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Experimental and numerical investigation on the effect of boundary layer injection on skin friction in a scramjet combustor

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Aerospace science and technology 2025年 163卷

作者： Qu, Zhenming Li, Xinke Chen, Wenjuan Luo, Feiteng Wei, Baoxi Yang, Fujiang Nan, Nan School of Aerospace Engineering Huazhong University of Science and Technology Wuhan430074 China Science and Technology of Scramjet Laboratory Beijing Power Machinery Research Institute Beijing100074 China

This study experimentally and numerically investigates wall drag reduction via boundary layer injection in a scramjet combustor model using a micro-step injection configuration. Experimental results demonstrate that wall friction initially decreases with increasing injection mass flow ratio within the shock reflection zone induced by the jet, followed by a detrimental effect beyond a critical threshold. Schlieren visualization and pressure measurements reveal intensified shock-boundary layer interactions (SBLI) and thickened boundary layers under higher injection ratios. Three-dimensional simulations elucidate the underlying flow mechanisms: boundary layer injection reduces the viscous dissipation contribution (Cf,V) to wall friction while amplifying TKE production(Cf,T) effects. Notably, the integrand spatial development term (Cf,G) exhibits a negative contribution (drag-reducing) at low injection ratios—contrary to its positive role in baseline flows. This is because that the wall-normal convection term Cf,C shifts from positive (drag-enhancing) to negative (drag-reducing) contributions under low injection ratios due to modified velocity profiles. This beneficial effect diminishes at higher mass flow ratios as near-wall laminarization thickens the viscous sublayer, amplifying the streamwise development term (Cf,D) dominance over the suppressed convective effects. Analysis suggests an optimal injection mass flow ratio exists for maximal drag reduction, validated through empirical modeling and iterative experiments. The findings provide a mechanistic framework for tailoring boundary layer injection strategies, with implications for extending predictive models to streamwise-varying injection designs in high-speed propulsion systems. © 2025 Elsevier Masson SAS

关键词： Surveying

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Experimental characteristics of a two-electrode plasma synthetic jet actuator array in serial

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Chinese Journal of Aeronautics 2018年第12期31卷 2234-2247页

作者： Yan ZHOU Zhixun XIA Zhenbing LUO Lin WANG Xiong DENG Science and Technology on Scramjet Laboratory National University of Defense Technology

Plasma Synthetic Jet(PSJ) actuators have shown wide and promising application prospects in high-speed flow control, due to their advantages including high exhaust speed, wide frequency band, rapid response, and non-moving components. Although previous studies on PSJ actuators are abundant, most of them have focused on the performance of a single actuator. However, in practice, an actuator array is very necessary for large-scale aerodynamic actuation on account of the small affected area of a single PSJ. In this paper, the characteristics of a twoelectrode plasma synthetic jet actuator array in serial are investigated experimentally. Compared to a parallel actuator array, the serial actuator array requires simpler power supply design and is much easier to realize. High-speed photography of the discharge evolution, voltage-current measurement, and shadowgraphy visualization are used in the investigation. Experimental results show that, for the serial actuator array, weak discharges happen firstly between energized and suspending electrodes, and then a strong pulse arc discharge is triggered. The breakdown voltage in serial is irrelevant to such factors as the number of actuators, the maximum or minimum gap in serial,the connection sequence, etc. It is mainly determined by the sum of gaps. For serial actuators with the same anode-to-cathode spacing, the energy deposition is the same, and the jet is synchronous and similar. Because of the entrainment and merging of adjacent jet vortices, the jet front speed of an aligned synchronous jet array increases as the orifice distance decreases. To achieve the highest jet front velocity, the orifice of the actuator has an optimal diameter.

关键词： Capacitive power supply Flow control Plasma synthetic jet Pulse arc discharge Serial actuator array Two-electrode

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A new surface catalytic model for silica-based thermal protection material for hypersonic vehicles

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Chinese Journal of Aeronautics 2015年第5期28卷 1355-1361页

作者： Li Kai Liu Jun Liu Weiqiang Science and Technology on Scramjet Laboratory National University of Defense Technology

