Special Issue / Special Column

Progress in numerical research on interface heterogeneous catalysis of hypers...

YANG Xiaofeng, LI Qin, DU Yanxia, LIU Lei, GUI Yewei

doi:10.7527/S1000-6893.2021.25908

2021, (12): 625908-625908.

Abstract

With the new demand for high speed and long endurance of future near-space hypersonic vehicle, the interaction between high-temperature flow and thermal protection system of near-space hypersonic vehicles is prominent under extreme mechanical and thermal conditions, causing such high-temperature interface effects as heterogeneous catalysis at the gas-solid interface. The theoretical modeling and numerical research history of interface heterogeneous catalysis in hypersonic vehicles are recalled. For interface heterogeneous catalysis modeling, the specific rate efficiency model, the phenomenological model with micro- or meso-scale properties, and the cross-scale model based on microscopic theoretical simulation are reviewed in details. The research progress of modeling, mechanism and application related with the interface heterogeneous catalysis effect in the authors' team are summarized. Focusing on the future hypersonic vehicle design requirements for weight reduction, range extension,...

A review on evolution characteristics of nanoparticles in gas-solid two-phase...

SHI Ruifang, LIN Jianzhong

doi:10.7527/S1000-6893.2021.25825

2021, (12): 625825-625825.

Abstract

The gas-solid two-phase turbulent flow with nanoparticles is very common in many fields including aviation. In the flow field, the nanoparticles, in the form of monomer and aggregate, undergo the processes of generation, convection, diffusion, coagulation and breakage, while the number density, scale and scale dispersion of particles will change. In this paper, we review the above research and draw the following main conclusions:Particle formation is caused by surface cooling, adiabatic expansion or mixing, turbulent mixing or supersaturation of condensable vapor produced by gas-phase chemical reaction; the causes of particle coagulation include Brownian motion, turbulent shear, velocity gradient and differential settlement; particle coagulation depends on particle size and flow field characteristics, and is controlled by initial particle distribution and turbulent diffusion; the influence of turbulence field on particle coagulation is not only the turbulence intensity, but also the fl...

Active subspace methods for analysis and optimization of turbulent combustion

WANG Nana, XIE Qing, SU Xingyu, REN Zhuyin

doi:10.7527/S1000-6893.2021.25228

2021, (12): 625228-625228.

Abstract

The demands for high efficiency and low emissions have driven the engines to near-limit combustion, leading to an urgent need for the development of innovative methods to analyze and modulate turbulent flames for stable combustion. There is a huge number of parameters affecting the flames. The quantity of predicted targets in turbulent flames varies primarily along a few directions in the space of input parameters. The classic global sensitivity measures to determine the most influential parameters perform poorly when the directions of variability are not aligned with the natural coordinates of the input space. We present the active subspace methods to first detect the directions of the strongest variability using evaluations of the gradient and subsequently exploit these directions to construct a response surface on a low-dimensional subspace-i.e., the active subspace of the inputs. With the active subspace methods, a theoretical framework has been formulated to efficiently quantify t...

Progress of mesoscale modeling and investigation of combustion multiphase flo...

XU Aiguo, SHAN Yiming, CHEN Feng, GAN Yanbiao, LIN Chuandong

doi:10.7527/S1000-6893.2021.25842

2021, (12): 625842-625842.

Abstract

Traditional computational fluid dynamics based on solving Navier-Stokes equations has achieved great success in many fields, but it has also encountered new bottlenecks and challenges in aerospace, microfluidic and other fields. The reasons can be divided into two aspects:(A) the problem of physical modeling; (B) the numerical accuracy and stability caused by discrete scheme. Reasonable and functional physical model is the premise of numerical simulation research. Problems at the level of physical modeling cannot be solved by improving numerical accuracy. A series of new concepts of combustion such as micro-scale combustion remind us that these more abundant but previously poorly understood characteristics of non-equilibrium behavior contains a large number of physical functions to be explored. In this paper we review the progress of Discrete Boltzmann Modeling method (DBM) for nonequilibrium combustion from the perspective of physical modeling and complex physical field analysis. DBM ...

Research progress in atomization characteristics of non-Newtonian fluid jet

YANG Lijun, LIU Luhao, FU Qingfei

doi:10.7527/S1000-6893.2021.24974

2021, (12): 624974-624974.

