Archive

  • 2020 Volume 37 Issue 6
    Published: 25 December 2020
      
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  • Research on The Design of A New Type Non-contact Sealing Structure for Dynamic and Static Frame of Altitude Test Platform
    2020, 37(6): 1-8.
    Abstract ( ) Download PDF ( )   Knowledge map   Save
    The joint of the static and dynamic frame of the aeroengine altitude test platform usually adopts a non-contact sealing structure. During the test, there is a pressure difference between the pipeline in the joint of the static and static frame and the external environment, which causes gas leakage here and affects the accuracy of the engine thrust test.In this paper, CFX simulation technology is used to carry out the design research on the connection and sealing structure parameters of the dynamic and static frame of the altitude test platform based on PTFE material.Through numerical simulation, the effects of the seal ring cross-sectional shape, the gap between the seal ring and the static frame, the pressure ratio, and the number of seal rings on the leakage of the seal structure were studied.The research shows that when the other structural parameters are controlled the same, and the sealing gap is reduced, the leakage of the sealing structure is significantly reduced, and the sealing effect of the trapezoidal section sealing ring is better than that of the D-shaped section sealing ring.When the other structural parameters are controlled unchanged and the pressure ratio of the inlet and outlet of the sealing structure is reduced, the leakage of the sealing structure decreases greatly. When the other structural parameters are controlled the same, and the value of the sealing ring is changed, the leakage of the sealing structure changes little.The research is of great significance to the design of the aeroengine altitude test platform dynamic and static frame connection seal structure and the improvement of the altitude test platform test thrust test accuracy.
  • Hygrothermal analysis of laminated plates based on exponential shear deformation theory
    2020, 37(6): 9-19.
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    In this paper, a composite laminates model for hygrothermal bending is developed based on the exponential shear deformation theory. The displacement field function of the model contains an exponential term that varies along the direction of the thickness direction, which can take into account the effects of lateral shear deformation and does not require the introduction of a shear correction factor. The governing equations and boundary conditions are derived based on the virtual work principle. Taking the four-side simply supported laminate as an example, the response of the stress and displacement of the laminate under hygrothermal is analyzed. The results of the example show that the model can accurately predict the displacement and stress response when the thermal load acts alone, especially compared with the classical laminate theory and the first-order shear deformation theory. When the wet and thermal loads work together, the predicted deflection of the model is greater than the classical plate theory and the first-order shear deformation theory, and the in-plane stress and transverse shear stress are also significantly different. In addition, although the mechanical load effect is not considered in the example in this paper, the model is universal and can be applied to the case of mechanical, thermal and wet loads.
  • Design and analysis of new concept vertical take-off and landing unmanned transport system
    2020, 37(6): 20-27.
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    In this paper, a new concept of vertical take-off and landing unmanned transport aircraft is presented. Secondly, based on the overall concept design, the six degree of freedom dynamic equation and kinematics equation of the unmanned transport aircraft are derived and established. Thirdly, based on the dynamic equation and kinematics equation and combined with the sliding mode control algorithm, a sliding mode controller of altitude and attitude of the unmanned transport aircraft is designed and a simulation control system is established. Finally, the simulation results show that the sliding mode control method can effectively control the yaw Angle and height of the UAV's roll Angle and pitch Angle accurately. Compared with the traditional PID method, the sliding mode control method has higher control accuracy and the control effect is consistent with the design goal.
  • Research on Information Interaction Platform Based on Dynamic Process
    2020, 37(6): 28-36.
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    Combined with the work characteristics of today's aviation manufacturing enterprises and based on the workflow of specific manufacturing enterprises, a dynamic online information interaction platform is designed to achieve real-time interaction of products, effective storage of data and strict monitoring of development progress. Through this information interaction platform, various departments, subsidiaries and third-party enterprises in the development can further coordinate and manage the definition of work content and delivery of work results between departments, improve development efficiency, shorten product development cycle, and then improve the company's products development capabilities.
  • Analysis of the influencing factors of plasma on the ignition characteristics of CH4-air
    2020, 37(6): 37-42.
