Journal ArticleDOI
Overexpansion Effects on Characteristics of Mach Waves from a Supersonic Cold Jet
Taku Nonomura,Kozo Fujii +1 more
TLDR
In this article, an implicit large eddy simulation of a Mach 2.0 supersonic free jet is computed for code validation, and the results show qualitatively good agreement with the experiments.Abstract:
For predicting acoustic waves emitted from a rocket plume, the overexpansion effects on Mach 3.0 supersonic jet acoustics are investigated using an implicit large eddy simulation. A Mach 2.0 supersonic free jet is computed for code validation, and the results show qualitatively good agreement with the experiments. Then, computations of three different jets (design Mach numbers 3.0, 3.5, and 4.0 with fully expanded jet Mach number 3.0) are conducted, and nondimensionalizations based on design parameters and fully expanded parameters are discussed. Acoustic far-field spectra show that nondimensionalization based on fully expanded parameters works well for the high-Mach-number overexpanded jets, as it does for the low-Mach-number underexpanded jets that were investigated in previous studies. This nondimensionalization improves the accuracy of prediction of the acoustic waves emitted from rocket plumes because one parameter, the design Mach number, can be neglected for acoustic far fields. In addition, actual overexpansion effects after nondimensionalization are discussed. A comparison of the near flowfields and acoustic fields shows that Mach wave sources move upstream because of the existence of Mach disks, which enhances shear-layer mixing. Meanwhile, the overexpanded jet, which possesses only a shock cell without Mach disks, exhibits the same Mach wave generation characteristics as an ideally expanded jet.read more
Citations
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New insights into large eddy simulation
TL;DR: In this paper, the authors proposed a monotone integrated large eddy simulation approach, which incorporates a form of turbulence modeling applicable when the large-scale flows of interest are intrinsically time dependent, thus throwing common statistical models into question.
Journal ArticleDOI
On the feedback mechanism in supersonic cavity flows
TL;DR: In this article, self-sustained oscillations in supersonic cavity flows are investigated by implicit large-eddy simulations of a flow past a three-dimensional rectangular cavity with length-to-depth ratio of 2.
Journal ArticleDOI
A Numerical Scheme Based on an Immersed Boundary Method for Compressible Turbulent Flows with Shocks: Application to Two-Dimensional Flows around Cylinders
TL;DR: A computational code adopting immersed boundary methods for compressible gas-particle multiphase turbulent flows is developed and validated through two-dimensional numerical experiments, and the present scheme is successfully applied to moving two-cylinder problems.
Journal ArticleDOI
Study on Acoustic Prediction and Reduction of Epsilon Launch Vehicle at Liftoff
TL;DR: In this article, the acoustic level of the Epsilon launch vehicle at liftoff was investigated using a 1/42-scale model test and a numerical analysis, and it was revealed from the numerical analysis that the reflection of Mach waves radiating from the free jet within the flame path is the dominant acoustic source.
Journal ArticleDOI
High-speed jet noise
Christophe Bailly,Kozo Fujii +1 more
TL;DR: In this paper, a comprehensive review of high-speed jet noise is provided, including mixing noise, Mach wave radiation, broadband shockcell noise, and screech tones, examining the physics involved, and introducing recent numerical and experimental developments.
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