摘 要

随着缸内直喷技术在汽油发动机上的应用推广，缸内气流对喷雾质量的影响尤为突出。由于缸内气流动的不确定性，直接测试很难探明缸内气流与喷雾质量的关系。因此采用实验手段，用带压力的风洞模拟缸内气流条件进行基础实验分析，可以有效地确认各流场条件对喷雾特性的影响。为此，本文专门设计了试验段尺寸为100mm×100mm的回流式低速压力风洞。

本文主要对其内部结构进行结构设计，对风洞的气动特性进行分析。在风洞结构设计部分：收缩段分别采用双三次曲线、五次方曲线和维氏曲线参数进行设计，获得了三组不同的收缩段结构，并使用Solidworks分别建立不同的收缩段流场模型，使用Fluent进行数值模拟仿真，比较其速度、静压、湍流度等流动特性参数，计算表明双三次曲线构成的收缩段具有最好的流场品质；拐角处导流片采用双圆弧翼型导流片和薄片式导流板分别使用等距分布和算术级分布进行初始设计，建模得到不同的流场模型，数值模拟仿真发现采用双圆弧翼型按等距分布排列导流效果较为理想。根据仿真结果，完成了各个部分结构的零件和装配体的设计，在尽量不影响精度的情况下，优化设计，简化加工，降低加工成本。

本文旨在设计出回流式低速高压风洞的内部结构，提高流场品质，满足科研工作的基本需要，可用于一些空气动力学模拟实验。

关键词：压力风洞；流场分析；结构设计；数值模拟

Abstract

With the direct injection technology in the gasoline engine on the application of the promotion, the cylinder air flow on the spray quality is particularly prominent. Due to the uncertainty of the cylinder flow, it is difficult to directly test the relationship between the air flow and the spray quality. Therefore, it is effective to confirm the influence of the flow conditions on the spray characteristics by using the experimental method to simulate the cylinder airflow condition with the pressure wind tunnel. In this paper, the design of the test section size of 100mm × 100mm reflux low pressure wind tunnel.

In this paper, the internal structure of its structure design, the wind tunnel of the aerodynamic characteristics of the analysis. In the design part of the wind tunnel, the three sections of different shrinkage sections are obtained by using the cubic curve, the cubic curve and the Vickers curve parameters respectively. The different flow field models are established by Solidworks, The flow characteristics of velocity, static pressure and turbulence are calculated by using Fluent. The calculation results show that the contraction section of the double tricus curve has the best flow field quality. The guide plate at the corner is made of double circular wing The flowmeter and flap baffle are designed by equidistant distribution and arithmetic grade distribution respectively. The different flow field models are modeled. The numerical simulation shows that the double-circular airfoil is ideal for equidistant distribution The According to the simulation results, the design of the parts and assemblies of each part structure is completed. The optimized design simplifies the processing and reduces the processing cost without affecting the precision.

The purpose of this paper is to design the internal structure of the return - type low - speed and high - pressure wind tunnel, improve the quality of the flow field and meet the basic needs of the research work, and can be used in some aerodynamic simulation experiments.

Key Words：wind tunnel；flow field；structural design；numerical simulation

目 录

摘 要 I

Abstract II

第1章 绪论 1

1.1风洞的简介 1

1.2风洞的发展与国内外研究现状 2

1.3本文的主要研究内容 3

1.4本实验平台的意义 3

第2章 流体力学相关基础及相关分析软件介绍 4

2.1 流体力学相关基础 4

2.1.1流体力学基本守恒定律 4

2.1.2湍流模型 5

2.2软件简介 6

第3章 闭路式回路风洞关键部位结构设计 7

3.1收缩段结构设计 7

3.1.1收缩段曲线长度确定 8

3.1.2各种收缩段曲线的参数与取值 8

3.1.3各种收缩段曲线的仿真比较 9

3.1.4收缩段结构设计 13

3.2拐角导流片结构设计 15

3.2.1导流片几何形状 15

3.2.2导流片排列顺序 18

3.2.3拐角导流片机械结构 21

3.3蜂窝器设计 22

第4章 全文总结 23

参考文献 24

致谢 26

第1章 绪论

1.1风洞的简介

风洞（wind tunnel），是通过人工产生和控制气流，以模拟飞行器或物体周围气体的流动，研究气流对物体的作用并观察物理现象的一种管道状实验设备，它是进行空气动力试验最常用、最有效的工具^[1]。

风洞的种类按照试验速度划分可以分为亚声速风洞，跨声速风洞，超声速风洞和高超声速风洞^[2]。风洞试验段的马赫数小于0.7的风洞为亚声速风洞，跨声速风洞试验段马赫数为0.5-1.3，超声速风洞试验段马赫数为1.5-4.5，风洞实验段马赫数大于4.5的被称为高超声速风洞。

低速风洞也属于亚声速风洞，其试验段马赫数低于0.4，计算时可以忽略其内空气的压缩性，从结构形式上来说，低速风洞可以分为开路式风洞和闭路式回路风洞^[3]。