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The Development of Unstructured Mesh Technology for Viscous High Speed Flows

粘性高速流非结构化网格技术的发展

基本信息

批准号：
EP/F032617/1
负责人：
O Hassan
金额：
$ 94.38万
依托单位：
Swansea University
依托单位国家：
英国
项目类别：
Research Grant
财政年份：
2007
资助国家：
英国
起止时间：
2007 至无数据
项目状态：
已结题

来源：
https://gtr.ukri.org/projects?ref=EP%2FF032617%2F1
关键词：
Development Unstructured Mesh Technology Viscous

项目摘要

Traditional design of aerospace vehicles has involved the extensive use of wind tunnels to test different configurations and to finalise design. However, this is an expensive and lengthy process that also requires the use of specialist test facilities designed for particular flow speeds. With the advent of the computer a new technology has emerged over the last 20 years that provides a powerful tool to aid aerodynamic design. The equations that govern the movement of air have been known for several centuries. However, for general flows, their solution is not amenable to classical mathematical solution techniques. With the advent of high performance computers, a new technology, termed computational simulation or, more generally, scientific simulation, that is based upon solving these complicated equations on the computer, has emerged. The basic concepts involved in simulating airflow are straightforward. Approximations to the unknowns in the equations that govern airflow are made that transforms the few highly complicated equations into millions of simple equations. The computer is then used to solve these equations using an algorithmic approach. In reality, the region around an aircraft is subdivided into small elements and within each element the flow variables are approximated in some appropriate and consistent form. This process of subdividing the space is termed mesh generation. The algorithms that solve the equations and in turn produce the unknown flow variables (such as pressure, density etc) are called the solution algorithms and these are structured to ensure that maximum efficiency can be obtained from high performance computers that will, in general, have many processors. The results of the calculations are then processed using computer graphics and important quantitative data such as lift and drag can be extracted.This technology is now used routinely in all major aerospace companies. Whilst not making the use of the wind tunnel redundant, the technology has enabled designers to explore new and innovative designs and ensure that fewer geometries need to be subjected to costly wind tunnel analysis.Whilst the basic concepts of computer simulation for high speed flows are simple, the requirement to predict accurately key aerodynamic parameters represents a significant technical and intellectual challenge. Representing the geometry of an aircraft accurately demands innovative ways of representing three-dimensional surfaces and the generation of the elements around the aircraft that will enable the solution algorithm to capture all the complex physics still remains a challenge. Whilst the equations of fluid flow can be written exactly, the restrictions in available computing power, even taking into account the capabilities of the World's largest computers, require researchers to make approximations, as is the case for the simulation of turbulent flow. For some cases, these approximations do not enable the details of the flow to be captured and hence the predictions do not accurately represent reality. This project is aimed at focusing on further technical developments that will increase the accuracy of high speed flows for complicated aerodynamic shapes, such as complete aircraft configurations, whilst ensuring that the computations can be performed in a time scale that meets real-world project deadlines encountered in design. In particular, the project will focus on enhancing our capability to predict aerodynamic parameters accurately, such as lift and drag, and to simulate highly complicated flowfields generated when an aircraft is in take-off and landing configuration where ground effects can be significant. When these developments have been completed, computer predictions will be compared with real test data to ensure appropriate validation of the techniques.

航空航天飞行器的传统设计涉及广泛使用风洞来测试不同的配置并最终确定设计。然而，这是一个昂贵且漫长的过程，还需要使用为特定流速设计的专业测试设施。随着计算机的出现，在过去的20年里出现了一种新技术，它为空气动力学设计提供了强有力的工具。控制空气运动的方程式几个世纪前就已为人所知。然而，对于一般的流动，他们的解决方案是不服从经典的数学解决方案的技术。随着高性能计算机的出现，出现了一种新的技术，称为计算模拟或更一般地称为科学模拟，其基于在计算机上求解这些复杂的方程。模拟气流所涉及的基本概念很简单。对控制气流的方程中的未知数进行近似，将少数高度复杂的方程转化为数百万个简单方程。然后，计算机使用算法方法来求解这些方程。实际上，飞机周围的区域被细分成小的单元，在每个单元内，流动变量以某种适当的和一致的形式近似。这个细分空间的过程称为网格生成。求解方程并进而产生未知流量变量（如压力、密度等）的算法称为求解算法，这些算法的结构是为了确保可以从通常具有许多处理器的高性能计算机中获得最大效率。计算结果再用计算机图形进行处理，提取出升力和阻力等重要的定量数据，这项技术现在已在所有主要的航空航天公司得到常规应用。虽然没有使用风洞多余的，该技术使设计人员能够探索新的和创新的设计，并确保更少的几何形状需要进行昂贵的风洞分析。虽然计算机模拟高速流的基本概念很简单，但准确预测关键空气动力参数的要求是一个重大的技术和智力挑战。准确地表示飞机的几何形状需要表示三维表面的创新方法，并且飞机周围的元素的生成将使解决方案算法能够捕获所有复杂的物理仍然是一个挑战。虽然流体流动的方程可以精确地写出，但可用计算能力的限制，即使考虑到世界上最大的计算机的能力，也需要研究人员进行近似计算，就像湍流模拟一样。在某些情况下，这些近似值不能捕获流的细节，因此预测不能准确地表示现实。该项目的目的是专注于进一步的技术发展，这将提高复杂气动外形（如完整的飞机构型）的高速流的准确性，同时确保计算可以在满足设计中遇到的实际项目期限的时间尺度内进行。特别是，该项目将侧重于提高我们的能力，以准确地预测气动参数，如升力和阻力，并模拟高度复杂的流场时，飞机在起飞和着陆配置，地面效应可能是显着的。当这些开发工作完成后，将把计算机预测与真实的试验数据进行比较，以确保这些技术得到适当的验证。