Abstract:Fuel tank damage caused by hydrodynamic ram has became increasingly widespread. Summary and analysis of the research of hydrodynamic ram in recent decades provide a reference for future research work. Hydrodynamic ram research has an early start, early experiment and theoretical analysis formed the theoretical basis. With the progress of the test apparatus and the introduction of finite element method, test results has became more and more accuracy, hydrodynamic ram effect research entered a new phase. But for the hydrodynamic ram effect, there are so many problems, they will be the focus of future work.

Abstract:Active Stability Control(ASC) can suppress compressor rotating stall and avoid surge, consequently reduce stability margin, expand operating range and maximize compressor performance. Research progress is reviewed for ASC technology and its engineering applications. As ASC key technologies, the application limitation and developing trend of Moore-Greitzer-based compressor modeling method and the main active control method: modal control and nonlinear control were analyzed. the analysis may provide reference for compressor ASC theory research and engineering applications.

Abstract:The performance programs and structual characteristics of the engine used by foreign heavy helicopters in service were analyzed and compared, then the technical characteristics, design ideas and development strategies of high-power turboshaft engine used by heavy helicopter were summarized. Combined with the direction of the future development of foreign advanced turboshaft engine, the tendency of future development of high power turboshaft engine was analyzed and given.

Abstract:The effect of length-depth ratio (L/D) on flow and aeroacoustic characteristics of cavity is studied using detached eddy simulation (DES) based on Realizable k-εturbulent model. The cavity is 0.508m long by 0.1016m and the depth is variable to obtain L/D ratio of 3,5,8,14,17. The Mach number is 0.85 and the Reynolds number is 6.84 × 106. The results indicate that L/D is significant on the pressure gradient and aeroacoustics, and the flow type changes gradually from open cavity flow to closed cavity flow with the increase of L/D. In addition, static pressure, fluctuating pressure and aeroacoustic characteristics must be considered when defining cavity flow types.

Abstract:A constructed one-zone inhomogeneous phenomenological model of Nanosecond Dielectric Barrier Discharge (NSDBD) is coupled with the unsteady Navier-Stokes equations to model the effects of nanosecond plasma actuation on flowfield. The coupled system is solved by using unsteady Reynolds-Averaged Navier-Stokes equations (URANS) which can predict the compression-expansion wave structures and wave speed well compared with experimental results and can be applied to simulate the flow control by using NSDBD. The model is adopted to investigate the separation control airfoil using NSDBD plasma actuator. The separation-control mechanisms over NACA0015 are investigated by using URANS and Large-Eddy Simulation (LES). It is found that the transition from laminar to turbulence can be promoted by plasma actuation, and that flow transition acts as an important factor in the flow-separation control. At the Begining of the actuation, each actuation can produce a spanwise vortex around the separation point near the leading edge. The spanwise vortices make the separated free-shear layer unstable and shedding away, move downstream along the upper wall, and bring outer flow with high kinetic energy into the near wall region to change the flow structures over the airfoil. Then, the flow around the leading edge of the airfoil reattach after encountering a separation bubble because of the earlier transition. At last, the flow on the upper surface of the airfoil become fully attached.

Abstract:From three aspects as safety, economy and comfort, build the measure index system of the technical level of the civil regional aircraft. Took the date of typical regional aircraft in the world as samples, used regression analysis method and founded a measure model to measure the technical level of civil regional aircraft in the world. Then, on the basis of the performance data of Chinese typical regional aircraft, using the measure model, analyzing the technical level of civil regional aircraft in our country. Found that the comprehensive technology level of Our country civil regional aircraft Y7-100 behind the world"s advanced level in the same period for 10.22 years, the comprehensive technology level of ARJ21-700 behind the world"s advanced level in the same period for 7.83 years and so on. Civil aircraft technical level has been improved obviously in our country, and the gaps in civil regional aircraft between China and the world"s advanced level is shrinking.

Abstract:Inflatable wings possess charming potential in airships and future morphing aircrafts. But the structural features of inflatable soft wing are obviously different with traditional hard wing, and there are many bumps on the profile of inflatable wing. The effects of these bumps on aerodynamical and aeroelastical behavior get increasing attention from researchers recently. This paper constructed the CFD models of smooth NACA0015 airfoil and bumpy inflatable wing(named 0015F2 airfoil) with CFX software. Numerical results show that 0015F2 airfoil has larger stall attack angle than NACA0015 airfoil, but the slope of the lift coefficients vs attack angel curve and the lift-drag ratio of bumpy wing is lower than the smooth NACA0015 airfoil. The effects of the bumps on boundary layer can be grasped though analysis of the velocity profiles normal to the surface at different chord locations. The bumpy airfoil promotes a thicker boundary layer than that of the smooth airfoil at the same chord locations. The unsteady simulations show that the vortices form within each vicinity of the bumps, and these vortices prevents the separation seen in the smooth airfoil simulations so that the stall angel of attack is increased.

