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Progress in helicopter infrared signature suppression

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Chinese Journal of Aeronautics 2014年第2期27卷 189-199页

作者： Zhang jingzhou Pan Chengxiong Shan Yong Jiangsu Province Key Laboratory of Aerospace Power System College of Energy & Power Engineering Nanjing University of Aeronautics and Astronautics

Due to their low-attitude and relatively low-speed fight profiles, helicopters are subjected to serious threats from radio, infrared （IR）, visual, and aural detection and tracking. Among these threats, infrared detection and tracking are regarded as more crucial for the survivability of helicop- ters. In order to meet the requirements of infrared stealth, several different types of infrared sup- pressor （IRS） for helicopters have been developed. This paper reviews contemporary developments in this discipline, with particular emphasis on infrared signature suppression, advances in mixer-ejectors and prediction for helicopters. In addition, several remaining challenges, such as advanced IRS, emissivity optimization technique, helicopter infrared characterization, etc., are proposed, as an initial guide and stimulation for future research. In the future, the comprehen- sive infrared suppression in the 3-5 μm and 8-14 μm bands will doubtfully become the emphasis of helicopter stealth. Multidisciplinary optimization of a complete infrared suppression system deserves further investigation.

关键词： Helicopter Infrared radiation Infrared suppression Internal aerodynamics Mixer-ejector

Numerical Study of Flow and Heat Transfer Characteristics of Impingement/Effusion Cooling

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Chinese Journal of Aeronautics 2009年第4期22卷 343-348页

作者： Zhang jingzhou Xie Hao Yang Chengfeng College of Energy and Power Engineering Nanjing University of Aeronautics and Astronautics Nanjing 210016 China College of Power Engineering Nanjing Normal University Nanjing 210042 China

Three-dimensional numerical simulation is carried out to investigate the flow and heat transfer characteristics of impingement/effusion cooling systems. The impingement/effusion holes are arranged on two parallel perforated plates respectively in a staggered manner. Every effusion hole has an inclined angle of 30° with respect to the surface. The two parallel plates are spaced three times the diameter of the effusion hole. The ratio of center-to-center spacing of adjacent holes to the diameter of the effusion hole is set to be 3.0, 4.0 and 5.0 respectively. The flow field, temperature field and wall film cooling effectiveness are calculated for different blowing ratios ranging from 0.5 to 1.5. In general, the wall cooling effectiveness increases as the center-to-center spacing of adjacent holes decreases or the blowing ratio increases.

关键词： impingement/effusion blowing ratio cooling effectiveness heat transfer numerical simulation

Experimental and numerical investigations on convective heat transfer of dual piezoelectric fans

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Science China(Technological Sciences) 2018年第2期61卷 232-241页

作者： li xinjun zhang jingzhou tan xiaoming college of energy and power engineering nanjing university of aeronautics and astronauticsNanjing 210016China

An investigation is performed to study the convective heat transfer performance under dual piezoelectric fans. Three main aspects are involved in the current study. Firstly, vibration tests for dual specific piezoelectric fans actuating at the first-mode resonant frequency are conducted to illustrate the influence roles of vibrating phase difference and fan-to-fan pitch on the piezoelectric fan vibration amplitude. Secondly, heat transfer measurements are made to compare the heat transfer among single fan, dual fans in-phase and dual fans out-of-phase. Thirdly, three-dimensional numerical simulations are conducted to reveal the influence mechanism of dual piezoelectric fans on heat transfer. The results show that, the vibrating phase difference of dual fans has nearly no influence on the displacement velocity and amplitude of piezoelectric fan related to single fan once the dimensionless pitch(P/W) is beyond 1.2. The dual piezoelectric fans produce nearly the same peak heat transfer coefficient as that of single fan *** particular is that the dual fans operating in-phase produce more favorable heat transfer than the dual fans operating out-of-phase,especially in the gap zone between dual fans. Due to the interaction between dual fans, the streaming flow induced by one vibrating fan suffers the action of sweeping flow of another vibrating fan when they operate out-of-phase. While for the dual fans operating in-phase, the streaming flows induced by vibrating fans merge together to form stronger wall jet flow in the region between two fans.

