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    ACTA AERONAUTICAET ASTRONAUTICA SINICA    2015, 36 (7): 0-0.  
    Abstract4408)      PDF(pc) (20270KB)(116747)       Save
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    Research Progress on Mesh Deformation Method in Computational Aeroelasticity
    ZHANG Weiwei, GAO Chuanqiang, YE Zhengyin
    ACTA AERONAUTICAET ASTRONAUTICA SINICA    2014, 35 (2): 303-319.   DOI: 10.7527/S1000-6893.2013.0423
    Abstract4847)      PDF(pc) (12893KB)(88296)       Save

    Mesh deformation is a main method to implement the computational mesh deformation with a moving boundary in computational aeroelasticity. First, an investigation of the status of the current advances in the researches on mesh deformation is presented in this paper, and some common mesh deformation approaches in recent years are reviewed in detail, which are spring analogy method, elastic solid method, transfinite interpolation method, Delaunay graph method, radial basis function method and temperature analogy method. Besides, based on the established models, the existing methods can be classified into physical model method, mathematical interpolation method and hybrid approach. A brief introduction of each method is made on theoretical method and research advance. The main emphasis is on the difference among the three methods of advantages and disadvantages as well as properties including deformation capability, deformation quality and efficiency. As an important aspect in computational aeroelasticity, the calculation data transformation between flow field boundary and structure boundary is summarized as well. At last, the present problems of mesh deformation which are frequently encountered in computational aeroelasticity are discussed, and in order to meet the needs of projects, possible prospects in future mesh deformation investigations are also proposed.

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    Concept definition of new-generation multi-purpose manned spacecraft
    YANG Lei, ZHANG Bainan, GUO Bin, ZUO Guang, SHI Yong, HUANG Zhen
    ACTA AERONAUTICAET ASTRONAUTICA SINICA    2015, 36 (3): 703-713.   DOI: 10.7527/S1000-6893.2014.0355
    Abstract5158)      PDF(pc) (1609KB)(75188)       Save

    With the Shenzhou spacecraft entering into the stage of maturity, it is of necessity to launch the research and development of a new-generation multi-purpose manned spacecraft. In this paper, we firstly generalize the technological characteristics, the design concept and the status quo of the foreign new-generation manned spacecraft. Based on this, we summarize their technological trend, i.e., multi-task adaption, cost reduction, bluntbody aerodynamic configuration, high safety reliability and new lightweight materials. Then, we primarily analyze the task requirements of China's new-generation manned spacecraft, including low earth orbit flight mission, as well as manned flights to the Moon, the asteroid and the Mars. We basically set the parameters of the overall performance. Finally, we sort out the technological approaches of it and propose two design schemes, which could provide some reference for the research of China's new-generation manned spacecraft.

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    Moving targets TDOA/FDOA passive localization algorithm based on localization error refinement
    LIU Yang, YANG Le, GUO Fucheng, JIANG Wenli
    ACTA AERONAUTICAET ASTRONAUTICA SINICA    2015, 36 (5): 1617-1626.   DOI: 10.7527/S1000-6893.2015.0010
    Abstract4406)      PDF(pc) (2558KB)(73565)       Save

    For the two-stage weighted least squares (TSWLS) technique of passive source localization using time difference of arrival (TDOA) and frequency difference of arrival (FDOA) measurements, which has the problem that the root mean square error (RMSE) and localization bias is large as the measurement noise increases. Based on analyzing the factor influencing the performances of the TSWLS firstly and then improves the TSWLS via Taylor-series (TS) expansion technique. The first stage of the new algorithm is the same as the one of TSWLS. At the second stage of the new algorithm, the localization error of the first stage is identified through utilizing the first-order Taylor-series expansion. Through updating the first-stage localization error, the final localization output is obtained. Theoretical performance analysis shows that the proposed estimator can attain the Cramer-Rao lower bound (CRLB) accuracy. Computer simulations are used to contrast the new technique with the TSWLS algorithm, the iterative maximum likelihood method based on TS and the constrained total least squares (CTLS) algorithm in terms of their localization RMSE and the localization bias. The new algorithm whose complexity is almost the same as TSWLS, the RMSE and localization bias are lower than TSWLS, TS and CTLS algorithm.

