Three-dimensional vortex dynamics and convective heat transfer in circular and chevron impinging jets |
| |
| Affiliation: | 1. Aerospace Engineering Department, Delft University of Technology, Kluyverweg 2, 2629 HS, Delft, The Netherlands;2. Dipartimento di Ingegneria Aerospaziale (DIAS), University of Naples “Federico II”, Via Claudio 21, 80125 Naples, Italy;1. Department of Mechanical Engineering, Tokyo University of Science, 6-3-1 Niijuku, Katsushika-ku, Tokyo 125-8585, Japan;2. Research Institute for Science & Technology, Tokyo University of Science, 6-3-1 Niijuku, Katsushika-ku, Tokyo 125-8585, Japan;1. College of Energy and Power Engineering, Nanjing University of Aeronautics and Astronautics, Nanjing 210016, China;2. School of Energy and Mechanical Engineering, Nanjing Normal University, Nanjing 210042, China;3. Jiangsu Province Key Laboratory of Aerospace Power System, Nanjing University of Aeronautics and Astronautics, Nanjing 210016, China;4. Collaborative Innovation Center of Advanced Aero-Engine, Beijing 100191, China;1. Department of Industrial Engineering, Aerospace Section, Università degli Studi di Napoli Federico II, 80125 via Claudio 21, Napoli, Italy;2. Aerospace Engineering Group, Universidad Carlos III de Madrid, 28911 Av. de la Universidad 30, Leganés, Spain;1. Turbulence, Mixing and Flow Control Group, Department of Aeronautics, Imperial College London, London SW7 2AZ, United Kingdom;2. Institute PPRIME, Department of Fluid Flow, Heat Transfer and Combustion, CNRS – Université de Poitiers ENSMA, Téléport 2, Boulevard Marie et Pierre Curie, BP 30179, 86962 Futuroscope Chasseneuil Cedex, France;1. Fluid Mechanics Group, E.T.S. Ingeniería Industrial, Universidad de Málaga, C/Dr. Ortiz Ramos s/n, 29071 Málaga, Spain;2. School of Computing and Mathematical Sciences, University of Greenwich, Old Royal Naval College, Park Row, London SE10 9LS, UK |
| |
| Abstract: | This paper describes an experimental investigation at Reynolds number equal to 5000 on circular and chevron impinging jets by means of time-resolved tomographic particle image velocimetry (TR-TOMO PIV) and infrared (IR) thermography. TR-TOMO PIV experiments are performed at kilo-hertz repetition rate in a tailored water jet facility where a plate is placed at a distance of 4 diameters from the nozzle exit. Using air as working fluid, time-averaged convective heat transfer is measured on the impinged plate by means of IR thermography with the heated-thin-foil heat transfer sensor for nozzle-to-plate distances ranging from 2 to 10 diameters. The circular impingement shows the shedding and pairing of axisymmetric toroidal vortices with the later growth of azimuthal instabilities and counter-rotating streamwise vortices. In the chevron case, instead, the azimuthal coherence is replaced by counter-rotating pairs of streamwise vortices that develop from the chevron notches. The heat transfer performances of the chevron impingement are compared with those of the circular one, analyzing the influence of the nozzle-to-plate distance on the distribution of Nusselt number. The chevron configuration leads to enhanced heat transfer performances for all the nozzle-to-plate distances hereby investigated with improvements up to 44% at the center of the impinged area for nozzle-to-plate distance of 4. Such enhancements are discussed in relation to the streamwise structures that, compared with the toroidal vortices, are associated with an earlier penetration of turbulence towards the jet axis and a higher arrival speed. |
| |
| Keywords: | |
| 本文献已被 ScienceDirect 等数据库收录！ |
|