Abstract

This paper summarizes the research progress in atomization characteristics of the non-Newtonian liquid jet. The theoretical method predicting the breakup features of the primary atomization of non-Newtonian jets is first illustrated, and the experimental observation and properties introduced. At the end of the primary atomization of non-Newtonian jets, the generated droplets would go through the secondary atomization in the high speed gaseous flow. Therefore, the experimental research progress, both domestically and abroad, in the secondary atomization of droplets is reviewed. The experimental results of non-Newtonian droplets are then compared, followed by the summary of the effects of incoming gaseous flow parameters on the key characteristics in the secondary atomization processes such as the breakup mode, critical Weber number and initial deformation time. In addition, the atomization model which is based on the breakup physical processes of droplets and can predict the average dro...

Mechanism of cavity collapse induced by multiple shock waves of different str...

WU Wangxia, WANG Bing, WANG Xiaoliang, LIU Qingquan

doi:10.7527/S1000-6893.2021.25894

2021, (12): 625894-625894.

Abstract

The cavity collapse induced by the shock wave, especially multiple shock waves, is a compressible multiphase problem which contains transient fluid dynamics and complex physical phenomena. As this problem widely exists in many application fields, for example the spacecraft fuel injection and the extracorporeal shock wave therapy processes, it is necessary to carry out detailed analyses on it. In this study, the interaction process between single/multiple shock waves and the cavity in liquid is numerically simulated based on our in-house compressible multiphase parallel platform. The procedures of wave evolution and cavity collapse under different initial shock wave configurations are investigated in detail. It is found that, comparing with the configuration of one single shock wave, the wave system structures in both the liquid flow field and the cavity are more complex under the configuration of multiple shock waves. However, the cavity collapse processes are quite similar under all t...

Numerical study on primary breakup characteristics of dual-layer rotating con...

SHEN Lixin, XING Fei, QIN La, SU Hao

doi:10.7527/S1000-6893.2021.25267

2021, (12): 625267-625267.

Abstract

To comprehensively deepen the understanding of the primary breakup mechanism of conical liquid sheets, this study numerically simulated the atomization process of dual-layer conical liquid sheets, focusing on the effects of pressure drop and coaxial rotating air on the primary breakup characteristics of the liquid sheet such as the macroscopic morphology of the dual-layer liquid sheet, the breakup mode and length of the liquid sheet, and the spray cone angle. The macroscopic morphology of the numerically calculated spray field was close to the experimental results, and the maximum errors of the numerically calculated spray cone angle and the Sauter mean diameter were 4.9% and 7.4%, respectively. The numerical results show that the participation of coaxially rotating air in the atomization will change the overall morphology of the spray field. With the increase of pressure drop and air velocity, the breakup mode and the dominant surface wave mode of the liquid sheet will be changed. The...

Mixing enhancement of supersonic wake shear layer

YU Min, YANG Wubing, SHEN Qing

doi:10.7527/S1000-6893.2021.25876

2021, (12): 625876-625876.

Abstract

The efficient mixing of fuel and air at supersonic speed is the main challenge of scramjet technology. Based on analysis of large eddy simulation and hydrodynamic stability, the methods of mixing enhancement are studied in the supersonic wake shear flow. The existence of a wake component alters the profile of mean velocity, and has an important influence on the hydrodynamic stability. The existence of a wake component makes the most unstable modes of mixing layer from the three-dimensional to the two-dimensional, and the frequency and growth rate of the most unstable wave increase. The method of mixing enhancement of introducing disturbances in the mixing layer is still effective based on the analysis of hydrodynamic stability. According to the stability analysis, the parameters of wavy wall are designed. The numerical simulations observe that the disturbance introduced by the two-dimensional wavy wall cannot grow and almost has no mixing enhancement effect, while the disturbance intro...

Development and testing of AECSC-JASMIN turbulent combustion simulation softw...

WANG Fang, WANG Yudong, JIANG Shengli, CHEN Jun, TANG Jun, XU Huasheng, LI Xiangyuan, XING Jingwen,

doi:10.7527/S1000-6893.2021.25003

2021, (12): 625003-625003.