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    ACTA AERONAUTICAET ASTRONAUTICA SINICA    2015, 36 (6): 0-0.  
    Abstract1432)      PDF(pc) (37750KB)(69859)       Save
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    LADRC-based trajectory tracking for unmanned helicopter
    WU Chao, WANG Haowen, ZHANG Yuwen, TAN Jianfeng, NI Xianping
    ACTA AERONAUTICAET ASTRONAUTICA SINICA    2015, 36 (2): 473-483.   DOI: 10.7527/S1000-6893.2014.0270
    Abstract4148)      PDF(pc) (5579KB)(55558)       Save

    Trajectory tracking control system is used for decoupling the control unmanned helicopter, which is a nonlinear system with multi-input/multi-output and strong coupling effects. In order to avoid the dependence on accuracy of unmanned helicopter physical parameters measurement and identification and to reduce external disturbance impact, a multi-loop controller based on linear active disturbance rejection control (LADRC) is proposed. At first, the flight dynamics model is built for unmanned helicopter X-Cell. The atmospheric disturbance model, which contains wind shear, turbulence and gust model, is also set up for accurate simulation of real flight environment. Secondly, X-Cell is trimmed for verifying the accuracy of dynamic model and trim algorithm. A set of calculation values is selected as the initial state and input of the subsequent simulation. Then attitude, velocity and position control loop are built based on the first-order and second-order LADRC controllers which are selected according to system order. Combined with the time-scale separation principle, the whole trajectory control system is constructed from inner loop to outer loop. After that, the stability of the system is analyzed. The characteristic roots show that the whole system becomes stable with the trajectory controller. Finally, flight simulation experiments under various disturbance conditions are performed. The results show that the established control system can achieve a good climbing figure-eight trajectory tracking. Compared with controller based on proportion integration differentiation(PID), the controller based on LADRC has better robustness and capability of anti-disturbance.

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    Reliability-based Multidisciplinary Design Optimization Integrating BLISCO and iPMA
    LIU Chengwu, JIN Xiaoxiong, LIU Yunping, LIU Jihong
    ACTA AERONAUTICAET ASTRONAUTICA SINICA    2014, 35 (11): 3054-3063.   DOI: 10.7527/S1000-6893.2014.0047
    Abstract3421)      PDF(pc) (2453KB)(51864)       Save

    To solve the inefficient problem of reliability-based multidisciplinary design optimization (RBMDO), which is caused by the nested optimization process and repeated iterations of multidisciplinary analysis and reliability analysis, a new method integrating Bi-level integrated system collaborative optimization (BLISCO) and improved performance measure approach (iPMA) is proposed. Firstly, with the sequential idea, the whole process is decoupled and the repeatedly reliability analysis of overall reliability model is avoided. Then, an efficient and suitable BLISCO strategy for dealing with the multidisciplinary design optimization (MDO) of complex engineering system is adopted, which abandons the consistency constraints of collaborative optimization as well as the complex analysis and approximate modeling problems of Bi-level integration system synthesis. Thirdly, the performance measure approach (PMA) is improved by updating angle strategy to evaluate the reliability, which can reduce a great number of multidisciplinary reliability analysis. Finally, a shock absorber design example of landing gear has been implemented to verify the efficiency of the proposed method. The results show that the efficiency of the proposed method has been improved by 30.93% and 19.97% respectively compared to the other two methods. Therefore, it is valuable in engineering design and optimization.

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    Effect of modal selection on static aeroelastic analysis
    DU Ziliang, WAN Zhiqiang, YANG Chao
    ACTA AERONAUTICAET ASTRONAUTICA SINICA    2015, 36 (4): 1128-1134.   DOI: 10.7527/S1000-6893.2014.0247
    Abstract2779)      PDF(pc) (4636KB)(50256)       Save

    The flexibility method and modal approach are usually used in structural analysis in the static aeroelastic research. Compared to the flexibility method which is mature but brings higher computational cost for the solution,the modal approach has the advantage of significant reduction in the dimension of the problem,high efficiency and convenient for verification. However, there are no principles for the selection of modes and one must have enough engineering experience to fully utilize the modal approach in practice. To provide modal approach with its own quantitative criteria in practice, this paper first proposes the idea of modal influence coefficient to evaluate the effect of modal selection on modal approach of aeroelastic analysis. In order to validate the rationality and validity of the modal influence coefficient, the paper carrys out control efficiency and aeroelastic correction analysis for a typical aircraft. The results show that the modal influence coefficient can accurately evaluate the effect of modal selection on static aeroelastic analysis, thus providing some helpful reference in practice.

