Abstract:With the rapid development of detecting technology and guided weapons ,and the change of political and economic environment at home and abroad, the development direction of the future bombers have changed greatly. The long-range strategic bomber is always one important tool of the country’s strategic deterrence and long-range strike, and its own stealth performance and plan track strategic call more and more attention. In this paper, by comparing the stealth performance of next generation stealth bombers developed by the United States and Russia and their faced threats, higher performance requirements of the new generation of stealth bombers had been proposed―full spectrum, all directional stealth technology, such as radar stealth、infrared stealth and radio frequency stealth. High stealth strategic bomber penetration measures were also summarize, including more advanced stealth technology, system support, the high altitude penetration, equipped with self-defense weapons.

Abstract:The Multimission Maritime Aircraft (MMA) is the major air force for anti-submarine warfare and Intelligence&Surveillance&Reconnaissance campaign on the sea. The cooperative engagement will be the most important mode of military campaign between the manned aircraft and the unmanned Aerial Vehicle (UAV). This paper put forward the concept of the cooperative engagement between the multimission maritime aircraft and the unmanned Aerial Vehicle, and then, the key technologies about the cooperative engagement between the multimission maritime aircraft and the unmanned Aerial Vehicle are discussed．The work in this paper plays an important role in the cooperative engagement development between the manned aircraft and the unmanned Aerial Vehicle.

Abstract:Zirconia-based ceramics for thermal barrier coatings is a key technology of aircraft engine. Since pure zirconia coating can not be applied directly, it is necessary to add stabilizers agent into it. According to the investigated results of stable zirconia-based ceramics for thermal barrier coatings doped with one component oxide, two component oxide and multicomponent oxide, the progress on zirconia-based ceramics for thermal barrier coatings made in phase stability, service temperature, thermal cycle life, thermal conductivity and coefficient of thermal expansion was systematically summarized in this paper. On this basis, the future research and development trend of zirconia-based ceramics for thermal barrier coatings are prospected.

Abstract:With the rapid development of science and technology, the complexity of national defense equipment is increasing, it is difficult to complete the security task reasonably and effectively by the military security capability. Therefore, this article gives an overview of commercial aircraft maintenance system, and provides recommendations for defense equipment support based on experience accumulated during commercial aircraft maintenance system construction from Civil-Military Integration point of view. The relevant technologies of civil aircraft maintenance system, i.e., the requirement analysis, health monitoring and management technology, maintenance strategy, support mode, and so on, are integrated into the field of defense equipment investigation, which are applied to perfect the technology and support mode of defense equipment.

Abstract:As one of the major damage modes of the aircraft fuel tank, hydrodynamic ram may cause a catastrophic destroy to the fuel tank structure. In order to analyze the hydrodynamic ram factors and effects systematically, this paper builds a validated model of the fuel tank by a full filled cube. Situations of different impact velocities, fragment masses, materials, shapes, incident angles, incident directions and various filling rates are studied. Parameters of the fragment speed decay, pressure inside the fuel tank and the deformation of the fuel tank wall are analyzed carefully. The results show that, the damage ability of the hydrodynamic ram will exacerbate with the increase of the impact velocity, mass and the filling rate. The shape of the fragment has a certain effect on the fluid pressure and the wall deformation. The incident angle and direction of the fragment will change its motion path in the fluid and then affect the hydrodynamic ram effect. Final in this paper, the least squares method is used to fit the deformation formula of the inlet and outlet wall of the simulation tank. The laws of the hydrodynamic ram of the fuel tank resulted from this paper can be used to assess the aircraft fuel system vulnerability and design reliable protection for the fuel tank.

Abstract:Aerodynamic shape is very important to UAV. It’s necessary to estimate UVA manufacturing deviation on its aerodynamic. The point cloud data of manufacturing shape of UAV can be measured by digital photogrammetric system. With the reference of nose, geometric deviation distribution statistics of the UAV can be obtained by the coordinate system of the point cloud model overlapping with the theoretical UAV model. Based on the cloud point, the three-dimensional model of manufacturing shape can be constructed by reverse modeling. The method that matches the test data can be obtained by comparing CFD calculation of the theoretical UAV with the wind tunnel test data while adjusting the grid and method of calculation. Aerodynamic data of the manufacturing shape can be obtained by using the same calculation method to compare with the aerodynamic force of theoretical shape. Result shows that aerodynamic characteristics deviation of manufacturing UAV can be quantitatively estimated.