Abstract

The complex geometry of the aero-engine combustion chambers and the strong nonlinear interaction between turbulence and chemical reactions require high precision characterization of the flow, combustion, and their interaction with high space-time resolution. Currently, the difficulty in numerical simulation of turbulent combustion in the combustion chamber remains one of the bottleneck problems. This article will introduce the main algorithm of the AECSC-JASMIN software, which is jointly developed by the Aeroengine Numerical Simulation Research Center of Beihang University, Institute of Applied Physics and Computational Mathematics, and CAEP Software Center for High-Performance Numerical Simulation, as well as the example verification of the software. It will be tested with Sandia`s jet flame, concave strut flame-holder, and single-head combustion chamber. Compared with the experimental data, the prediction results of the jet and concave strut flame-holder are consistent with the exper...

Rigid-elastic coupled flight dynamic modeling and air resonance stability ana...

WANG Luofeng, CHEN Renliang

doi:10.7527/S1000-6893.2020.24634

2021, (12): 124634-124634.

Abstract

This paper presents a rigid-elastic coupled flight dynamic modeling method for a Heavy Lift Helicopter (HLH), considering the inherent characteristics of heavy weight and slow rotational speed. The method bridges flight dynamics and coupled rotor-fuselage aeroelastic dynamics, expanding the interested range of frequency to 5 Hz with an additional consideration of the elastic fuselage and blades. Based on the impedance matching method, explicit coupled dynamic equations were derived to simulate the helicopter aeroelastic characteristics in real flight. Finally, this model was used to calculate and analyze the flight and air resonance characteristics for an example HLH in hover. The results show that rotor-fuselage coupling causes the progressive lag mode and fuselage bending mode to approach each other and then separate after arriving at the same point with the increase of the rotational speed, which might result in high frequency transient vibration. The regressive lag mode is unstable...

Direct numerical simulation of shock wave/turbulent boundary layer interactio...

SUN Dong, LIU Pengxin, SHEN Pengfei, TONG Fulin, GUO Qilong

doi:10.7527/S1000-6893.2020.24681

2021, (12): 124681-124681.

Abstract

The compressibility effect in the hypersonic shock wave/boundary layer interaction is much stronger than that in the supersonic interaction, and after the reattachment, the high local pressure and thermal load will form, thereby significantly influencing the flight safety of vehicles. The three-dimensionality of the shock wave/boundary layer interaction further complicates the flow structures, making them more difficult to predict. In this study, a direct numerical simulation on the hypersonic shock wave/boundary layer interaction is performed. The effects of G rtler vortices on the separation bubble, the wall pressure and the heat flux are investigated both qualitatively and quantitatively. The investigation results indicate that the separation bubble exhibits obvious three-dimensionality and the size of the bubble at the spanwise separation location is significantly smaller than that at the spanwise reattachment location. The bubbles at the two locations change synchronously. The pre...

Multidisplinary interactions numerical simulation for active control of delta...

YANG Qi, LIU Wei, YANG Xiaoliang, LI Hao

doi:10.7527/S1000-6893.2020.24685

2021, (12): 124685-124685.

Abstract

Modern aircraft with delta wings and small thickness ratios of inner fuselages often fly at high angles of attack, resulting in wing rock motion due to the lack of lateral damp, which seriously threaten the flight safety. A multidisciplinary numerical simulation method has been established to control the wing rock motion, integrating aerodynamics, flight mechanics and flight control characteristics. The active control progress of delta wing with trailing-edge control surfaces is investigated by solving unsteady Navier-Stokes equations on moving grids and rigid body motion functions with one degree of freedom under classical control laws. Furthermore, the kinetic characteristics of the controlled delta wing in different control states are analyzed. The numerical results indicate that the wing rock motion of the 80° sweep delta wing has been controlled effectively with the inlet Mach number of 0.3.

Aerodynamic performance of double swept waverider based on projection method

LI Jun, YI Huaixi, WANG Dou, LUO Shibin

doi:10.7527/S1000-6893.2021.24703

2021, (12): 124703-124703.

