Fan Aerodynamics With a Short Intake at High Angle of Attack
Fan Aerodynamics With a Short Intake at High Angle of Attack
复制标题
高迎角短进气的风扇空气动力学
DOI：
10.1115/gt2020-16296
复制
发表时间：
2020
期刊：
影响因子：
--
通讯作者：
M. Wilson
中科院分区：
文献类型：
--
作者：
B. Mohankumar;C. Hall;M. Wilson
设计用于在大迎角 (AOA) 飞行条件下保持推力的风扇可以利用较短进气设计的巡航燃油燃烧优势。本文考虑如何设计风扇转子径向压力比分布和叶尖速度三角形，以在与高迎角运行的短进气耦合时提高推力。使用非稳态计算流体动力学研究两个 AOA 值：20 度（附着流）和 35 度（分离流）。高迎角时的推力由三个关键损失和功输入机制控制。 (i) 转子阻塞损失：气流在进气底唇周围加速并以高马赫数进入转子。与中高设计相比，采用叶尖高径向压力比分布设计的风扇可通过分离式进气口减少阻塞损失，特别是当叶尖速度三角形设计为高扩散而不是高弯度时。 (ii) 转子-分离相互作用损失：转子在分离内部运行时吸入低质量流量，并且外壳边界层分离。高扩散尖端设计加强了套管分离，但这种损失并没有超过改善的阻塞损失。 (iii) 径向流中的功输入：高迎角会产生通过转子的强径向流，这会改变作用在流上的功量和方式。采用中高径向压力比分布设计的风扇为向轮毂迁移的流线提供了很高的工作量。综合这些发现，我们提出了两种提高高迎角推力的设计理念：高功（中高径向压力比分布）或低损耗（具有高扩散尖端速度三角形的叶尖-高径向压力比分布）。
Fans that are designed to maintain thrust at the high angle of attack (AOA) flight condition could exploit the cruise fuel burn benefit of a shorter intake design. This article considers how the fan rotor radial pressure ratio distribution and tip velocity triangle can be designed to improve thrust when coupled to a short intake operating at high AOA. Two AOA values are investigated using unsteady computational fluid dynamics: 20 deg (attached flow) and 35 deg (separated flow). Thrust at high AOA is governed by three key loss and work input mechanisms. (i) Rotor choking loss: flow is accelerated around the intake bottom lip and enters the rotor with high Mach numbers. Fans designed with a tip-high radial pressure ratio distribution reduced choking loss with a separated intake compared to a mid-high design, particularly when the tip velocity triangle was designed with high diffusion instead of high camber. (ii) Rotor–separation interaction loss: the rotor ingests low mass flow when operating inside the separation and the casing boundary layer separates. High diffusion tip designs strengthened the casing separation, but this penalty did not outweigh improved choking loss. (iii) Work input in radial flows: high AOA generates strong radial flows through the rotor, which alter both the amount and the way work is imparted on the flow. Fans designed with a mid-high radial pressure ratio distribution imparted high work on streamlines migrating toward the hub. Consolidating these findings, we propose two design philosophies for improved thrust at high AOA: high work (mid-high radial pressure ratio distribution) or low loss (tip-high radial pressure ratio distribution with high diffusion tip velocity triangle).
DOI：
10.1115/gt2015-43025
发表时间：
2015-06
期刊：
Journal of Turbomachinery
影响因子：
--
作者：
D. Perović;C. Hall;E. Gunn
通讯作者：
D. Perović;C. Hall;E. Gunn