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    Influence of fiber surface state on microstructure and phase composition of C/C-SiC composites
    DAI Jixiang, SHA Jianjun, WANG Shouhao, WANG Yongchang
    ACTA AERONAUTICAET ASTRONAUTICA SINICA    2015, 36 (5): 1704-1712.   DOI: 10.7527/S1000-6893.2014.0154
    Abstract3356)      PDF(pc) (4727KB)(45055)       Save

    In order to investigate the influence of fiber surface state on the microstructure and phase composition of C/C-SiC composites, the surface composition of carbon fibers is modified by heat treatment, and then the fibers with different surface compositions are used to fabricate the C/C-SiC composites via liquid silicon infiltration technique. The surface composition of carbon fibers is measured by XPS (X-ray photoelectron spectroscopy). Results reveal that the oxygen content on the surface of carbon fibers decreases with increasing the treatment temperature. The low oxygen content led to small numbers of oxygen-containing functional groups, resulting in small pore size and a high porosity in C/C perform. After infiltrating the liquid silicon into C/C preform, the morphologies of C/C-SiC composites are observed by scanning electron microscopy(SEM). It is found that the microstructure and phase composition of C/C-SiC composites are quite dependent on the surface composition of carbon fibers. With decreasing the oxygen content on the carbon fiber surface, the SiC content in matrix increased, but the residual Si is reduced. Particularly, in the case of fibers with low oxygen content on the surface, there is almost no residual Si in matrix, and the composites presented a more homogeneous distribution of SiC matrix. Based on the results mentioned above, it can be seen that the microstructure and phase composition of C/C-SiC composites are controlled by the size and distribution of pores, which is closely associated with the surface state of carbon fibers. For the C/C preform with large pore size, during the liquid silicon infiltration, the formation of SiC is dominated by the solution-precipitation reaction and the interface-limited diffusion reaction mechanisms. In the case of C/C preform with small pore size, the formation of SiC is mainly controlled by solution-precipitation reaction mechanism.

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    Investigation of sound generation by non-synchronously vibrating rotor blades
    ZHOU Di, WANG Xiaoyu, CHEN Jun, HONG Zhiliang, SUN Xiaofeng
    ACTA AERONAUTICAET ASTRONAUTICA SINICA    2015, 36 (3): 737-748.   DOI: 10.7527/S1000-6893.2015.0029
    Abstract1889)      PDF(pc) (1578KB)(39475)       Save

    The blade fatigue failure is a common aeroelastic problem of axial compressor. The phenomenon accompanied with blade vibration is abnormal acoustic field generation in compressor duct. The frequency of sound field generated by non-synchronously vibrating rotor blades is unequal not only to the compressor rotational frequency, but also to the blade passing frequency that is identical with sound generated by stator and rotor interaction. Meanwhile the frequency cannot be explained by typical Doppler shift phenomenon. In this paper, a theoretical model based on the three-dimensional lifting surface theory has been built to demonstrate the frequency and circumferential modal characteristics of the sound generated by rotor blades vibration. The developed model illuminates the fact that the sound frequency and circumferential mode depend a lot on the inter-blade phase angle. The experiment results verify the relationship between sound generation and blades vibration given by the model.

