Xiao H.,Xi'an University of Science and Technology |
Gao C.,Xi'an University of Science and Technology |
Dang Y.-Q.,The First Aircraft Institute
Shiyan Liuti Lixue/Journal of Experiments in Fluid Mechanics | Year: 2011
The waverider configuration is an important configuration of hypersonic cruise vehicle. Hypersonic flow around a multi-objective optimization designed waverider is experimentally studied by pressure measurement, force measurement and Schlieren observation at M=6 and 7 and angle of attack ranging from -4° to 8°. The results show that the aerodynamic characteristics of all the components of the waverider are good. The forebody precompression quality meets the design requirements well, the forebody shock is exactly caught by the lip of the inlet and the flow is quickly expanded at the aft body.
Yang C.-F.,The First Aircraft Institute |
Zhang J.-Z.,Nanjing University of Aeronautics and Astronautics
Experimental Thermal and Fluid Science | Year: 2012
Experimental study was conducted to investigate the enhanced cooling performance caused by ridge-shaped tabs located along the upstream edge of the film cooling holes. Three covering ratios of ridge-shaped tab on film hole and four blowing ratios were considered in the present. The results show that the presence of ridge-shaped tabs in the nearby region of the primary film cooling holes mitigates the primary vortices due to mainstream-coolant jet interaction in the downstream region. The lower penetration of coolant jet provides an increment in the film cooling effectiveness and also enhance heat transfer coefficient over the baseline case. The ridge-shaped tabs provide enhancements in cooling effectiveness, but this is at the expense of larger pressure drop, especially for ridge-shaped tabs with bigger covering ratio. © 2011 Elsevier Inc.
Feng Y.,Northwestern Polytechnical University |
Liu S.,Northwestern Polytechnical University |
Xue X.,Northwestern Polytechnical University |
Cui S.,Chinese Academy of Sciences |
Pan W.,The First Aircraft Institute
Hangkong Xuebao/Acta Aeronautica et Astronautica Sinica | Year: 2015
The sinking velocity of carrier-based aircraft is an important input for landing gear design and has a great influence on the weight of the landing gear and airframe structure. Aimed at exploring the effect of the various related landing parameters on sinking velocity for carrier-based aircraft in the actual service environment and based on E-2C measured landing data, correlation analysis of multivariate statistics is applied to the impact analysis of landing parameters on sinking velocity. Seventeen landing parameters are analyzed in the compaction-analysis and the results show that aircraft glide path angle and deck pitch angle are highly correlated with sinking velocity; engaging velocity is moderately correlated with sinking velocity. These three parameters have a great influence on sinking velocity. Nonlinear regression analysis is carried out on the four landing parameters and a fitting equation of E-2C sinking velocity is obtained. The coefficient of determination of the regression model is 0.991 and the mean absolute error is 1.66%, thus the model provides a preferable fitting effect. © 2015, Press of Chinese Journal of Aeronautics. All right reserved.
Xu F.,Beijing Aeronautical Science and Technology Research Institute |
Guo Y.F.,The First Aircraft Institute |
Chen L.,Beijing Aeronautical Science and Technology Research Institute |
Yang J.,Beijing Aeronautical Science and Technology Research Institute
Advanced Materials Research | Year: 2013
With the diversification of manufacture methods, joining the same materials with different states becomes indispensable in practical application. The hybrid welding has broad application prospects. It not only reduces the strict assembled gap before welding, but also improves the joint properties by filling wire during the welding process. 6061 aluminum alloys with different states were welded by YAG-MIG hybrid welding. The characteristics of welded joint, including microstructures, the tensile properties, microhardness and fracture, were investigated. The results show that the microstructures are different significantly in different states. Besides, the grain boundaries of the joint microstructures become unclear after heat treating. The strength and the elongations of welded joints could reach to that of the base metal. The tensile fracture occurs in the fusion zone and near 6061-O alloy. And the fracture presents ductile rupture. Meanwhile, the effect of the small pores in the weld on the joint's tensile properties is slight. © (2013) Trans Tech Publications, Switzerland.
Cao X.,The First Aircraft Institute |
Yang J.,The First Aircraft Institute |
Han X.,Northwestern Polytechnical University
Fuhe Cailiao Xuebao/Acta Materiae Compositae Sinica | Year: 2012
A kind of stitching line computation model was proposed to research the effect of stitching parameters on the strain concentration and stress concentration around the hole edge for the stitching-reinforced composite laminate containing a circular hole, such as the stitching needle distance, the row spacing, the edge distance and the modulus of stitching line, etc. The stress and strain distribution regularity around the hole edge and the nearby region were investigated analytically by combining the finite element computational results with experimental results, and an appropriate design method about the stitching parameter on the edge of hole as well as some pertinent conclusions was gaved. Research shows that different stitching parameters have obvious effect on the strain concentration and stress concentration around the hole edge.
