Abstract:The intensivenoise of carrier-based aircraft is a serious threat to the healthof carrier deck staff and people in communitiessurrounding the naval base. Noise reduction is one of the key research projectsamong the technologies of carrier-based aircraft. Beginning with the noise problem of carrier-based aircraftand its effects and risks, this paper points out the core source of noise, engine jet noise, summaries the new advances of jet noise suppression technologies, and raises the idea that multiple methods ought to be comprehended to solve the noise problem of carrier-based aircraft.

Abstract:A comprehensive introduction was taken on the research and application of composite shaft both inland and abroad., and the effects on fatigue load, damage tolerance and vibration caused by layer designs were analyzed. Brief Principal on composite shaft design was summarized. Some suggestions on the research of composite shaft in the future were put forward at last.

Abstract:In order to provide technical parameters choosing refference to performance as well as size amd weight computations of turboshaft engines, the technical parameters of ten typical types of foreign turboshaft engines were collected. Then, the models and corresponding programs for performance calculations and evaluations of size and weight of turboshaft engines were set up. The technical parameters were collected of ten foreign typical turboshaft engines from 1 to 4 generations, which were evaluated with the programs metioned above so that the level and developing trends of these parameters were obtained. Then, the technical parameters were evaluated of the advanced turboshaft engine of next generation. Based on the developing trends of the technical parameters, it was studied what the main dynamic, structural and strength parameters would affect the turboshaft engine performances, which helped to provide evidences of turboshaft engine integration design.

Abstract:Weight is one of the most important performances for the aviation productions. The most effective approach to weight saving is developing the lower density material. Introduce advanced Al-Li (Aluminum-Lithium) alloy with lower density, higher tensile strength, better damage tolerance etc. Compare to conventional aluminum alloys and trade-off study with advanced composites. Analysis the properties of 3rd-generation Al-Li alloy and the applications on advanced aircraft. Provide the proposals of applications in civil program. The research can be the reference of materials selection and weight saving for commercial aircraft, and benefit extending applications of Al-Li alloy.

Abstract:Wing-in-ground effect of NACA0012 at angle of attack of 18? was tested in a model wind tunnel. The velocity fluctuations in wake near the trailing edge were captured by 3D CTA. Unsteady flow of wing-in-ground effect in different flight height was analyzed based on the test results.The aim is to provide a reliable basis for the aerodynamic characteristics and control of unsteady flow of wing-in-ground effect at a high attack angle. It is shown that vortices near trailing edge of wing in ground effect at high angle of attack are shifted backwards in ground effect; with decrease of flight height, both the frequency and the

Abstract:Peel stress causing by secondary bending in composite-metal adhesively single lap joints will decrease strength of the joints. In this article it analyzes the effect of different ply orientation angle, different ply stacking sequence and chamfering to secondary bending of bonded single lap joints with finite element method. It also analyzes the relation between secondary bending and peel stress, bending stiffness. It discovers that the bending stiffness affects the peel stress; the bigger bending stiffness is, the smaller secondary bending is; the chamfering helps to reduce secondary bending.

Abstract:The multiple 3D cracks initiated from the multiple fastener holes frequently occur in aircraft structural components. The fatigue crack growth life prediction of the situation is one of the major concerns and the technically tough work in the multiple-site damage assessment. Our paper investigates the methodology of fatigue crack growth prediction for multiple 3D cracks starting from multiple countersunk fastener holes. An efficient numerical method was proposed in which the computer code was made using the parametrical language of the finite element analysis package. The fast finite element modeling and automatic mesh regeneration, together with a fast cumulative damage technique of fatigue crack growth, were conducted to achieve the life-span numerical simulation for multiple 3D crack growth. The net-section yielding was considered as the criterion to terminate the fatigue life prediction. Two scenarios of a pair of initial asymmetric corner cracks initiated from both sides of a countersunk fastener hole were taken as example problems and analyzed throughout their fatigue crack growth lives. The simulation results agree well with the experimental results.

Abstract:The use of foam sandwich in wing structure can reduce the weight of structure. So the optimization of foam sandwich composite is important. An optimization algorithm is design to optimize angle of ply and thickness of plies simultaneously based on genetic algorithm. In the article the region division technique and the floating-point coded are taken in the previous optimization design. The optimization of the ply design of the foam sandwich skin of the composite wing structure is accomplished through the previous optimization method. The optimal result is that the weight is reduced by 38.2%.The result shows that the weight will be reduced by the optimal method. There are certain values for making use of foam sandwich structural.