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    Effects of Titanium Surface Anodization on Adhesive Bonding Properties of TA2/polyetheretherketone(PEEK)
    XU Fei, PAN Lei, BAI Yunrui, CAO Jiameng, TAO Jie, TAO Haijun, CAI Lei
    ACTA AERONAUTICAET ASTRONAUTICA SINICA    2014, 35 (6): 1724-1732.   DOI: 10.7527/S1000-6893.2013.0447
    Abstract2843)      PDF(pc) (3362KB)(37454)       Save

    Surface treatment on titanium sheets by NaTESi anodization at constant voltage is conducted to improve the bonding properties of TA2/polyetheretherketone (PEEK) in TA2/Cf/PEEK laminates. The effects of technical parameters (such as voltage, time and temperature) on the single lap joint shear strength and the surface roughness of TiO2 film are investigated by an orthogonal test. It demonstrates that the most important factor affecting the bonding properties is time. Longer anodization times resuted in lower surface roughness, which contributed to inferior bonding properties. Properties of the TA2 laminate are investigated by XRD and SEM, and the results show that the optimized process which is favorable for the increase of the bonding strength is as follows: anodizing voltage 10 V, anodizing temperature 35℃ and anodizing time 10 min. The surface roughness treated by this method is 1.34 μm and the nano-particles morphology appeares, which the size of the particles is about 100-200 nm. The single lap joint shear strength with these parameters could reach 19 MPa. The resistance to delamination between the titanium sheet and PEEK in this optimized process is measured in a double cantilever beam test. The average energy release rate of the TA2/PEEK interface which was prepared by the method of NaTESi anodization is 188.1 J/m2, which showes an increase of 103.1% compared with the untreated ones. The results indicate that the anodizing process markedly enhance the delamination resistance of TA2/PEEK bonding interface.

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    Airfoil optimization based on improved CST parametric method and transition model
    WANG Xun, CAI Jinsheng, QU Kun, LIU Chuanzhen
    ACTA AERONAUTICAET ASTRONAUTICA SINICA    2015, 36 (2): 449-461.   DOI: 10.7527/S1000-6893.2014.0059
    Abstract3103)      PDF(pc) (4418KB)(30388)       Save

    In this paper, B-spline basis function is implemented in class and shape transformation (CST) parameterization method in place of the traditional Bezier polynomials to enhance the local ability of control and accuracy to represent an airfoil shape. To guarantee the requirements on geometric smoothing performance and proper orthogonal decomposition (POD) reconstruction accuracy in airfoil design optimization process, the local fairing method for multi-resolution airfoil is proposed based on the wavelet decomposition technique, expanding the design space. A surrogate model based on POD method and γ-Reθt transition predicting model is adopted to achieve fast and accurate prediction of aerodynamic forces and transition. The computed results of flow around airfoils show that the combined surrogate model is an effective method in design optimization of natural laminar airfoil. A complete aerodynamic design optimization system for natural laminar airfoil is constructed by integrating genetic algorithm, the improved CST parameterization method with wavelet decomposition fairing, POD surrogate model and γ-Reθt transition model. The system is used for the design optimization of low-speed and transonic airfoils, achieving an increase in lift-drag ratio of 47.42% and 45.85%, respectively, which validates the efficiency of the design optimization system proposed in this paper.

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    A Feature Point Extraction Method for Large Size Aerial Images
    SHI Xiangbin, ZHANG Jinsong, CHEN Runfeng, LIU Jinli
    ACTA AERONAUTICAET ASTRONAUTICA SINICA    2014, 35 (1): 240-248.   DOI: 10.7527/S1000-6893.2013.0326
    Abstract3812)      PDF(pc) (3748KB)(24870)       Save

    The existing feature point extraction methods usually cost a lot of CPU time when they are applied to large size aerial images. For the purpose of fast extraction of feature points in these large size aerial images, a novel method is developed. Usually these aerial images have not only large sizes but also wide ranges of shooting. They usually have different feature point performances on different scales and the distributions of spectra are uniform in the frequency domain. In this paper, the scales of the feature points are kept by employing the Laplacian pyramid, and a specified non-uniform N-dimensional directional filter bank is applied to decompose the pyramid images. The scales and the directions of the images are extracted. Then the local extreme points are extracted as a candidate feature points set. Finally, the candidate feature points in different directions are merged by a specified merge-strategy. Thus, we obtain the final feature points set and the directions of the feature point described by the direction filter bank. Experimental results are presented that demonstrate the proposed method is efficient for large size aerial images while meeting the match rate and precision rate requirements.