Abstract:Fault Tree Analysis (FTA) is an important method of probabilistic safety assessment. The qualitative analysis of FTA can show the failure modes and weakness of system by using minimal cut set. And the quantitative analysis of FTA can calculate the probability of top event and the critical important indexes to rank of bottom events. In reliability analysis, the failure probability (i.e. the probability of top event) can be estimated by using coherent structural function, and then global sensitivity (also named important measure) analysis can be employed to determine the important input variables. Comparing the failure probability and important rank of basic events in probabilistic safety assessment with those of reliability estimation by using several FTAs of aircraft systems, we can find that the important rank of basic events will be different for the randomness of the basic events’ probabilities.

Abstract:The widespread use of UAV (Unmanned Aerial Vehicle) has made trajectory planning become a hot research area．Although there have been numerous UAV trajectory planning methods so far，it will be difficult to effectively apply in trajectory planning problems under complicated conditions on account of oversimplified planning models or inefficient planning methods．Therefore，an improved RRT-Connect (Rapidly-exploring Random Tree Connect) algorithm for this problem is put forward．Firstly，a mathematical model of UAV 3D trajectory planning problem is established．Then，when solving aforementioned model by adopting classical RRT-Connect algorithm，6 kinds of improved strategies for generating random nodes are put forward．Finally，the improved RRT-Connect algorithm are applied to UAV 3D trajectory planning problem under threat of thunderstorm．Compared with using classical RRT algorithm and classical RRT-Connect algorithm to solve the same problem，experiment results show that the improved RRT-Connect algorithm can efficiently generate feasible UAV trajectory．

Abstract:In the course of air combat, command and guide staff on my plane to conduct real-time command and guidance is an irreplaceable key element. In the actual air combat, the troops of both sides are not equal in normal circumstances. How to carry out the target allocation has become a problem to be solved urgently. In this paper, starting from the actual combat, the multi-aircraft and air combat command and guidance target allocation model was established. The Hungarian algorithm and the evolutionary Hungary algorithm were combined to study the multi-aircraft air combat command and guide the unbalanced target allocation. Finally, the simulation on the increase and reduction of the number of fighters are carried out. The simulation results show that this method can shorten the operation time and effectively ensure the overall command and guidance advantage of the target allocation scheme.

Abstract:Aiming at improving the conflict detection precision in a single classifier, a probabilistic conflict detection algorithm based on ensemble learning was proposed. Firstly, aircraft conflict model was established for the purpose of selecting flight datasets. Secondly, the current positions, speed vectors, look-ahead time, estimated turning time and turning angles were extracted as characteristic quantities which were inputted to train the basic classifiers, and a meta-datasets were obtained. Afterwards, support vector machine is used as the second-level classifier, the meta-datasets was regarded as new characteristic quantities which is used to train the stacking meta classifier. Lastly, the conflict probability was solved by the Sigmoid function mapping method. Simulation results have shown that this algorithm has a high accuracy for conflict detection and is suitable for turning flight.

Abstract:The research on the relationship between the terms of airworthiness of transport category aircraft and aeroengine is of great importance to the swift development of airworthiness certification of China. First of all, utilizing some data of the civil aviation regulations, we build the integrated data management system. Then, overlapping contents between CCAR-25 and CCAR-33 are summarized, and the relationship between them are analyzed. At last, the regulations for certain objects about fire-protection system and lubricating oil system are studied.

Abstract:In order to improve the evaluation efficiency of commercial aircraft maintenance ability, a PCA method is proposed to evaluate it. The principle of principal component analysis is introduced and the factors that affect the maintenance capability of commercial aircraft are summarized. The evaluation index system of commercial aircraft maintenance support system was established, and the different maintenance support schemes were evaluated by SPSS software to ensure the integrity of airworthiness of the aircraft. The results show that this method eliminates the influence of subjective factors on the evaluation. The obtained evaluation indexes can be used for the quantitative evaluation of the maintenance ability of commercial aircraft. The evaluation results can provide references for airlines and maintenance organizations.