Abstract

The double sweepback layout can effectively improve the aerodynamic performance of the waverider in the subsonic state. At present, the double swept waverider is mainly designed by the osculating-cones method with leading edge-customized. However, there are still some problems in this method, such as complexity of the design process and inconsistency between the actual and the theoretical inlet capture curve. Given that, we take the projection method to design the double swept waverider directly. To systematically research the aerodynamic performance of the double swept waverider obtained by the projection method at the subsonic and hypersonic speeds, the CFD method is applied. Results show that the aerodynamic performance of the double swept waverider designed by the projection method is equivalent to that designed with the leading edge-customized method in the hypersonic state. Moreover, the double swept waverider obtained by the projection method still retains the excellent aerodyna...

Air wake suppression method based on direct lift and nonlinear dynamic invers...

LUO Fei, ZHANG Junhong, WANG Bo, TANG Ruilin, TANG Wei

doi:10.7527/S1000-6893.2020.24770

2021, (12): 124770-124770.

Abstract

In complicated combat and landing environments, the disturbances of the air wake remains one of the main sources of ship landing errors. Utilization of the rapidity and decoupling capabilities of the Direct Lift Control (DLC) in the gliding phase can significantly reduce the pilot's controlling burden during landing and improve the suppressing ability of the air wake. From the perspective of decoupling of trajectory adjustment and attitude stability, this paper proposes to implement a precision carrier landing control law scheme based on direct lift under the framework of Nonlinear Dynamic Inverse (NDI) control, and establishes an E-2C full aircraft simulation model containing ship wake disturbances for verification. The results show that the design of the carrier-based aircraft landing control law with the introduction of DLC in the NDI can achieve a stable attitude during the landing stage, and meanwhile, rapid decoupling to adjust the track error through the direct force. In the cas...

A mean-stress model including material cyclic constitutive in uniaxial fatigu...

LIU Binchao, BAO Rui, SUI Fucheng

doi:10.7527/S1000-6893.2020.24735

2021, (12): 224735-224735.

Abstract

To precisely consider the effects of mean stress in evaluating uniaxial constant-amplitude fatigue lifetime, this paper proposes a mean-stress model on the basis of driving-force models, and the main idea of proposed model is to introduce material cyclic constitutive. Qualitatively, the model is capable of describing the shapes of constant-life curves for various materials in broader range of given fatigue lifetime as well as cyclic stress ratio; quantitatively, the model is capable of predicting fatigue lifetime under other cyclic stress ratios with satisfying agreements. Moreover, a method to obtain model parameters is also proposed, which further reduces test costs while ensuring the reliability of fitted data. The proposed mean-stress model possesses the potential to provide supports for compiling handbooks of material fatigue properties, and to offer guidelines for improvements of relevant engineering approaches.

Parameterized simulation platform of turbine cooling film blade life reliabil...

JIA Beixi, LYU Zhenzhou, LEI Jingyu

doi:10.7527/S1000-6893.2020.24747

2021, (12): 224747-224747.

Abstract

There are management and parameterization problems in the multiple mode life reliability analysis of complicated structure as turbine cooling film blade. To solve these problems, engineering technologies and simulation platform of multiple mode life reliability analysis in the presence of random uncertainty are created, which contains parameterization of mesh and finite element analysis, multiple mode probability life prediction, as well as the life reliability analysis methods. It is an efficient and automatic tool for the multiple mode life reliability analysis of turbine cooling film blades. The platform is able to do the parameterization of mesh and finite element simulation, so that automatic computation can be done with different inputs. On the basis of current turbine cooling film blade material life test data linear heteroscedasticity regression, homovariance polynomial regression and nonlinear damage accumulation criterion, a probability life prediction model containing temper...

Multi-objective optimization design for joined-wing SensorCraft

HE Cheng, MA Dongli, JIA Yuhong, YANG Muqing, CHEN Gang

doi:10.7527/S1000-6893.2020.24761

2021, (12): 224761-224761.

Abstract

A multi-objective optimization design model comprehensively considering aerodynamics, structure, and radar performance is proposed to meet the special mission demand of the joined-wing SensorCraft. The improved class function/shape function transformation method is used to complete the shape parameterization, the wind tunnel test performed to verify the aerodynamic analysis model, and the structural weight estimation model of the joined-wing configuration built based on the engineering beam theory. Moreover, based on the radar distance equation, a mathematical model for performance estimation of the antenna inside the wing is established. Using this model, the influence of the installation position and performance evaluation of the embedded antenna on the airfoil selection, structural weight and aerodynamic characteristics can be considered during the optimization process, and the global optimal design is finally obtained. The optimization results of a case show that, compared with the...