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    Progress in airframe-propulsion integration technology of air-breathing hypersonic vehicle
    WU Yingchuan, HE Yuanyuan, HE Wei, LE Jialing
    ACTA AERONAUTICAET ASTRONAUTICA SINICA    2015, 36 (1): 245-260.   DOI: 10.7527/S1000-6893.2014.0238
    Abstract3464)      PDF(pc) (29626KB)(24070)       Save

    Air-breathing hypersonic vehicle is highly integrated making its design challenging. All vehicle parts and functions interact including aerodynamics, propulsion, control, structure, tank and thermal protection, especially for airframe and scramjet engine coupling. The lower wall of the aircraft forebody and afterbody is either compression part of the engine inlet or expansion part of the engine nozzle and it produces lift and pitching moment as well as thrust. The strong coupling of the airframe and engine has direct influence to the thrust, lift, drag, pitching moment, aerodynamic heating, airframe cooling, stability and control characteristics of the vehicle. The research developments of airframe-propulsion integration technology are introduced and the related works of China Aerodynamics Research & Development Center (CARDC) are emphasized. These works included osculating curved cone waverider inlet design, double shockwave axissymetric flow field-based inward turning inlet design, airframe-propulsion integrated vehicle tests in pulsed combustion heated hypersonic high-temperature wind tunnels and hypersonic large-scale parallel numerical simulation platform (AHL3D). The related fundamental researches of hypersonic shock-boundary layer interaction, compressible turbulent transition of flow separation mechanism and its control, scramjet combustion study on flow mechanism and other related basic issues are introduced. The urgent need of efficient high-precision calculation method is emphasized.

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    Investigation of Airflow Allocation Inside High Pressure Turbine Rotor Blade
    ZHU Xingdan, TAN Xiaoming, GUO Wen, ZHANG Jingzhou, WANG Yongming
    ACTA AERONAUTICAET ASTRONAUTICA SINICA    2014, 35 (12): 3273-3782.   DOI: 10.7527/S1000-6893.2014.0193
    Abstract1274)      PDF(pc) (13136KB)(23836)       Save

    Conjugate heat transfer simulation is used to conduct investigations aiming at obtaining the cooling performance of the internal cooling structures of a certain turbine rotor blade in this paper. Effects of three different airflow allocation methods on the cooling effect of the blade are analyzed under the condition of the same total airflow. Subsequently, the cooling structure with the best cooling performance is chosen to discuss the influence of rotational speed on total inlet pressure and overall cooling effectiveness. The results show that Model B produces more reasonable airflow allocation, obtaining more uniform temperature distribution and higher overall cooling effectiveness. The cooling airflow deflects due to the existence of Coriolis force and centrifugal buoyancy force. The stagnation line located at the blade leading edge is forced to shift from pressure side to suction side with the increase of rotational speed and the film discharges are also changed with the rotational speed. The increasing rotational speed leads to an improvement on pressure surface cooling effectiveness and inversely a decrement on suction surface cooling effectiveness.

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    Axial Transonic Compressor Flow Instability Prediction Based on Eigenvalue Theory
    LIU Xiaohua, ZHOU Yanpei, SUN Dakun, MA Yunfei, SUN Xiaofeng
    ACTA AERONAUTICAET ASTRONAUTICA SINICA    2014, 35 (11): 2979-2991.   DOI: 10.7527/S1000-6893.2013.0499
    Abstract2319)      PDF(pc) (2559KB)(23213)       Save

    Flow instability is a great challenge in turbomachinery, and rotating stall is one major type of flow instability in compression system of aero-engine. In the present paper a rotating stall inception model based on a general eigenvalue theory of flow stability is developed with an emphasis on flow instability onset in axial transonic compressors. After solving the established eigenvalue equation using the spectral method and the singular value decomposition (SVD) method, the onset point of flow instability is determined by the imaginary part of the resultant eigenvalue. The significant effect of flow compressibility on the stall onset point calculation for a transonic rotor is studied by comparing the prediction results for a high speed single rotor at both high and low rotational speeds. The capacity of the present model to predict the stall inception point is assessed against the experimental data of a transonic single stage compressor. It is verified that this model is capable of predicting the mass flow at the stall onset point of a multi-stage transonic compressor flow with reasonable accuracy without numerous empirical data, and it is sustainable in terms of computation cost for industrial application.