Abstract:A finite element model of composite laminate with delamination damage was established to analysis the fatigue delamination propagation behavior of composite laminate, and took B-K standard based on the energy release rate as the criterion of delamination growth. The residual strength model was adopted and VUMAT user subroutine was introduced to judge the failure of model and reduce the stiffness performance of material. Based on the Abaqus simulation analysis software, the delamination growth mechanism of composite laminates with initial delamination damage under fatigue compression load was simulated. The results indicated that with the fatigue load applying, the delamination length increased and reached a stable value finally, while the delamination growth rate reduced, a good agreement was obtained between FEA analysis and the experimental results.

Abstract:The stress intensity factors of the integral wing beam structure with stopping-crack stringer are researched by use of FEM software ANSYS, and the crack propagating tests are achieved using simulate specimen. Results indicate that the value of the stress intensity factors have been a sharp decline due to the normal stress in the beam is shared by the stringer, and which is ability to share high static load so as to achieve fail-safe design before the crack extend to the stringer, nevertheless it is hard to stop the crack propagation by stringer. Beside, the shear stress in beam plate can’t serves to propagate model II crack since the ratio of the shear stress to the normal stress is smaller.

Abstract:In this paper, the developments of functionally graded materials and graded finite elements are reviewed. By taking into account of thermal and plastic behaviours of materials, a thermo-elasto-plastic graded finite element method has been derived. The method, being capable of describing spatially varying material properties, has been implemented in the commercial finite element code ABAQUS by using user-defined material subroutines for solving engineering problems. To illustrate the applicability of the method, a case example has been preformed to study the mechanical response of a ceramic-FGMs-metal sandwich structure. The merits of the method have discussed on the basis of the numerical results. Further developments of the method would be useful for skeletal muscle simulation.

Abstract:In order to estimate the landing gear system stability, the first domestic shimmy test on landing gear were implemented, where shimmy modes of landing gear were excited by the plank fixed on the runway. Based on mode lobe separation combined with least square method, the test data were analyzed through identifying the modal parameters. The method was validated by simulating data with theory solution, and applied to analyze certain shimmy test data. The results show that landing gear shimmy does not occur in the flight test, which indicates the landing gear is stable.

Abstract:In order to analyze the launch vehicle’s structural transient responses in the phases of HDSR, the hold-down and soft release(HDSR) take-off event of launch vehicle was divided into three phases, including the static phase, hold-down phase and the soft release phase. The fields function, selected group analysis function and the CBUSH1D element’s nonlineardisplacement vs. load function of MSC.Patran were also used. The other two commonly used release techniques of launch vehicle were also analyzed. The computational results indicated the HDSR technique can reduce the impact load acting on the launch vehicle and reduce the launch vehicle’s structural transient response effectively.

Abstract:Icing of plane will jeopardize it fight. The flow and droplet-impingement property of a three-dimensional model of DLR plane is analyzed thought Fensap.CFD method and Spalart–Allmaras turbulence model were used .Certain the influence of different environment parameter to droplet-impingement property by altering specified parameter and we can finally know the influence of environment to plane icing. The result indicate that：Higher velocity results in smaller water efficiency and smaller water diameter also results in smaller water efficiency.

Abstract:The criteria and requirements of flight flutter test are presented. The measurement technique、flight test method、flight test contents、excitation methods and data processing method of the civil transport airplane are studied taking use of ARJ21-700 certification flight flutter test. The compliance certification results are given for flight flutter test of ARJ21-700 aircraft. The results show that this set of methods are suitable for the civil transport airplane certification flight flutter test.

Abstract:The Maximum Likelihood (ML) estimation method has been extensively applied to identifying the parameters of an aircraft, but it has to derive sensitivity equations in advance and solve sensitivity matrices, thus being inconvenient for its application and easily reaching locally optimal solutions. The paper proposes an aircraft"s parameter identification algorithm by combining the cloud model optimization with the ML estimation method. The algorithm proposed in the paper satisfactorily overcomes the shortcomings of the ML estimation method. Its detailed procedural steps are presented. The numerical results show that the parameter identification algorithm is easy to implement, has good identification precision and fast convergence and does not reach locally optimal solutions.

