叶片包角为对象,研究叶片型线对泵性能的影响。本文的工作主要有以下几个方面: 1、推导出了确定叶片包角取值范围的公式。在此基础上,提出了利用Bezier曲线绘制及其调控叶片展开流线的方法。这样不仅保证叶轮叶片展开流线单调光滑而且叶片安放角可以按要求规律变化,还可以使叶片展开流线的设计和修改方便,提高了绘制效率。 2、通过对所设计的泵进行数值模拟,分析内部流场可得:叶轮内工作面相对速度较小,背面相对速度较大;从工作面到背面,相对速度的大小变化较快;叶轮内没有出现边界层分离;各工况下叶轮内的静压从叶轮进口到出口均逐渐增加;随着流量的增大,叶轮出口的静压减小。 3、在叶轮基本外尺寸确定的情况下,保持叶片包角和叶片安放角的变化规律不变,通过改变叶片出口边倾角进行叶片型线的研究。对于比转速为98的泵ZA150-315确定了三个叶片出口边倾角分别为:62°、76°、90°;对于比转速为188的泵ZA150-200确定了三个叶片出口边倾角分别为:69°、79°、90°;对于比转速为78的泵TTMC-125也确定了三个叶片出口边倾角分别为:64°、77°、90°。利用本文提出的绘制及调控叶片展开流线的方法进行叶轮水力设计,并得到实体模型。利用FLUENT 6.3.26软件对上述设计的叶轮进行流场模拟计算,得到了泵的性能曲线。经对比分析:ZA150-315的叶片出口边倾角为76°的叶轮性能优于62°、90°的叶轮;ZA150-200叶片出口边倾角为69°的叶轮能量性能好于79°、90°的叶轮;TTMC-125叶片出口边倾角为64°的叶轮能量性能好于77°、90°的叶轮。由离心泵的特性曲线可知,每个叶轮都有一个合适的叶片出口倾角。 4、在叶轮基本外尺寸确定的情况下,保持叶片出口边倾角、叶片安放角的变化规律等因素不变,对叶片包角进行研究。本文以泵ZA150-315为例,在轴面投影图不变的情况下,选择最优的叶片出口边倾角76°进行设计。根据本文提出的确定包角取值方法,确定叶片包角分别为:180°、195°、210°,并分别进行叶轮设计得到叶轮的实体模型。经过数值模拟发现ZA150-315叶片包角为195°时,叶轮的效率最高。包角为195°的叶轮效率比包角为180°、210°的叶轮高3%左右,同样,对于每个叶轮也有一个最佳的叶片包角。证明了本文提出的确定包角方法的可行性。
[Abstract]:Centrifugal pumps are widely used in various fields of industrial and agricultural production and resident life. According to statistics, the electricity energy consumed on the pump products accounts for about 20% of the total electricity generation in the country every year. At the same time, the efficiency of the pump produced in our country still has a certain gap compared with that of the developed countries. Therefore, the efficiency of the centrifugal pump is improved and the efficiency of the pump is reduced. Consumption is of great and far-reaching significance to the development of national economy and the realization of energy conservation and emission reduction.
The impeller is the core component of the centrifugal pump, and the blade shape is one of the key factors to determine the performance of the pump. Therefore, the design of the blade profile of the centrifugal pump impeller directly affects the performance of the pump. In the current engineering practice, the blade profile is still made by the conformal transformation method when the blade profile is drawn on the flow surface. These methods have low precision and are designed for the designers. In addition, it is difficult to ensure that the blade placement angle changes according to the requirement law. First, whether the blade exit edge is selected on an axis is random, that is, the value of the angle of the blade exit angle is random; secondly, the determination of the blade angle is very random; thirdly, the blade of the grid is unfolding. It is necessary to study the blade profile and find a more precise method to determine the blade profile. This paper studies the effect of blade profile on the performance of the pump. The main work of this paper is to study the effect of the blade profile on the performance of the pump.
1, the formula to determine the range of the value of the blade angle is derived. On this basis, a method of drawing and adjusting the flow line of the blade by using the Bezier curve is put forward, which not only ensures the monotonous smooth flow line of the impeller blade, but also changes the angle of the blade placement angle according to the requirement law, and can also design and modify the flow line of the blade. Thus, the efficiency of drawing is improved.
2, through the numerical simulation of the designed pump, the internal flow field can be analyzed. The relative velocity of the working face in the impeller is relatively small and the back velocity is relatively high; the relative velocity varies rapidly from the working face to the back; there is no boundary layer separation in the impeller; the static pressure in the impeller increases gradually from the impeller inlet to the outlet under various working conditions; With the increase of flow rate, the static pressure of the impeller outlet is reduced.
3, when the basic outer size of the impeller is determined, the change law of the blade angle and the blade angle is kept constant, and the blade profile is studied by changing the angle of the blade outlet. For the pump ZA150-315 with a specific speed of 98, three blade outlet angles are determined to be 62, 76, 90; for a pump with a specific speed of 188, it is true. Three blade outlet angles are determined as 69, 79, 90 degrees, and for the pump TTMC-125 with a specific speed of 78, three blade outlet angles are also determined to be 64, 77, 90 degrees respectively. The hydraulic design of the impeller is made by using the method proposed in this paper and the method of regulating the blade expansion flow, and the solid model is obtained by using the FLUENT 6.3.26 software. The flow field simulation of the designed impeller is calculated and the performance curve of the pump is obtained. After comparison and analysis, the impeller with 76 degree angle of ZA150-315 blade outlet angle is superior to 62 degree, 90 degree impeller, and the impeller of ZA150-200 blade outlet angle is 69 degrees, and the impeller with 79 degrees, 90 degrees is better than the impeller of TTMC-125 blade outlet angle of 64 degrees. The performance of the impeller is better than 77 degree and 90 degree. According to the characteristic curve of the centrifugal pump, each impeller has a suitable outlet angle.
4, in the case of determining the basic outer size of the impeller, the angle of the blade is kept unchanged, and the blade angle of the blade is kept constant. This paper takes the pump ZA150-315 as an example, and chooses the optimal blade outlet angle of 76 degrees under the condition of the axis plane projection. It is determined that the blade angle is 180 degrees, 195 degrees and 210 degrees respectively, and the impeller is designed to get the solid model of the impeller respectively. After the numerical simulation, it is found that the efficiency of the impeller is the highest when the angle of the ZA150-315 blade is 195 degrees. The efficiency of the impeller with the angle of 195 degrees is 180 degrees, and the impeller height of 210 degrees is about 3%, as well as for each impeller. An optimal blade wrapping angle proves the feasibility of the proposed method.

【学位授予单位】：兰州理工大学
【学位级别】：硕士
【学位授予年份】：2011
【分类号】：TH311

【参考文献】