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    AN EXPLICIT EXPRESSION OF THE TURBULENT FRICTIONAL DRAG COEFFICIENT FOR A FLAT PLATE
    Shi Changchun
    ACTA AERONAUTICAET ASTRONAUTICA SINICA    1988, 9 (6): 299-302.  
    Abstract4299)      PDF(pc) (232KB)(23084)       Save
    This paper presents some analytic expressions associated with those well-known skin-friction formulas for turbulent shear flows. Two methods were developed for this aim. The first one is an approximated analytic solution for the same super-algebraic equation; And the second one is a method of iteration and its convergence has been proven. The skin-friction formula of D.B.Spalding has also been improved in the present work.
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    Research of Visual Interaction for Virtual Reality Flight Training
    ZHOU Lai, ZHENG Danli, GU Hongbin, WANG Debao
    ACTA AERONAUTICAET ASTRONAUTICA SINICA    2013, 34 (10): 2391-2401.   DOI: 10.7527/S1000-6893.2013.0290
    Abstract2335)      PDF(pc) (8203KB)(22914)       Save

    Appearance-based hand pose estimation which relies on computer vision techniques is adopted to realize natural interaction in a semi-virtual reality cockpit. To cope with the low efficiency and high memory consumption in large capacity and high-dimension feature indexing, an improved locality sensitive Hashing (LSH) method is proposed in this paper which combines the multi-probe principle with the nearest-neighbor table. Moreover, a forecast model which predicts indexing performance and a parameter optimization method are used to achieve better indexing performance. Experimental results show that the forecast model is appropriate for practical indexing performances and the time consumption is reduced by 41.9% at the cost of a slight recall rate drop. In summary, the application of the improved LSH to hand pose estimations able to upgrade virtual hand visualization and hand posture reconstruction in a semi-virtual reality cockpit.

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    Study of Heat Transfer of Cryogenic Methane Under Supercritical Pressure with Consideration of Thermal Conduction in Engine Cooling Channel Walls
    CHEN Zunjing, WANG Leilei, MENG Hua
    ACTA AERONAUTICAET ASTRONAUTICA SINICA    2013, 34 (1): 8-18.   DOI: 10.7527/S1000-6893.2013.0002
    Abstract3678)      PDF(pc) (7541KB)(22373)       Save

    Numerical simulation study is conducted of the heat transfer of cryogenic methane flowing inside a rectangular engine cooling channel under supercritical pressure with consideration of the coupled thermal conduction in the solid channel region. The effects of wall heat fluxes and cooling channel geometries on the fluid flow and heat transfer processes under supercritical pressure are carefully examined. Variations of the fluid velocity, channel wall temperature, wall heat flux, and Nusselt number are obtained and discussed. Results indicate that with consideration of the conjugate heat transfer in both the solid and fluid regions, a fraction of the heat flux imposed on the top channel surface is transferred into the cryogenic methane through the side walls. As the imposed wall heat flux increases, more heat can be thermally conducted into the side channel walls. Decreasing the cooling channel height/width aspect ratio leads to enhanced heat transfer, but the pressure loss also increases significantly. Therefore, the combined effects of the channel aspect ratio on both heat transfer and pressure loss has to be taken into consideration to obtain an optimum cooling channel design. The thermal performance parameter can be used as a reference in this regard. The modified Jackson & Hall coefficient is applicable to heat transfer prediction under supercritical pressure with acceptable accuracy under all tested conditions in this paper.

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    GENERATION OF 3 D MUTLI BLOCKED STRUCTURE BODY FITTED GRIDS OF A COMPLEX CONFIGURATION FLYING BODY
    Zhu Junzheng;Fan Xijun
    ACTA AERONAUTICAET ASTRONAUTICA SINICA    1997, 18 (1): 62-66.  
    Abstract2524)      PDF(pc) (260KB)(21532)       Save

    A general generation method is presented for the 3 D multiply blocked structure grid of a complex configuration flying body.The structure grids can be generated by decomposing the domain into any number of contiguous blocks,and each physics region can be considered to have been transformed to a rectangular computational region on which the curvilinear coordinates are the independent variables.Thus the generated grid is not too skew or unregular.Effect of control functions on grid generation is discussed.The given examples showed that the method may deal with arbitrary complex 3 D domains with the multi blocked structure technique.

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