Silica-based materials are widely employed in the thermal protection system for hypersonic vehicles, and the investigation of their catalytic characteristics is crucially important for accurate aerothermal heating prediction. By analyzing the disadvantages of Norman＇s high and low temperature models, this paper combines the two models and proposes an eight-reaction combined surface catalytic model to describe the catalysis between oxygen and silica surface. Given proper evaluation of the parameters according to many references, the recombination coefficient obtained shows good agreement with experimental data. The catalytic mechanisms between oxygen and silica surface are then analyzed. Results show that with the increase of the wall temperature, the dominant reaction contributing to catalytic coefficient varies from Langmuir Hinshelwood （LH） recombination （Tw 〈 620 K） to Eley Rideal （ER） replacement （620 K 〈 Tw 〈 1350 K）, and then to 02 desorption （Tw 〉 1350 K）. The surface coverage of chemisorption areas varies evidently with the dominant reactions in the high temperature （HT） range, while the surface coverage of physisorption areas varies within quite low temperature （LT） range （Tw 〈 250 K）. Recommended evaluation of partial parameters is also given.

关键词： Aerothermal heating Catalytic efficiency Hypersonic vehicle Silica-based material Surface catalytic Thermal protection system

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Design of a continuously variable Mach-number nozzle

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Journal of Central South University 2015年第2期22卷 522-528页

作者：郭善广王振国赵玉新 Science and Technology on Scramjet Laboratory National University of Defense Technology

A design method was developed to specify the profile of the continuously variable Mach-number nozzle for the supersonic wind tunnel. The controllable contour design technique was applied to obtaining the original nozzle profile, while other Machnumbers were derived from the transformation of the original profile. A design scheme, covering a Mach-number range of3.0

关键词： wind tunnel variable Mach-number nozzle flow quality method of characteristics numerical validation

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Progress in research on mixing techniques for transverse injection flow fields in supersonic crossflows

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Journal of Zhejiang University-science A(Applied Physics & Engineering) 2013年第8期14卷 554-564页

作者： Wei HUANG Li YAN Science and Technology on Scramjet Laboratory National University of Defense Technology

The transverse injection flow field has an important impact on the flowpath design of scramjet engines. At present a combination of the transverse injection scheme and any other flame holder has been widely employed in hypersonic propulsion systems to promote the mixing process between the fuel and the supersonic freestream; combustion efficiency has been improved thereby, as well as engine thrust. Research on mixing techniques for the transverse injection flow field is summarized from four aspects, namely the jet-to-crossflow pressure ratio, the geometric configuration of the injection port, the number of injection ports, and the injection angle. In conclusion, urgent investigations of mixing techniques of the transverse injection flow field are pro- posed, especiaUy data mining in the quantitative analytical results for transverse injection flow field, based on results from multi-objective design optimization theory.

关键词： Aerospace propulsion system Transverse injection Mixing Supersonic crossflow

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Performance comparison between waverider and wide-speed-range gliding vehicle based on CFD approaches

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science China(Technological sciences) 2019年第10期62卷 1861-1870页

作者： ZHANG TianTian WANG ZhenGuo HUANG Wei YAN XiaoTing Science and Technology on Scramjet Laboratory National University of Defense Technology

Wide-speed-range gliding vehicle(WSRGV) is designed to adapt to the variable cruising environment that hypersonic vehicles will encounter during the mission implementation. Based on the cone-derived theory, a novel design technique of WSRGV has been developed. Theoretically, the functional relationship between cone-derived waverider’s volumetric efficiency and its design Mach number can be built through sampling approach as long as the geometries of design conical shock wave and the upper base curve are fixed. Based on the functional relationship, a cone-derived waverider that owns the same volumetric efficiency with a giving WSRGV can be acquired. This paper compared the aerodynamic performance between WSRGV and the cone-derived waverider sharing the same volumetric efficiency in a wide Mach number range. Their aerodynamic properties versus angle of attack have also been compared under the waverider’s design Mach number. The obtained result shows that WSRGV shares similar aerodynamic performance with the cone-derived waverider with the same volumetric efficiency. The aero-surfaces in the margin area of this kind of configuration have a larger contribution to the lift-to-drag ratio in comparison with the aero-surfaces in the central area. The configuration with a thick central body and thin margin place owns not only better aerodynamic performance but also better loading property.