Abstract:In view of the actual production situation of aviation manufacturing enterprise, in order to fulfill the multi-objective and real-time requirements of aviation parts in production scheduling, this paper proposd a new dynamic scheduling method, which included a weighting parameter adjustment model based on the technology of "exhaustive paired comparison" and a dispatching method based on improved Hungary algorithm. First, a flexible job shop dynamic scheduling mathematical model was bulit with the weighted sum of three factors, i.e., makespan, Scost of production and the energy consumption of production. Then, the weights were dynamically adjucted by using the technology of "exhaustive paired comparison" and thus the weights of each objective can be adjusted dynamically according to the the state of the workshop in real time. Finally, a improved Hungary algorithm was proposed to get the assignment scheme between Sworkpiece and machine to minimize the total objective. The simulation results show that the proposed dynamic scheduling method improvesSthe productivity of the aviation enterprise, reduce the cost of aviation enterprise production, and reduce the pollution to the environment and has a better comprehensive performance.

Abstract:The implementation of aviation special plan needs a lot of significant basic research projects to support. At present, aeronautical research management department mainly focuses on passive management in the process of project discovery, and fails to give full play to its role. A top-down process and mechanism on the major basic research projects is built to identify the major basic research projects to support the implementation of the national special plan effectively as well as taking project identify process with features into account. While relationships and functions are analyzed between the special planning departments in aeronautical field, the aeronautical scientific research management departments and the scientific research personnel involved in the identification of major basic research projects as well. And an aviation scientific research management department is used for example. The results show that based on the process of project identification, the discovery process and mechanism of major basic research projects in aviation field are completed and improved, and the role of aviation research management department is strengthened, and the effectiveness of project discovery is enhanced.

Abstract:Dynamic stall control is of great significance for enhancement of the airfoil aerodynamic characteristics. In the present study, the co-flow jet (CFJ) flow control method is numerically investigated to control the dynamic stall caused by the pitching airfoil. Two aspects regarding the CFJ implementation are studied: the effect of the CFJ channel on the dynamic stall characteristics when the jet is switched off and the effect of jet momentum coefficient on the dynamic stall control effectiveness when the CFJ is activated. Results show that the jet channel will significantly affect the aerodynamic characteristics in the attached flow regime during pitching up, but not have obvious influence on the aerodynamic characteristics in the massively separating regime during the pitching down process. When the jet is activated, the dynamic stall characteristics is significantly improved. The areas of the hysteresis lines are significantly reduced, and the lift is significantly increased, and drag is reduced. The peaks of the drag and moment are significantly reduced. Moreover, the negative damping existing in the moment coefficient hysteresis line of the baseline airfoil is removed, leading to a completely positive damping during the entire pitching cycle.

Abstract:Detailed research for wing aerodynamic characteristics of propeller slipstream at Low Reynolds number could contribute the mechanism study of low speed near space flow, and provide reliable aerodynamic results. The geometric model of single propeller with two-bladed is referred to a Solar-Powered UAV. High-quality structured grid is generated by ICEM software with two computational domains. Also, the grid application compatible boundary conditions employ sliding mesh method. It analyzes the development of propeller slipstream and unsteady aerodynamic characteristics of wing at Low Reynolds number propeller slipstream. Furthermore, it compares and analyzes the wing aerodynamic characteristics at different propeller positions. The results indicate that the propeller slipstream could significant change the surface pressure of the wing and the lift distribution along wingspan. Moreover, the results show that the propeller slipstream affects wing characteristic by changing the lift and drag. Meanwhile, the laminar separation bubble might be considerable prevented by the propeller slipstream.