Abstract:In this paper, a three-dimensional progressive damage model of bonded-bolted joints was established with ABAQUS and by employing cohesive zone method to simulate the behavior of adhesive, a thorough analysis of the structural strength of bonded-bolted hybrid and the factors affecting it is presented. Firstly, the structural strength of bonded-bolted hybrid, bonded joints and bolted joints were analyzed comparatively and a detailed explanation was made to the carrying principle and stress distribution in bonding area of bonded-bolted hybrid and bonded joints, demonstrating that bonded-bolted hybrid is the best among the three in terms of structural strength. Then, the influence of bolt head type and width to diameter ratio to the structural strength and damage type to bonded-bolted hybrid structure was discussed, putting forward the best bolt head type and width to diameter ratio to better the structural strength.

Abstract:Composite laminate has enjoyed a wide application in aerospace structures, thus the reinforcement of the cutout has always been concerned. Composite laminate with large opening under three different load cases: tension, shear and compress were investigated. The optimization design of different types of reinforcement with different materials was also conducted. The parameters of reinforced structure were optimized to satisfy the objective weight function, and the multi-level optimization method was adopted during the optimization process. The weight characteristics of reinforced structure were also compared and analyzed. The results show that under different load cases, compared with bolt connection reinforcement and co-curing reinforcement, intercalation reinforcement is better with the minimum weight increase.

Abstract:The paper described a work that forced on the analysis the ground wind acting on the new generation launch vehicle during the vertical state. The ground wind load acting on the launch vehicle was divided into four different ground wind loads according to the causes of wind load and the effects of directions. In order to obtain the response of launch vehicle under the effects of ground wind loads, the random analysis function of MSC.Patran/Nastran was used to describe the launch vehicle 's displacement response when the ground wind speed is at 4~20m/s. The results indicated that the launch vehicle's displacement response increases with the incensement of ground wind speed. and the shedding vortex load becomes the dominant reason that result in the carrier rocket's displacement response with the increase of ground wind speed.

Abstract:In order to simulate the transonic and subsonic modes using the scramjet engine performance computational model established by this research group which based on the integral equations, the residual equation is established by critical mass flow method with a independent variable of static pressure at the export of isolator in this paper. This equation which expresses the extent of thermal chock is iterated by Newton-Raphson method to simulate the working condition of the transonic and subsonic modes on which there is a critical cross-section and no thermal chocks, viz. a thermal throat, in the combustor. The results show that the distribution of one-dimension parameters with a thermal throat in the combustor can be simulated with this method. Meanwhile, this method is of high accuracy, fast computing speed and good convergence. It contributes much to the solving of the scramjet engine performance computational model.

Abstract:Numerical simulation method of high bypass ratio separate flow exhaust system is adopted and satisfactory result has obtained. Based on the initial exhaust system, the influence of the different outlet area of external and internal bypass, the different length of the outer casing and tail cone on the aerodynamic performance have been investigated. Through analysis and investigation, this paper provides the working foundation to the design of the similar exhaust systems. The results show the existence of an optimal available pressure ratio of external bypass which makes thrust coefficient maximum, but the external bypass will be at under-expanded state when the pressure ratio is adopted. Its design is different from the single channel nozzle. Secondly, there is an optimal outlet area of nozzle which makes thrust coefficient maximum, but the nozzle will be at over-expanded state when the outlet area is adopted. It mainly depends on the pressure distribution of the outer casing and tail cone. Thirdly, the length of outer casing also influences the performance of the exhaust system.

Abstract:Aircraft development is a huge systematic engineering, Part dataset of traditional aircraft product structure including mass documents such as 2D drawings, 3D models, temporary change sheets and which change frequently, in the same time, it also costs manufacture and maintenance department a lot of work to reconstruct engineering data which easily to be mistaken, so the management of the product data is so complex, hard, and lower efficiency. Refer to the experiences of other international leading aircraft company, this paper develops a simplified product structure management solution based on module theory and three dimension design method. This paper takes an certain type aircraft for example, emphatically analyses the organized mode of product structure, the composition of engineering dataset, the rules for data change, to make sure the configuration data to be convenient and exactly, and this product structure management solution also conforms to the full digital trend of aircraft product development in the future.

