Application of Rainbow Schlieren Deflectometry for Jets from Round Laval Nozzles Followed by Cylindrical Ducts  

作　　者：Ryota Fukunaga Muhammad Minarul Islam Yusuke Awata Shinichiro Nakao Yoshiaki Miyazato Ryota Fukunaga;Muhammad Minarul Islam;Yusuke Awata;Shinichiro Nakao;Yoshiaki Miyazato(Department of Mechanical Systems Engineering, The University of Kitakyushu, Kitakyushu, Japan;Bangabandhu Sheikh Mujibur Rahman Science and Technology University, Gopalganj, Bangladesh;Subaru Corporation, Osawa, Mitaka-shi, Tokyo, Japan)

机构地区：[1]Department of Mechanical Systems Engineering, The University of Kitakyushu, Kitakyushu, Japan [2]Bangabandhu Sheikh Mujibur Rahman Science and Technology University, Gopalganj, Bangladesh [3]Subaru Corporation, Osawa, Mitaka-shi, Tokyo, Japan

出　　处：《Journal of Flow Control, Measurement & Visualization》2021年第2期15-27,共13页流量控制、测量及可视化（英文）

摘　　要：The jet from a round Laval nozzle followed by a cylindrical duct with an inner diameter of 10 mm and a length of 50 mm is investigated experimentally. The Laval nozzle has a design Mach number of 1.5. Quantitative flow visualization of the jet issued from the duct exit is performed over a range of nozzle pressure ratios from 2.0 to 4.5 using the rainbow schlieren deflectometry combined with the computed tomography to investigate the jet three-dimensional structure. The flow features of the near-field shock systems in the jets are displayed with the density contour plot at the cross-section including the jet centerline. Effects of the nozzle pressure ratio on the density profile along the jet centerline are clarified quantitatively. In addition, a comparison between the present experiment and the previous one with a conventional Laval nozzle for jet centerline density profiles is carried out to examine the effect of the cylindrical duct. Furthermore, the three-dimensional structures of overexpanded and underexpanded jets are demonstrated with the isopycnic surfaces to visualize the internal flow features.The jet from a round Laval nozzle followed by a cylindrical duct with an inner diameter of 10 mm and a length of 50 mm is investigated experimentally. The Laval nozzle has a design Mach number of 1.5. Quantitative flow visualization of the jet issued from the duct exit is performed over a range of nozzle pressure ratios from 2.0 to 4.5 using the rainbow schlieren deflectometry combined with the computed tomography to investigate the jet three-dimensional structure. The flow features of the near-field shock systems in the jets are displayed with the density contour plot at the cross-section including the jet centerline. Effects of the nozzle pressure ratio on the density profile along the jet centerline are clarified quantitatively. In addition, a comparison between the present experiment and the previous one with a conventional Laval nozzle for jet centerline density profiles is carried out to examine the effect of the cylindrical duct. Furthermore, the three-dimensional structures of overexpanded and underexpanded jets are demonstrated with the isopycnic surfaces to visualize the internal flow features.

关 键 词：Rainbow Schlieren Deflectometry Jet Flow Shock Wave Computed Tomography 

分 类 号：O35[理学—流体力学]