Abstract:In this paper, the methods of reverse reconstruction and parametric modeling of the propeller are mainly studied. The torsion angle distribution and the pattern of the leaf-type stacking of the existing propeller model are optimized. In this paper, the propeller is taken as an example, and its reconstruction and parametric modeling are carried out. Numerical calculation techniques based on high-precision algorithms such as structured rotating grid and N-S equation are established and tested by experiments. Based on this, the CFD calculation of the propeller, the analysis and optimization of the blade twist angle and the stacking method are carried out to provide the help of the existing blade pull-down power

Abstract:FADS(Flush Air Data System) had been used in various aircraft, showing the advantages of less interference on flow field, thermal and stealth characteristics of the aircraft. Numerical computations based on Newton model and filtering algorithm were conducted to investigate the orifices distribution effects on Accuracies of FADS. Virtual flight path covering Mach number 4.3-15.79, height 25-70 kilometers was defined. Spherical nose was presented for FADS orifices arrangement. Results of clock angle effect, cone angle effect and asymmetric distribution effect were presented and analyzed. Computational results showed that increasing the number of pressure points along the circumference can improve the measurement Accuracies of the FADS system. However, there is a threshold value. When the number of pressure points is the same, increasing the cone angle can significantly improve the measurement Accuracies of FADS. The asymmetric distribution of the orifices has no effect on the measurement Accuracies.

Abstract:Hybridizing other fiber is an effective way to improve carbon fiber composite laminates toughness. To investigate the impact damaged behavior of hybrid composite laminates under bullet impact, a series of glass-carbon/epoxy and Kevlar-carbon/epoxy inter laminated hybrid plates are tested using steel projectile propelled by gas gun, and the damage zones and failure modes are inspected. Through the analysis of the experimental results, some understandings of the regularity are obtained as follows: compared with the common composite laminates, hybrid composite laminates could improve the impact damage resistance observably. Furthermore, the characteristic of hybrid layers, the matching performance of different materials, and mechanical properties of impacted side material all have obvious influence on impact damage of hybrid composite laminates.

Abstract:The ultra-high strength 300M steel is applied in aircraft landing gear. The tests of static tensile strength, three-point bending properties and Charpy impact properties were conducted. It reveals the mechanical properties and failure mechanism of electron beam deep seam welding of 300M steel. Macroscopic and microscopic analysis of typical specimens fracture after testing and fractography of weldment fracture surface have been investigated by SEM (Scanning Electron Microscope). Results indicate that both parent metal and weldment appear obvious tension plastic behavior, and there is little difference between stiffness and strength. However, the fracture strain and toughness of weldments becomes weaker compared with the parent metal. The bending strength of weldments is slightly lower than that of the parent metal, and the bending deformation and ductility decline. In Charpy impact test, both absorbed energy and fracture toughness of weldments are lower than parent metal. Thus the impact toughness of weldments decreases.

Abstract:The emission of engines has been a focused issue. With a piston engine as the object of study, Fire was used to establish a type of engine combustion chamber model from the perspective of combustion spray model; changes based on geometric parameters of existing combustion chamber were proposed; and simulation analysis was carried out under the new program; the nitrogen and oxygen compounds and carbon emissions between the old and new program were compared in a transient state. The results show that the emission of nitrogen oxides under the new combustion chamber structure is reduced by 23%, the carbon emission is reduced by 2.8%, and the overall emission is decreased. After installing the modified combustion chamber into the engine and maintaining the engine power and torque unchanged, a reduction in emission is clearly shown, which proved the design program is feasible.

Abstract:In a certain pressure difference and seal the surface of the mechanical surface morphology, the tight seal of the W-shaped seal ring sealing effect and tight seal with the flange area close to a reasonable choice of seal ring structure parameters can be enhanced by its flange seal Strict area to achieve the purpose of improving seal integrity. By finite element analysis software ABAQUS is used to simulate the influence of main structural parameters and pre-tightening amount on the sealing area of W-ring and flange, the following results were obtained: The larger external radius, pre-compression and wall thickness Parts and flange sealing area increases, the wall thickness and the outer radius of the seal ring in the flange contact area greater influence in the design process should be considered seal effect and stiffness flexibility, a reasonable choice of wall thickness and outer radius size.