Ji H.,The First Aircraft Institute |
Zhang C.,Northwestern Polytechnical University |
Qiao S.,Northwestern Polytechnical University
Xiyou Jinshu Cailiao Yu Gongcheng/Rare Metal Materials and Engineering | Year: 2015
6061-O and 6061-T4 aluminum alloy sheets with 0.04 inch (1.02 mm) nominal thickness are widely used in the aviation industry. After argon arc welding, the sheets were subjected to a solution heat treatment followed by a quenching and tempering treatment (T62 treatment), afterwards fabricated to specimens. The fatigue tests were carried out at 60 Hz, stress ratio of 0.1 both in atmosphere and water at room temperature, and loading direction was perpendicular to welding bead. The fracture morphologies were examined by scanning electron microscopy (SEM). The results show that the fatigue life in water is considerably decreased, and fatigue striation is not so clear compared with that in atmosphere, which might be attributed to the fact that the oxygen content on the fracture surface tested in water after dry treatment is much higher than that in atmosphere. Copyright © 2015, Northwest Institute for Nonferrous Metal Research. Published by Elsevier BV. All rights reserved.
Jiang J.,Northwestern Polytechnical University |
Zhang Y.,The First Aircraft Institute |
Sun Q.,Northwestern Polytechnical University
Nanjing Hangkong Hangtian Daxue Xuebao/Journal of Nanjing University of Aeronautics and Astronautics | Year: 2010
To simulate the progressive fracture of the bolted structure, a Global/Local analysis strategy is used. In both Global and Local coordinates, the nonlinear finite element analysis with EWK fracture subroutine is carried out. The result shows that the dangerous zone is located near the edge of the bolt hole. Failure element begins to appear when the applied load is up to 42% of the maximal load, then the crack spreads stablely along the circle of the bolt hole edge till the applied load reaches 48% of the maximal load. The crack spreads instantly afterward, thus leading to the collapse of the whole structure. The Global/Local analysis strategy can improve the efficiency of the entire analysis process.
Xin L.,Northwestern Polytechnical University |
Bai J.,Northwestern Polytechnical University |
Dong J.,The First Aircraft Institute |
Liu Y.,Northwestern Polytechnical University
Kongqi Donglixue Xuebao/Acta Aerodynamica Sinica | Year: 2015
Based on the N-S equations of multi-block structural grid and the method of structure flexibility coefficient matrix, an approach to CFD/CSD non-linear coupling problem based on radial basis functions (RBF) interpolation technology is established, RBF&Delaunay mesh motion method is adopted, which is used to compute the non-linear aeroelasticity of flexible aircraft with high aspect radio. This method is validated using DLR F6 configuration simulation. According to this method, static aeroelasficities of a civil aircraft under no jet/jet condition are investigated, showing that the engine jet can make wing plus twist, which is weaken wing sweepback effect, then the leading and trailing edge bending deformation increase and most of the favorable current profile twist angles decrease. Studies show that under the powered condition, the pressure distribution of rigid wing is changed, its lift confficient is reduced. The static aeroelastic deformation is a coupling effect, where the engine jet region is mainly influenced by jet while the outer wing is mainly by elastic deformation. The result of numerical simulation demonstrates that considering the aeroelasticity effect for no jet condition, the lift coefficient decreases by about 16% and the lift drag radio decreases by 8.4%. Whereas for powered case, the lift coefficient decreases by 18%, the lift drag radio decreases by 36%. Therefore, it is necessary to analyze static aeroelasticity of high aspect radio civil aircraft under powered condition. ©, 2015, Editorial Office of Acta Aerodynamica Sinica. All right reserved.
Wang C.,Northwestern Polytechnical University |
Song B.,Northwestern Polytechnical University |
Huang P.,Northwestern Polytechnical University |
Tang C.,the First Aircraft Institute
Journal of Intelligent and Robotic Systems: Theory and Applications | Year: 2016
This work proposes a hierarchical nonlinear control scheme for quadrotor to track 3D trajectory subject to payload variation and fast time-varying wind gust disturbance. In terms of dynamics model, the 6 DOF dynamics model with parametric and nonparametric uncertainties is built up. Wind gust and propeller momentum drag model are implemented to quantify the wind impact (force and moment disturbances) on quadrotor. In terms of control design, adaptive robust controller is developed for dynamic subsystem to deal with moment disturbance and estimate the system parameters. Global sliding mode controller is implemented for kinematic subsystem to generate adequate desired attitude angles for tracking the planned 3D trajectory. Simulations and experiments under various conditions are carried out for verification, and the results indicate the effectiveness, adaptiveness and robustness of the control strategy. © 2016 Springer Science+Business Media Dordrecht
Yin Z.,Northwestern Polytechnical University |
Li Y.,The First Aircraft Institute |
Tan S.,The First Aircraft Institute
Jixie Qiangdu/Journal of Mechanical Strength | Year: 2010
Under the abnormal landing, the aircraft structure must guarantee the safety of passengers according to China Civil Aviation Regulations 23(CCAR 23). For the first time, the crashworthiness model of some civil aircraft fuselage structure is carried out. The influence of crash velocity has been taken into account. Under different crash velocity, the acceleration of floor, impact force, and energy absorption capability have been analyzed. Numerical results show that horizontal velocity influences the impact force, energy absorption, and acceleration of the floor. And some horizontal velocity is beneficial for crashworthiness of the aircraft structure. And these provide a reference for reliability design and evaluation of this aircraft.