2023 Fiscal Year Final Research Report

Three-dimensional unsteady visualization of jet noise generation process using synchronous fluid-acoutic visualization

Research Project

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Project/Area Number	21H01529
Research Category	Grant-in-Aid for Scientific Research (B)
Allocation Type	Single-year Grants
Section	一般
Review Section	Basic Section 24010:Aerospace engineering-related
Research Institution	The University of Tokyo
Principal Investigator	Susumu Teramoto 東京大学, 大学院工学系研究科(工学部), 教授 (30300700)
Co-Investigator(Kenkyū-buntansha)	岡本光司東京大学, 大学院新領域創成科学研究科, 准教授 (70376507)
Project Period (FY)	2021-04-01 – 2024-03-31
Keywords	超音速ジェット / ジェット騒音 / 可視化 / BOS法 / Computed Tomography
Outline of Final Research Achievements	To visually clarify the noise generation mechanism of jet noise from supersonic turbulent jets, the three-dimensional structures of both the coherent structure of the turbulent jet shear layer and the near-field sound wave have been successfully visualized. These two phenomena are difficult to visualize with conventional experimental methods due to their high frequency and intermittency. From the visualization, the correlation between the coherent structure and the far-field sound, as well as the correlation between the near-field sound wave and the circumferential correlation of far-field noise, has been clarified. The HB-LES method, which can efficiently extract periodic components from unsteady turbulent flow fields, has been proposed. This method has been applied to various flow fields, from canonical flows to unsteady turbulent flows including shock waves. It was confirmed that the method has accuracy comparable to existing methods while greatly improving efficiency.
Free Research Field	流体力学
Academic Significance and Societal Importance of the Research Achievements	実験面では、高周波数かつ間欠的であるため、従来は大規模で高価な計測系が必要だった音源の流れ構造や近傍場の三次元構造と遠方場音の関係を、比較的簡便な計測装置で計測することに成功した。シミュレーション面でも、非定常乱流のシミュレーションについて、従来と同等の精度を保ちつつ、計算速度をストローハル数倍程度向上させることに成功した。これらの成果により、本研究で取り組んだジェット騒音よりも複雑な、より実用的な高速流の乱流騒音の研究が進展することが期待できる。