关键词： wide-speed range cone-derived waverider volumetric efficiency lift-to-drag ratio loading property

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Numerical investigation on properties of attack angle for an opposing jet thermal protection system

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Chinese Physics B 2012年第8期21卷 289-294页

作者：陆海波刘伟强 Science and Technology on Scramjet Laboratory National University of Defense Technology

The three-dimensional Navier Stokes equation and the k-ε viscous model are used to simulate the attack angle characteristics of a hemisphere nose-tip with an opposing jet thermal protection system in supersonic flow conditions. The numerical method is validated by the relevant experiment. The flow field parameters, aerodynamic forces, and surface heat flux distributions for attack angles of 0°, 2°, 5°, 7°, and 10° are obtained. The detailed numerical results show that the cruise attack angle has a great influence on the flow field parameters, aerodynamic force, and surface heat flux distribution of the supersonic vehicle nose-tip with an opposing jet thermal protection system. When the attack angle reaches 10°, the heat flux on the windward generatrix is close to the maximal heat flux on the wall surface of the nose-tip without thermal protection system, thus the thermal protection has failed.

关键词： properties of attack angle opposing jet thermal protection system supersonic vehicle,computer simulation

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High-temperature gas effects on aerodynamic characteristics of waverider

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Chinese Journal of Aeronautics 2015年第1期28卷 57-65页

作者： Liu Jun Li Kai Liu Weiqiang Science and Technology on Scramjet Laboratory National University of Defense Technology

This paper focuses on the analysis of high-temperature effect on a conical waverider and it is a typical configuration of near space vehicles. Two different gas models are used in the numerical simulations, namely the thermochemical non-equilibrium and perfect gas models. The non-equilibrium flow simulations are conducted with the usage of the parallel non-equilibrium program developed by the authors while the perfect gas flow simulations are carried out with the commercial software Fluent. The non-equilibrium code is validated with experimental results and grid sensitivity analysis is performed as well. Then, numerical simulations of the flow around the conical waverider with the two gas models are conducted. In the results, differences in the flow structures as well as aerodynamic performances of the conical waverider are compared. It is found that the thermochemical non-equilibrium effect is significant mainly near the windward boundary layer at the tail of the waverider, and the non-equilibrium influence makes the pressure center move forward to about 0.57% of the whole craft＇s length at the altitude of 60 km.

关键词： perfect aerodynamic craft validated usage altitude symmetric length stand relaxation

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A novel optimal design for an application-oriented synthetic jet actuator

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Chinese Journal of Aeronautics 2014年第3期27卷 514-520页

作者： Deng Xiong Xia Zhixun Luo Zhenbing Wang Lin Science and Technology on Scramjet Laboratory National University of Defense Technology

The evaluation indicator for the performance of a synthetic jet actuator （SJA） is well-defined because of its various applications, which require optimal design to improve its performance and extend its field of application. This paper presents a novel approach to the optimal design of an SJA applied to enhance fuel/air mixture. It optimizes the combination of an actuator＇s geometric parameters by selecting the strength of vortex pairs as the evaluation indicator, coupled with orthogonal experiments and analysis of variance （AOV）. The results indicate that slot width is the most notable factor influencing the strength of vortex pairs, followed by cavity height and slot depth. The optimal value of the strength of vortex pairs increases by 32.5%over the experimental data of the base case, and more than 8.4%compared with the simulation results of the orthogonal experiments. It is concluded that the optimal method can effectively improve the performance of an SJA applied in mixing enhancement, reducing the test numbers and the associated design cycle and cost.

关键词： Analysis of variance Evaluation indicator Orthogonal experiment Strength of vortex pairs Synthetic jet

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Experimental investigations of detonation initiation by hot jets in supersonic premixed flows

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Chinese Physics B 2012年第12期21卷 305-309页

作者：韩旭周进林志勇 Science and Technology on Scramjet Laboratory National University of Defence Technology

A new method to initiate and sustain the detonation in supersonic flow is investigated. The reaction activity of coming flow may influence the result of detonation initiation. When a hot jet initiates a detonation wave successfully, there may exist two types of detonations. If the detonation velocity is greater than the velocity of coming flow, there will be a normal detonation here. Because of the influence of boundary layer separation, the upstream detonation velocity is much greater than the Chapman-Jouguet （C J） detonation velocity. On the other hand, if the detonation velocity is less than the velocity of coming flow, an oblique detonation wave （ODW） will form. The ODW needs a continuous hot jet to sustain itself. If the jet pressure is lower than a certain value, the ODW will decouple. In contrast, the normal detonation wave can sustain itself without the hot jet.

关键词： hot jet detonation supersonic flow

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