关键词： piezoelectric fan dual fans convective heat transfer numerical simulation

Recent advances in film cooling enhancement:A review

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Chinese Journal of Aeronautics 2020年第4期33卷 1119-1136页

作者： jingzhou ZHANG Shengchang ZHANG Chunhua WANG Xiaoming TAN Jiangsu Province Key Laboratory of Aerospace Power System College of Energy and Power EngineeringNanjing University of Aeronautics and AstronauticsNanjing 210016China

Film cooling is an indispensable scheme in the design of highly-efficient cooling configurations to satisfy the thermal protection requirement of turbine hot section *** the last few decades,vast efforts have been paid on the discrete-hole film cooling *** this paper,some of the recent literatures related to the passive strategies(such as shaped film cooling holes,upstream ramps,shallow trenches,mesh-fed slots)and the active strategies(such as the use of pulsation modulating device or plasma actuator)for film cooling enhancement are surveyed,with the aim at presenting an updated overview about the state of the art in advanced film *** addition,some challenging issues are also outlined to motivate further investigations in such a broad topic.

关键词： Active strategy Cooling capacity Discrete-hole film cooling Film cooling enhancement Jet-in-crossflow Passive strategy

Control of squealer-tip leakage flow with perforated-rib coolant injection in an axial turbine cascade

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Chinese Journal of Aeronautics 2023年第8期36卷 54-73页

作者： Shengchang ZHANG Qinqin WANG Xiaoming TAN jingzhou ZHANG College of Energy and Power Engineering Nanjing University of Aeronautics and AstronauticsNanjing 210016China School of Energy and Power Engineering Beihang UniversityBeijing 100191China AECC Sichuan Gas Turbine Research Establishment Chengdu 610500China

A novel perforated-rib configuration is proposed for controlling the tip leakage flow at the rotor tip of an axial *** perforated-rib layouts are considered,wherein a perforated rib is installed at(A)the Suction-Side squealer(SS-rib),(B)the Pressure-Side squealer(PS-rib),and(C)the additional squealer along the blade Camber Line(CL-rib).A numerical method is used to show how the novel rib layouts affect the aerodynamic performance of the tip leakage *** show that the coolant jets issuing from the perforated-rib injection holes penetrate deeper into the tip clearance than those in the baseline squealer-tip case,and how the perforated-rib coolant injection affects the tip leakage flow depends strongly on the rib *** PS-rib and CL-rib layouts appear promising for controlling the tip leakage flow,playing a significant role in reducing the total pressure loss and improving the turbine blade’s isentropic *** particular,under an injection mass flow ratio of 1%and a tip clearance of 1%blade span,the PS-rib layout reduces the leakage mass flow rate by 27%and increases the isentropic efficiency by 1.25%compared with those in the baseline squealer-tip ***,the advantages of the PS-rib layout in tip leakage control are confirmed under small and large tip clearances.

关键词： Aerodynamics Perforatedrib Squealer tip Tip injection Tipleakageflow

Convective heat transfer on flat and concave surfaces subjected to an impinging jet form lobed nozzle

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Science China(Technological Sciences) 2020年第1期63卷 116-127页

作者： LYU YuanWei ZHANG jingzhou WANG BoYan TAN XiaoMing College of Energy and Power Engineering Nanjing University of Aeronautics and Astronautics

A tri-dimensional lobed nozzle is concerned in the jet impingement on a flat target and a concave target in the current study. The jet impingement heat transfer experiments are conducted under two jet Reynolds numbers(Re=10000 and 20000) and four nozzle-to-surface distances(H/d=2, 4, 6 and 8). Simultaneously, to characterize the flow dynamics of lobed jet impingement onto different target surfaces, some computations are conducted under a specific jet Reynolds number. The results show that the lobed jet is capable of achieving an increase of stagnation Nusselt number about 25% in relative to the round jet at small nozzle-tosurface distances. However, at large nozzle-to-surface distances, the lobed jet otherwise weakens the convective heat transfer in the vicinity of jet stagnation, especially under high jet Reynolds number. When compared to the flat target, approximately a20%–30% reduction of stagnation Nusselt number is produced on a concave target, which is attributed to the combined effect of destabilization and confinement due to the concave curvature.

