超低比转数离心鼓风机的实验研究和数值模拟

发布时间：2018-04-14 12:38

本文选题：比转数 + 叶片型线　；参考：《上海交通大学》2012年硕士论文

【摘要】：现有的热泵系统主要应用于食品加工、化纤制造和木材加工等行业的干燥循环系统,而超低比转数离心鼓风机是该系统最关键的设备之一。该类风机的特点是小流量高压升,这种气动特性决定了其极低的比转数。因此该类风机设计时只能采用窄叶轮结构,这就使得其内部的壁面粘性效应和流动分离现象显著,引起的流动损失将远大于正常叶轮宽度风机的损失,因此导致实际应用中效率往往低于传统风机。该类鼓风机应用广泛并且必须长年不间断地运行,加上实际应用效率较低,使其耗能巨大,因此提高其性能对节能环保有着重要的现实意义。对于离心风机,影响叶轮性能的因素有叶片型线以及叶轮宽度等。当叶片进口安装角一定时,叶片形状影响整个流道内的压力和速度分布,而压力速度的分布势必影响叶轮的性能。因此研究不同叶片型线叶轮及不同宽度叶轮内部的流动情况,探索叶轮内流场的流动机理,对于提高其性能具有重要的作用。因此本文将主要研究焦点定位于叶片型线和叶轮宽度对超低比转数离心鼓风机性能的影响。本文根据工程中现有应用比较广泛的某一超低比转数离心鼓风机,设计了一个具有同样流量系数和压升系数的风机模型进行研究。在一定的参数下设计了3种不同型线的叶片,即前弯叶片、后弯叶片和变厚度前弯叶片。首先本文对3种叶型叶轮进行性能实验研究,测得了3种叶轮分别在4个转速下的10个流量工况的性能数据,并通过相似原理进行曲线拟合,得到了3种叶片的性能曲线。以此为依据,分析了3种不同型线叶片的性能差异。结果显示楔形叶片在3种叶片中具有相对较好的性能,而传统风机常使用的后弯叶片的性能并不占优。为了进一步分析叶片型线对超低比转数离心鼓风机产生性能差异的原因,本文又对3种叶轮进行可视化流动实验。在流道中均匀分布7组示踪排线,通过示踪排线的指示方向来判断当地位置气流的方向,借助对叶轮流道内部气流直观的流动观察来分析叶片型线对流道内部气流的影响情况,以此来部分解释性能差异的原因。由于可视化流动实验条件的限制,并不能获得完整的流场信息。因此本文对离心鼓风机模型进行全三维整机CFD计算,通过对风机内部流场的模拟来深入的分析不同叶片型线风机产生性能差异的机理。结果显示后弯叶片的受到的壁面的粘性效应和分离现象显著,由此产生的回流现象明显;楔形叶片在前弯叶片的基础上通过优化得到,在一定程度上改善了由于叶轮流道过窄而产生的流动分离效应,使该类风机具有较好的效率。通过对不同叶片型线的叶轮进行研究发现通过改变叶片型线仅在一定程度上改善了由于叶轮流道过窄而产生的粘性效应增强和流动分离现象。由此可见叶轮宽度对该类风机的性能具有很大的影响。本文进一步又对不同宽度的叶轮进行数值研究。改变叶轮宽度可能导致出口流量和压升产生一定的变化,从而偏离设计工况。因此,可以寻求一个合适的叶轮宽度,使得该风机在一定的设计工况偏离值内获得最优的总体性能。
[Abstract]:The existing heat pump system is mainly used in food processing, circulation system of dry chemical fiber manufacturing and wood processing industries, and super low specific speed centrifugal blower is one of the most important equipment in the system. The blower has the characteristic of small flow and high pressure rise, the aerodynamic characteristics determine its very low specific speed. Therefore the design of this kind of fan only by narrow impeller structure, which makes the internal wall viscous effect and flow separation phenomenon significantly, flow caused by the loss will be greater than the normal fan impeller width loss, therefore leads to the actual application efficiency is often lower than the traditional blower. The blower is widely used and not for many years continuous operation, and the actual application efficiency is low, the energy consumption is huge, so improve its performance has important practical significance to energy saving and environmental protection.
For the centrifugal fan, factors affecting the performance of the impeller blade and impeller width. When the blade installation angle when the influence of the pressure and velocity distribution of the whole passage shape of the blade, and the pressure and velocity distribution of impeller is bound to affect the performance. Therefore research on the internal flow of different leaf types and different line width of impeller the impeller, exploring of impeller flow mechanism, plays an important role in improving the performance. So this paper will mainly focus on the profile of the blade and impeller width on the ultra-low specific speed centrifugal blower.
According to a comparison of a wide range of existing application of low specific speed centrifugal blower, a design with the same flow coefficient and pressure coefficient of the wind turbine model is studied. With certain parameters designed 3 different blade profile, the blade, blade and variable thickness after bending before curved blade.
Firstly, experiments were carried out to study the performance of 3 kinds of blade impeller, the performance data measured 3 kinds of impeller in 4 speed under 10 flow conditions, and the curve fitting by similarity principle, the performance curves of the 3 leaves. On this basis, analyzes the differences between the performance of 3 different type linearifolia tablets the results showed that with relatively good performance in the 3 wedge blade in the blade and blade often uses the traditional performance of the fan is not dominant. In order to further analyze the blade profile of super low specific speed centrifugal blower performance difference, for the flow visualization experiment of 3 kinds of impeller 7. Group tracing distribution cable in the flow passage, through the direction of tracing cable to determine the local position of the direction of air flow, the flow of air flow in the impeller visual observation to analyze the blade profile of the internal gas flow The influence of the flow is explained in part to explain the reasons for the difference in performance.
Because the condition of flow visualization experiment limit, and can not get the information flow integrity. The centrifugal blower model full 3D machine CFD calculation, through the simulation of the internal flow field of the fan blade type line to in-depth analysis of different wind turbine performance difference mechanism. The results show significant blade by the wall the effect of viscosity and separation, resulting reflux is obvious; wedge blade optimization based on the obtained by curved blades, is improved to a certain extent due to narrow impeller flow separation effect, so the blower has better efficiency.
Study found that the viscous effect by changing the blade type line only improved to a certain extent due to narrow impeller enhancement and flow separation phenomenon through the impeller of different blade type line. Thus the impeller width has great influence on the performance of the fan. The paper further on the different width of the impeller was numerically study. Different impeller width may lead to outlet flow and pressure change to deviate from the design condition. Therefore, you can look for a suitable impeller width, the fan in the design condition certain deviation from the best overall performance value.

【学位授予单位】：上海交通大学
【学位级别】：硕士
【学位授予年份】：2012
【分类号】：TH442

【参考文献】