Buckling interaction formulae of composite plates under combined axial compre...

CHEN Xiangming, CHEN Puhui, SUN Xiasheng, WANG Binwen, WANG Zhe, ZHANG Hui, CHAI Yanan

doi:10.7527/S1000-6893.2021.25417

2021, (12): 225417-225417.

Abstract

An interaction function is constructed using axial tension/compression and in-plane shear loads, and further expanded into a quadratic polynomial by power series. Based on mathematical principles and reasonable hypotheses, the polynomial coefficients are determined using the buckling load of the composite plate measured by a uniaxial test. The buckling interaction formulae of composite plates under combined axial tension/compression and shear loads are then established. The problem that the traditional buckling interaction formulae are not suitable for composite plates (particularly for unbalanced laminates) is thereby solved mathematically and rationally. The buckling interaction curves of four different unbalanced ply composite plates under axial tension/compression and shear loads are predicted with the interaction formulae proposed in this paper, and compared with the simulation results of the finite element eigenvalue method. The comparison shows a good agreement. For the traditio...

Resource allocation based on improved fireworks algorithm

ZOU Shiyu, LI Fuming, XIE Aiping, ZHOU Tao, LIU Peng

doi:10.7527/S1000-6893.2020.24716

2021, (12): 324716-324716.

Abstract

As a NP-hard problem, the resource allocation problem is a common mathematical problem in cloud computing, radio, satellite scheduling, multi-UAV collaborative task allocation, and many other fields. As an intelligent optimization algorithm, the fireworks algorithm has the ability to solve large-scale resource allocation problems, but also has some problems, such as low solving precision and probability to fall into locally optimal solution. To improve the computational efficiency and global optimization ability of the traditional fireworks algorithm, this paper proposes an improved fireworks algorithm, which uses the mutation operator in genetic algorithm to replace Gaussian mutation operation in the traditional fireworks algorithm and adds the simulated annealing process in each iteration. Finally, the performance of the algorithm is verified by simulation on a mathematical model for multi-UAV cooperative task assignment, and the results show that the algorithm is superior to other t...

Testability index determination method based on ROM model

YANG Peng, QIU Jing, LIU Guanjun, ZHANG Yong

doi:10.7527/S1000-6893.2020.24717

2021, (12): 324717-324717.

Abstract

Aiming at the lack of theoretical and practical testability index demonstration method in practice, a novel method based on the ROM(operational readiness, reliability and maintainability) model is proposed. Starting from the relational expression of operational readiness (O), reliability (R) and maintainability (M), we establish the relations among Mean Time Between Failure (MTBF), Mean Time to Repair (MTTR) and fault diagnosis rate, false alarm rate and Built in Test (BIT) failure rate and substitute them into the "ROM" formula, obtaining the relation between the operational readiness and testability parameters. The relations between testability parameters and the number of BITs (number of BITs) are further established and substituted into the "ROM" formula to achieve the relation between operational readiness and number of BITs. The optimal number of BITs can be obtained from the curve of operational readiness and number of BITs, and the best testability index is derived subsequently...

De-orbit strategy using Bang-Bang control for space tethered-combination

GUO Jia, PANG Zhaojun, YUE Shuai, DU Zhonghua

doi:10.7527/S1000-6893.2020.24738

2021, (12): 324738-324738.

Abstract

To enable better task accomplishment of space tethered-combination in space debris removal, we propose a de-orbit strategy using Bang-Bang thrust, which is closer to the engineering application. Firstly, a Bang-Bang controller with differential clearance is used to realize the Bang-Bang thrust acceleration of space tethered-combination. In the process of de-orbit using Bang-Bang thrust, the engine needs to be switched on and off repeatedly. Therefore, a new passive winch mechanism is designed to avoid the negative effects of engine switching. A sliding mode controller with input constraints is designed for radial thrust to suppress the in-plane swing of the tether-combination in the process of de-orbit, and the control is also realized by Bang-Bang thrust. The simulation results show that Bang-Bang thrust can achieve similar results with continuous thrust that suppress the in-plane swing angle in a narrow range. The de-orbit strategy can make space tethered-combination complete the mis...