Abstract:To research the dynamic flow field characteristics of main valve during the safety valve opening period, the user-defined function method and Fluent dynamic mesh method with virtual technic are used for initial fluid-structure interaction numerical simulation. The pressure force of diaphragm is obtained through solving the air-capacitor filling and exhausting process equation, while valve speed and displacement are solved through the mass-spring-damping system dynamic equation. Results show that flow filed becomes more complex and unstable with larger valve opening degree. To analyze the factors affecting the dynamic instability of flow field, the relationships between the opening degree and flow changes of inlet, outlet and throat are researched, also pressure changes of the valve and diaphragm are studied.

Abstract:For flying wing, high aspect ratio low Reynolds number aerodynamic layout is easy in a small angle of attack occurs under conditions of flow separation, it will bring significant nonlinear aerodynamic problems, while the impact of aeroelastic problem also can not be ignored. For this type of layout presents a radial basis function interpolation to establish the non-linear pressure coefficient distribution model. Established by radial basis function interpolation surface element on the angle of attack on the pressure coefficient derivative response surface, the pressure coefficient points and through infinite plate spline (IPS) method of interpolation of multiple iterations to achieve aerodynamic structure nonlinear aeroelastic analysis. The results show that the method for static aeroelastic analysis of the effectiveness of flexibility while accurately reflect bring aerodynamic efficiency loss and distortion effects on lift and drag.

Abstract:Monotonic tension tests and tension-tension fatigue tests combined with microscopic observation by scanning electron microscopy (SEM) were performed to investigate the fatigue behavior and life prediction of 2D C/SiC. The results show that C/SiC exhibits metal-similar ductile fracture behavior. The fatigue limit is about 85% of ultimate tensile strength(UTS), which indicates that C/SiC has excellent fatigue performance under room temperature. The tendency of the S-N curve of the notched specimen is consistent with the curve of the smooth specimen. But the curve of the notched specimen is higher than that of the smooth specimen, due to the notch insensitivity and notch blunted effect of composite materials. According to the test results, a fatigue prediction model based on the nominal stress is presented.

Abstract:For free turbine turboshaft engine with high thermodynamic parameters and high-bleed, a new turboshaft performance calculation model which considers bleed position and cooling air expansion work. The model of air bleeding in the middle of the compressor corrects the flow balance and power balance at the same time. The turbine cooling model considers the cooling air expansion work. The calculation results obtained by the new model are analyzed and compared with that of simple turbine bleed and cooling model, which proves that the new model can obtain the influence of the amount of bleeding and bleeding position to the performance of turboshaft engine. The new model are close to the true physical process of turboshaft engine, and can offer input to the air system.

Abstract:Requirement of performance calculation are provided for vertical section forecasting、vertical navigation parameter predicting and critical directing in flight management system,in order to manage and use flight performance data high efficiently, designing and creating airborne performance database are provided, furthermore,their data table structure and makeup are analysed,in addition,the course of building and loading airborne performance database document are analysed,and the value references are provided for design of flight management system and development engineering of airborne software.

Abstract:In order to estimate the disk weight quickly and accurately and to grasp the development trend of the disk structure correctly at the conceptual design stage of new aircraft engines, the model based on equal strength profile and corresponding program for evaluation of disk size and weight is set up. A turbofan engine disk is estimated with the program mentioned above. It is studied that the disk size and weight change with the radius of the center bore and the value of AN2 of the rotor blade. In addition, it is also studied that the disk size and weight change with the replacement of the rotor blade material at different radius of center bore and different values of AN2. The results show that there exists an optimum combination of disk stress and the radius of the center bore to get the minimum disk weight under limits of strength load and structure. With the new material of lower density for blade, the radius of the center bore of the disk will increase so that the rotor structure becomes bling, its weight dropped significantly.

Abstract:The system readiness level describes the whole technology state and level among the system investigation, which was an important assessment and analysis work in managing system. The matrix arithmetic was used to research the system readiness level of new helicopter, the result shown that, as technology readiness level of the most individual technology achieved anticipation, but there were some uncertainty and immature factors in the system. To improve the system readiness level, the bottleneck technology must be identified and broken, and the validation of bottleneck technology and other technology integration should be strengthened.