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Selective enhancement of oblique waves caused by finite amplitude second mode in Supersonic boundary layer

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Applied Mathematics and Mechanics(English Edition) 2017年第8期38卷 1109-1126页

作者： Cunbo ZHANG Jisheng LUO Department of Mechanics Tianjin UniversityTianjin 300072China

Nonlinear interactions of the two-dimensional （2D） second mode with oblique modes are studied numerically in a Mach 6.0 fiat-plate boundary layer, focusing on its selective enhancement effect on amplification of different oblique waves. Evolution of oblique modes with various frequencies and spanwise wavenumbers in the presence of 2D second mode is simulated successively, using a modified parabolized stability equation （PSE） method, which is able to simulate interaction of two modes with different frequen- cies efficiently. Numerical results show that oblique modes in a broad band of frequencies and spanwise wavenumbers can be enhanced by the finite amplitude 2D second mode instability wave. The enhancement effect is accomplished by interaction of the 2D second mode, the oblique mode, and a forced mode with difference frequency. Two types of oblique modes are found to be more amplified, i.e., oblique modes with frequency close to that of the 2D second mode and low-frequency first mode oblique waves. Each of them may correspond to one type of transition routes found in transition experiments. The spanwise wavenumber of the oblique wave preferred by the nonlinear interaction is also determined by numerical simulations.

关键词： Supersonic boundary layer boundary layer instability nonlinear mode interaction

NUMERICAL STUDY FOR RESONANT TRIAD INTERACTION AND SECONDARY INSTABILITY IN TWO-DIMENSIONAL Supersonic boundary layer

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Applied Mathematics and Mechanics(English Edition) 2006年第2期27卷 141-148页

作者：董亚妮周恒 Department of MechanicsTianjin University Tianjin 300072P.R.China Liuhui Center of Applied Mathematics Nankai University and Tianjin UniversityTianjin 300072P.R.China (Contributed by ZHOU Heng)

By direct numerical simulation, a Supersonic boundary layer was studied to see whether the mechanism for the generation of sub-harmonic waves, similar to those for the incompressible flows, existed in the process of laminar-turbulent transition. The results showed that mechanisms of both resonant triad and secondary instability did exist. Discussions were made on whether these two mechanisms are really important in laminarturbulent transition.

关键词： resonant triad secondary instability Supersonic boundary layer T-S wave

STUDY OF MECHANISM OF BREAKDOWN IN LAMINARTURBULENT TRANSITION OF Supersonic boundary layer ON FLAT PLATE

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Applied Mathematics and Mechanics(English Edition) 2006年第4期27卷 425-434页

作者：曹伟黄章峰周恒 Department of Mechanics Tianjin University Tianjin 300072P. R. China Liuhui Center of Applied Mathematics Nankai University and Tianjin UniversityTianjin 300072P. R. China

Spatial mode direct numerical simulation has been applied to study the mechanism of breakdown in laminar-turbulent transition of a Supersonic boundary layer on a fiat plate with Mach number 4.5. Analysis of the result showed that, during the breakdown process in laminar-turbulent transition, the mechanism causing the mean flow profile to evolve swiftly from laminar to turbulent was that the modification of mean flow profile by the disturbance, when they became larger, leads to remarkable change of its stability characteristics. Though the most unstable T-S wave was of second mode for laminar flow, the first mode waves played the key role in the breakdown process in laminar-turbulent transition.

关键词： Supersonic boundary layer transition breakdown spatial mode

EVOLUTION OF A 2-D DISTURBANCE IN A Supersonic boundary layer AND THE GENERATION OF SHOCKLETS

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Applied Mathematics and Mechanics(English Edition) 2004年第1期25卷 1-9页

作者：黄章峰周恒 Department of Mechanics

Through direct numerical simulation,the evolution of a 2-D disturbance in a Supersonic boundary layer has been investigated.At a chosen location,a small amplitude T-S wave was fed into the boundary layer to investigate its evolution. Characteristics of non-linear evolution have been found. Two methods were applied for the detection of shocklets,and it was found that when the amplitude of the disturbance reached a certain value, shocklets would be generated, which should be taken into consideration when nonlinear theory of hydrodynamic stability for compressible flows is to be established.

关键词： Supersonic boundary layer evolution of disturbance shocklet

Experimental and numerical investigation of controlled disturbances development from two sources in Supersonic boundary layer

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Advances in Aerodynamics 2019年第1期1卷 288-300页

作者： G.L.Kolosov A.D.Kosinov A.N.Semenov A.A.Yatskikh Khristianovich Institute of Theoretical and Applied Mechanics SB RAS Novosibirsk 630090Russia

The paper presents the experimental results and the results of direct numerical simulation of the development and interaction of two wave trains from two point sources of controlled disturbances in a Supersonic boundary layer on a flat plate with an incident flow Mach number of 2.5.Sources were located parallel to the leading edge of the model.For the introduction of controlled disturbances into the boundary layer,the normal component of the mass flow rate was varied in the calculations.In the experiment,periodic glow discharges at a frequency of 20 kHz were used.In both cases,the disturbances sources worked synchronously.Mass flow rate pulsations were measured and recorded in sections,parallel to the leading edge of the model,near the maximum of disturbances along the boundary layer.In the experiment,a constanttemperature hot-wire anemometer was used.After performing a discrete Fourier transform,the spatial distributions of disturbances,the beta-spectra were determined,and the wave characteristics of the development of disturbances downstream were estimated.In addition,direct numerical simulation of the downstream development of disturbances from a single source was performed.The work presents a comparison of experimental and theoretical calculated data.The paper discusses the effects inherent in the interaction of unstable traveling controlled disturbances from two sources operating synchronously.

关键词： :DNS Computational modeling Supersonic boundary layer Compressibility Discharge Flat plate Hot-wire anemometer Instability Turbulence

Experimental Characterization of the supersonic Transitional Wake Downstream of a Single Roughness Element

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Journal of Thermal Science 2020年第4期29卷 1085-1093页

作者： BOTTINI Henny SARACOGLU Bayindir H. PANIAGUA Guillermo Department of Aerospace Engineering Nagoya UniversityNagoya 464-8603Japan Aeronautics and Aerospace Department von Karman Institute for Fluid DynamicsRhode-Saint-Genese B-1640Belgium Zucrow Laboratories Purdue University500 Allison RoadWest Lafayette 47907INUSA

An experimental campaign was carried out to investigate the characteristics of the transitional supersonic wake downstream of a single roughness element. Two Mach numbers were tested, 1.6 and 2.3, and two roughness heights, 0.1 mm and 1 mm. Unsteady and steady wall temperature measurements were taken along and across the roughness wake. The spatial trends of adiabatic wall temperature and heat flux, and the spectral time evolution of temperature were documented in this paper. The initial wall temperature was varied during the temperature measurements, and the resulting steady and unsteady effects on the roughness wake were investigated. The streamwise trends of heat-flux and adiabatic-wall temperature confirmed the transitional nature of the roughness wake. Spectral analysis showed that roughness height and initial wall temperature had the same type of effect on the wake wall-temperature fluctuations. The effect of roughness height was more sensible at Mach 2.3, and that of the initial wall temperature was more evident with the smallest roughness also tested at Mach 2.3.

关键词： Supersonic boundary layer roughness wake steady measurements unsteady measurements heat transfer