Target recognition decision method based on cloud model and improved D-S evid...

YIN Dongliang, HUANG Xiaoying, WU Yanjie, HE Youchen, XIE Jingwei

doi:10.7527/S1000-6893.2020.24768

2021, (12): 324768-324768.

Abstract

In the decision-making system for target recognition, the ambiguity and uncertainty of multi-detector and multi-source information fusion and the conflict and mutual exclusion of the information obtained in each detection cycle will cause inaccurate recognition of the target. To solve this problem, a decision-making method for target recognition based on the cloud model and improved D-S (Dempster-Shafer) evidence theory is proposed. First, the linguistic evaluation value of target recognition accuracy is divided into different evaluation interval levels, and the information obtained from each detection period of each detector is converted into a cloud decision matrix based on the standard cloud of different evaluation levels to obtain the membership degree of each level of each period, and then a basic probability distribution function (mass function) is constructed. Second, based on the evidence theory, three types of parameters, namely conflict degree, difference degree, and dispersi...

Experimental study on progressive failure mechanism of thin-laminate bolted j...

CAO Yuejie, WEI Lingfeng, ZHANG Minghao, CAO Zengqiang

doi:10.7527/S1000-6893.2020.24667

2021, (12): 424667-424667.

Abstract

To understand the damage evolution and failure mechanism, the bolted joints of thin-ply laminated composites with single- and double-lap structures under quasi-static loading were studied experimentally. The specimens were observed using X-ray Microscopic Computerized Tomography (Micro-CT) scanning and Scanning Electron Microscope (SEM) imaging at special stages of the whole loading process to evaluate damage progression and deformation characteristics. The results show that the major failure modes of thin-ply laminates were found to be similar to those of conventional thick-ply laminates, including fiber breakage, matrix cracking, fiber kinking and fiber-matrix debonding. However, the major difference is that the common failure mode that has been reported in conventional thick-ply laminates, namely extensive delamination initiated from the bearing failure plane and tensile failure plane, was not seen in these thin-ply laminates due to the crack suppression ability of thin-ply prepreg....

Microstructure prediction of multi-directional forging of TA15 alloy based on...

LUO Junting, ZHAO Jingqi, YANG Zheyi, LIU Weipeng, ZHANG Chunxiang

doi:10.7527/S1000-6893.2020.24693

2021, (12): 424693-424693.

Abstract

The true stress-strain curve of hot deformation of TA15 alloy was constructed through the hot compression test. The constitutive equations for hot deformation in the temperature range of the dual-phase region and single-phase region of the alloy were then established. A dynamic recrystallization model of TA15 alloy was established based on the statistical data of dynamic recrystallization of hot compressed samples. With the help of the secondary development function provided by Deform, programming of related mathematical models was realized, the experimental plan was formulated by the orthogonal method, and then simulation of the microstructure evolution of the multi-directional forging deformation of the dual-phase region and single-phase region of TA15 alloy was realized. Through analysis of the orthogonal experiment results, the objects under the influence of various factors and the influence degree of the factors were obtained, and the optimal combination of factors for multi-direc...

Quasi-static tensile behavior and failure mechanism of laminated puncture CF/...

SHEN Gaofeng, WANG Zhenjun, LIU Fenghua, ZHANG Yingfeng, CAI Changchun, XU Zhifeng, YU Huan

doi:10.7527/S1000-6893.2020.24816

2021, (12): 424816-424816.

Abstract

A novel aluminum matrix composite reinforced with laminated puncture carbon fiber fabric (CF/Al composites) was prepared. The progressive damage and mechanical behavior of the composite subjected to quasi-static tensile loading were investigated by using test and micromechanical simulation method. The test results show that the tensile modulus, ultimate strength and fracture strain are 129.61 GPa, 630.14 MPa, and 0.75%, respectively, and the calculation errors of the above property parameters are -9.41%, 7.57% and 1.33%, respectively. The macroscopic stress-strain curve from the micromechanical simulation agrees well with the test result. At the initial tensile stage, local damages were found in the matrix alloy located between the warp and weft yarns. With the increase of tensile strain, these damage zones accumulated gradually and led to the transverse cracking of weft yarns and piercing yarns in sequence. Thereafter, the warp yarns and matrix alloy failed successively, leading to dr...