关键词： jet impingement enhanced heat transfer lobed nozzle flat surface concave surface

Experimental study on heat transfer characteristics of synthetic jet driven by piston actuator

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Science China(Technological Sciences) 2012年第6期55卷 1732-1738页

作者： GAO Shan ZHANG jingzhou TAN XiaoMing Shenyang Aeroengine Design and Research Institute Shenyang 110015China College of Energy and Power Engineering Nanjing University of Aeronautics and AstronauticsNanjing 210016China

Experimental investigation was conducted to investigate the impingement heat transfer performance of a synthetic jet driven by piston actuator on a constant heat flux surface. Effects of jet formation frequency, nozzle-to-surface spacing ratio and con- jugation of cross flow were considered. The synthetic jet is of stronger penetration and heat transfer capacity when the piston reciprocates at relatively high frequency. Similar to the continuous jet impingement, nozzle-to-surface spacing ratio plays an important role in the heat transfer enhancement of synthetic jet. The optimum nozzle-to-surface spacing ratio corresponding to maximum heat transfer enhancement is considerably high in the synthetic jet, as compared to that in a continuous jet, which indicates that the synthetic jet introduces a stronger entrainment and more vigorous penetration in the surrounding fluid. The convective heat transfer capacity is enhanced significantly under the conjugate action of a synthetic jet and cross flow in com- narison with their individual action.

关键词： synthetic jet impinging cooling cross flow heat transfer

Optimization for aerodynamic performance of double serpentine nozzles with spanwise offsets using Taguchi-based CFD analysis

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Chinese Journal of Aeronautics 2023年第5期36卷 1-17页

作者： Xuyong ZHANG Yong SHAN jingzhou ZHANG Zhongcheng WU College of Energy and Power Engineering Nanjing University of Aeronautics and AstronauticsNanjing 210016China

Serpentine nozzles are widely used in combat aircraft to realize strong stealth *** on the layout characteristics within a confined space,a series of double serpentine nozzles with spanwise offsets are *** computational fluid dynamics and Taguchi method,the influence mechanisms of the Distribution of Area(DA),Distributions of Centerline for the first and second‘S’sections in the Vertical direction(DCV1 and DCV2),and Distribution of Centerline in the Spanwise direction(DCS)are *** impact of these factors on the total pressure recovery coefficient can be ranked as DA>DCV2>DCS>DCV1,whereas their impacts on the discharge coefficient and axial thrust coefficient can be ranked as DCV2>DCS>DA>*** the statistical significance of these factors,a nozzle in which DA changes rapidly at the exit and DCV1,DCV2,and DCS change rapidly at the entrance gives the best aerodynamic *** to the worst configuration,the total pressure recovery coefficient,discharge coefficient,and axial thrust coefficient are improved by 1.6%,3.5%and 3.6%,*** influences the gas flow acceleration in the entire serpentine channel,resulting in different wall shear stress and friction *** various centerline distributions influence the gas flow acceleration effects and form complex wave structures in the constantarea extension section,resulting in different local and friction losses.

关键词： Aerodynamics Analysis of Variance(ANOVA) Computational Fluid Dynamics(CFD) Double serpentine nozzle Spanwise offset Taguchi methods

Experimental study of single-row chevron-jet impingement heat transfer on concave surfaces with different curvatures

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Chinese Journal of Aeronautics 2019年第10期32卷 2275-2285页

作者： Yuanwei LYU jingzhou ZHANG Xichen LIU Yong SHAN Jiangsu Province Key Laboratory of Aerospace Power System College of Energy and Power Engineering Nanjing University of Aeronautics and Astronautics

To address the curvature effect on single-row chevron-nozzle jet impingement heat transfer on concave surface,a series of experiments are conducted in the present *** concave surfaces including one semi-cylindrical concave surface and three parabolic concave surfaces with different width-to-depth ratios are tested under three typical Reynolds numbers(Re=5000,10000 and 15000)and several dimensionless nozzle-to-surface distances ranging from 1 to *** results show that the concave curvature has a clear impact on chevron-nozzle jet impingement heat transfer,tightly dependent on jet Reynolds number and impinging *** general,the semicylindrical concave surface produces the highest longitudinally-averaged Nusselt number at the leading line of concave *** a low jet Reynolds number,the parabolic concave surface with a highly curved curvature produces higher longitudinally-averaged Nusselt number at the leading line and more uniform longitudinally-averaged Nusselt number distribution along the curvilinear ***,the longitudinally-averaged Nusselt number at the leading line of concave surface is the lowest for the highly curved surface under a high jet Reynolds number and large impinging *** comparison with the round-nozzle,chevron nozzle plays a more significant role on improving jet impingement heat transfer at small impinging distances.

关键词： Chevron nozzle Concave surface Experimental test Heat transfer Jet impingement