Effects of Nozzle Pressure Ratio and Nozzle-to-Plate Distance to Flowfield Characteristics of an Under-Expanded Jet Impinging on a Flat Surface

Autor: Duy Thien Nguyen, Blake Maher, Yassin Hassan
Jazyk: angličtina
Rok vydání: 2019
Předmět:
Zdroj: Aerospace, Vol 6, Iss 1, p 4 (2019)
Druh dokumentu: article
ISSN: 2226-4310
DOI: 10.3390/aerospace6010004
Popis: The current work experimentally investigates the flowfield characteristics of anunder-expanded turbulent jet impinging on a solid surface for various nozzle-to-plate distances2.46Dj, 1.64Dj, and 0.82Dj (Dj is the jet hydraulic diameter), and nozzle pressure ratios (NPRs)ranging from 2 to 2.77. Planar particle image velocimetry (PIV) measurements were performedin the central plane of the test nozzle and near the impingement surface. From the obtained PIVvelocity vector fields, flow characteristics of under-expanded impinging jets, such as mean velocity,root-mean-square fluctuating velocity, and Reynolds stress profiles, were computed. Comparisonsof statistical profiles obtained from PIV velocity measurements were performed to study the effectsof the impingement surface, nozzle-to-plate distances, and NPRs to the flow patterns. Finally,proper orthogonal decomposition (POD) analysis was applied to the velocity snapshots to reveal thestatistically dominant flow structures in the impinging jet regions.
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