Laser Doppler Measurements of Twin Impinging Jets Aligned with a Crossflow  

作　　者：Jorge M.M. Barata Pedro S.D. Carvalho Femando M.S.P. Neves1, Andr6 R.R. Silva1, Diana F.C. VieiraI andDiamantino F.G. Duro Andre R.R. Silva Diana F.C. Vieira Diamantino F.G. Durao 

机构地区：[1]Departmentof Aerospace Sciences, University of Beira Interior, Covilha 6200-001, Portugal [2]Instituto Lusiada de Investigacao e Desenvolvimento, Universidade Lusiada, Lisbon 1349-001, Portugal

出　　处：《Journal of Physical Science and Application》2014年第7期403-411,共9页物理科学与应用（英文版）

摘　　要：This paper presents a detailed analysis of the complex flow beneath two impinging jets aligned with a low-velocity crossflow which is relevant for the future F-35 VSTOL configuration, and provides a quantitative picture of the main features of interest for impingement type of flows. The experiments were carried out for a Reynolds number based on the jet exit conditions of Rej = 4.3 × 10^4, an impingement height of 20.1 jet diameters and for a velocity ratio between the jet exit and the crossflow VR = V/Uo of 22.5. The rear jet is located at S = 6 D downstream of the first jet. The results show a large penetration of the first （upstream）jet that is deflected by the crossflow and impinges on the ground, giving rise to a ground vortex due to the collision of the radial wall and the crossflow that wraps around the impinging point like a scarf. The rear jet （located downstream） it is not so affected by the crossflow in terms of deflection, but due to the downstream wall jet that flows radially from the impinging point of the first jet it does not reach the ground. The results indicate a new flow pattern not yet reported so far, that for a VSTOL aircraft operating in ground vicinity with front wind or small forward movement may result in enhanced under pressures in the aft part of the aircraft causing a suction down force and a change of the pitching moment towards the ground.

关 键 词：VSTOL ground vortex TURBULENCE complex flows. 

分 类 号：O358[理学—流体力学] TN241[理学—力学]