在设计出口大于进口面积的斜流集管时，一个重要的考虑因素是确保集管下游的装置不会出现严重的流量分配不均。通过集管通道的扩散增加了流动分离的可能性，这是此类装置中不均匀分布的主要原因。这种不均匀分布是不可取的，因为它通常会导致斜集管下游流动部件的压降过大。本研究的目的是设计一个斜流集管，无明显分离，并尽可能实现最大扩散（即出入口面积比）。 这种集管，也称为弯曲扩散器，将沿着固体壁在任何地方都处于分离边缘，同时也将提供最大的静压上升。本文阐述了在几何约束条件下，确定提供最大静压升的集管外形的问题。假设不可压缩层流通过集管，由稳态Navier-Stokes方程控制。通过获得Navier-Stokes方程的数值解，可以解决在已知几何形状的集管中确定这种流动的问题。为了推断将导致更高压力升高的集管外形变化的方向和相对大小，假设沿集管壁的剪切应力必须接近，但略高于零。 移动收割台的壁，以沿壁获得预先指定的目标剪切应力。通过反复使用该程序，可获得最佳轮廓。开发了一个三维稳态Navier-Stokes解算器，该解算器使用有限体积公式和人工压缩性方法，用于该算法。Navier-Stokes解算器通过获得90度方截面弯管的数值结果来验证其精度，文献中提供了该几何形状的实验数据。然后在几个雷诺数下计算最佳扩散弯管。关键词:优化，设计，集管，流体流动，压降，几何形状，扩散器，流线流动，雷诺数，算法，稳态，计算。 引文:研讨会，ASHRAE交易，第97卷，Pt。1991年，纽约

An important consideration in the design of oblique flow headers whose exit is larger than the inlet area is to ensure that the devices downstream of the header do not experience a severely maldistributed flow. Diffusion through the header passage raises the possibility of flow separation, a primary cause of maldistribution in such devices. Such maldistribution is undesirable because it usually results in excessive pressure drops through flow components down-stream of the oblique header. The objective of the present study is to design an oblique flow header, free of gross separation, with the maximum diffusion (i.e., exit to entrance area ratio) possible. Such a header, also called a curved diffuser, will be on the verge of separation everywhere along the solid wall and at the same time will provide the maximum static pressure rise as well. The problem of determining the profile of a header that provides the maximum static pressure rise subject to some geometrical constraints is formulated. Incompressible, laminar flow governed by the steady-state Navier-Stokes equations is assumed through the header. The problem of determining such a flow in a header of known geometry can be solved by obtaining the numerical solution to the Navier-Stokes equations. To deduce the direction and relative magnitude of the change in header profile that will lead to a higher pressure rise, it is assumed that shear stress along the walls of the header must be close to, but slightly above zero. The walls of the header are moved to achieve a prespecified target shear stress along the walls. By repeated use of this procedure, optimum profiles are obtained. A three-dimensional, steady-state Navier-Stokes solver using a finite-volume formulation and artificial compressibility method has been developed for use with this algorithm. The Navier-Stokes solver is verified for accuracy by obtaining numerical results for flow through a 90 degree bend with a square cross section, a geometry for which experimental data are available in the literature. Optimum diffusing bends are then computed at several Reynolds numbers.KEYWORDS: optimum, designing, headers, fluid flow, pressure drop, geometry, diffusers, streamline flow, Reynolds numbers, algorithms, steady state, calculating.