Abstract:The correlation-based transition model was originally developed by Langtry and Menter for use with the two-equation k-w SST turbulence model. DES methods have lower eddy viscosity than RANS method in its LES zone outside the boundary layer, this will affect performance of transition model. The behavior of transition model implemented in DES and DDES model was investigated. The numerical test on flat plate show that DDES method can delay the transition, and in DES method, transition was suppressed by the over-reduced eddy viscosity. This indicated that DDES method is more suitable for implementing of transition model than DES method and recalibration of the transition model is required.

Abstract:The gap flow parameters of multi-element airfoil have significant effect on its lift characteristics. The major method to improve the aerodynamic performance of the airfoil is changed the gap flow parameters by changed the airfoil shape, the combinations of gap geometric parameters and active / passive controlled the gap flow. Using wind tunnel experimental method, the authors compared the lift characteristics of a multi-element airfoil under conditions of different flap acoustic excitation modes for the purpose of exploring a new way to improve the effectiveness of high-lift configuration. The experiments were conducted in NF-3 wind tunnel. Acoustic excitations of disturbances are four modes including single point, single row, multi-slice and the M-type combination. The results showed that, within the range of this research, the weak disturbances of the acoustic excitation can indeed change the lift coefficient of multi-element airfoil. And disturbances manner corresponding to the lift coefficient variation of the airfoil is also inconsistent. The lift coefficient of airfoil was increased by M-type combination acoustic excitation when single point acoustic excitation reduced it.This paper confirms that the designers should study the dynamic press characteristics of flow near the flap.

Abstract:The altitude controlling for aerial tow target of flight at lower-altitude can not adopt orientation-control by reason of moderate cost. This paper considers the problem of invariableness altitude flight for aerial tow target by one-dimensional altitude control (non-orientation-control). The aerial tow target for invariableness altitude flight is provided with higher-stability, and it has elevators that is used to produce motion up or down by approximately derect lift. In this paper, it is described dynamically modeling and automatically controlling the motion of invariableness altitude flight. The aerodynamics characteristic of aerial tow target is analyzed, and some typical results in a digital computer simulation are provided. The results show that the aerial tow target system can control flight altitude and achieve invariableness altitude flight.

Abstract:In this paper, an approximation method is presented for calculating the wing load envelope and using to size the wing box in wing strength primary design phase. It is found that the triangle weight load distribution is better than other distributions in simulating the wing weight. Furthermore, this paper investigates the characters of critical over loading and centralized loads for large civil aircrafts. An approximation method for calculating the wing load envelope of bending moment and shear force in flight is proposed by combining the Schrenk lift distribution and triangle weight distribution. Then, the proposed method is validated by wind tunnel data of wing shear forces and bending moments.

Abstract:Investigation for wavelet denoising based on digital speckle correlation method(DSCM) is introduced in this paper. In order to improve the accuracy of deformation measurement with the digital speckle correlation method in composites, digital speckle technology is combined with wavelet denoising technology, and threshold denoising method is used to threshold quantification for wavelet coefficients. In order to demonstrate the denoising method applying to deformation measurement of composites using digital speckle correlation method, this paper performs the tensile test of composites. And this wavelet denoising method is used to results of the measurement with digital speckle correlation method. The test reveals an agreement with measurement results of the extensometer. The wavelet denoising method used in the digital speckle correlation method to eliminate the noises is better.

Abstract:Based on the discrete data/accumulation theory of rapid prototyping technology, a method for stealth model design was given to resolve the problem of weight in big-scale stealth model design. Metal model was designed and manufactured by using some discrete frames and cumulate surface for stealth test. The test shows that the model met stealth test requirement, while the model was lighter than 50kg which had characteristic dimension about 5m. This method could gain a light model, and improve precision of radar stealth test and reduce test cost.

Abstract:The supercooled large drop regulations would increase the level of safety during flight in icing and have a certain impact on ice detection system design. Appendix O Supercooled large drop icing conditions is summarized, the brief analysis of appendix O part I-meteorology is performed, the effect of FAR25.1420 supercooled large drop icing conditions on ice detection system design is analyzed, the ice detection methods complying with related requirements are provided in this paper. If certification for flight in icing conditions is sought now, it is appropriate for an airplane with a maximum takeoff weight less than 60, 000 pounds or with reversible flight controls to certificate in accordance with FAR25.1420(a)(1). In addition, a proposal of ice detection system complying with FAR25.1420 is presented.