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    In order to explore the effect of non-equilibrium plasma on the ignition delay time of methane, a chemical reaction kinetic model of the fuel was established, and the chemical reaction equation related to O3 was added on the basis of GRI-mech3.0 to prepare the plasma-assisted methane combustion reaction mechanism. Using zero-dimensional, homogeneous, fully mixed model and closed homogeneous model, the plasma-assisted methane combustion reaction process was numerically simulated, and the ignition temperature, pressure, and equivalent ratio were analyzed for the ignition delay time of methane/air/O3 mixture. The effect of non-equilibrium plasma on the ignition delay time of methane is obtained. The results show that: after adding O3, the ignition delay time is significantly reduced; at different pressures or different equivalence ratios, the logarithm of the ignition delay time of the methane/air/O3 mixture is linear with the ignition temperature; the ignition of the methane/air/O3 mixture The delay time gradually decreases with the increase of ignition temperature and pressure. Through sensitivity analysis, the chemical reaction mechanism of free radical generation of non-equilibrium plasma affecting the ignition of methane is revealed.
  • Calculation of supersonic gas-liquid two-phase cleaning nozzle
    2020, 37(6): 43-48.
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    In order to establish an efficient and reliable injection equipment calculation method and auxiliary spray nozzle design. The supersonic gas-liquid two-phase cleaning nozzle used to clean the surface of mechanical parts was calculated, and the flow in the core aerodynamic structure, Laval nozzle, was analyzed. Taking the two-phase flow composed of air and liquid particles as the research object, the Mac Cormack prediction-correction method is used to write the differential program in the engineering equation solver EES for numerical solution. The flow in the nozzle was calculated when the total inlet pressure was 0.5 ? 4.5MPa, the liquid phase flow was 0.005 ? 0.045 kg/s, and the liquid phase particle diameter was 10 ? 100μm. The effects of total inlet pressure, liquid phase flow and particle diameter on the two-phase flow were analyzed. The variation of flow parameters in the cleaning nozzle, the regulation of the working pressure of the cleaning nozzle and the temperature limitation are obtained.
  • An Improved Fault Diagnosis Method of DBN Aero-engine Lubricant Oil System
    2020, 37(6): 49-54.
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    Aero-engine fault diagnosis is one of the technical problems in the industry. In order to improve the effectiveness of the fault diagnosis of the aero-engine lubricating oil system, an improved fault diagnosis method of DBN aero-engine lubricat oil system is proposed, and the fault diagnosis technology of aero-engines is studied. First, pre-process the aero-engine lubricating system parameter data, and use DBN feature extraction capabilities and ELM rapid learning advantages to create a fault diagnosis model combining DBN and ELM. In order to reduce the impact of artificially adjusting the randomness of network parameters on the diagnosis results, particle swarm optimization is used to optimize the network parameters of DBN-ELM to obtain the optimal network structure and create an improved DBN fault diagnosis model. Finally, the experimental verification technology research on the created improved DBN fault diagnosis model is carried out. The results show that the proposed improved DBN fault diagnosis method can effectively improve the accuracy of aeroengine fault diagnosis, and the diagnosis effect is significantly better than DBN-ELM. Has a very good application prospect.
  • Human interaction recognition based on joint connection history maps and convolutional neural network
    2020, 37(6): 55-60.
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    The joint data can represent three-dimensional information of human motion accurately，and CNN can extract the deep features from image. Hence it is significant to combine them for human interaction recognition. Nowadays, most combining methods couldn’t make full use of the spatial position relationship and time sequence in the joint data, resulting in low recognition results. A new temporal and spatial feature extraction method of the joint data, joint connection history map is proposed. Firstly, each joint in the joint data is represented and connected according to the order of human skeleton. Then, the HSV color space is used to show the temporal relationship of joint data. A sequence of 3D joint data is transformed into 2D joint connection history map. Finally, it is sent to CNN to extract deeper features. The result shows that combining joint connection history map and CNN can identify human interaction exactly. And the recognition rate reaches 94.12% in the SBU Kinect interaction database, which proves the effectiveness of our algorithm.
  • Research on the impact of executive compensation on the dynamic adjustment of capital structure from the perspective of corporate governance
    2020, 37(6): 61-71.
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    Based on the dynamic tradeoff theory, agency theory and the optimal contract theory, selects 2009-2017 a-share listed companies in our country as samples, using the standard partial adjustment model, through the SYS - GMM method to test the relationship between executive compensation and capital structure adjustment speed, And the difference between the level of corporate governance and the nature of property rights, the relationship between executive compensation and the speed of capital structure adjustment.The study found that, on the whole, the higher the executive compensation, the faster the capital structure adjustment, which was only significant in private enterprises.The higher the degree of ownership concentration, the higher the proportion of managers who are not concurrently the chairman of the board and the independent directors in the board of directors, the better the incentive effect of executive compensation, the more obvious the effect of reducing agency costs, and the faster the capital structure adjustment.This shows that the improvement of corporate governance mechanism can effectively improve the incentive effect of executive compensation to promote the speed of capital structure adjustment. In particular, state-owned enterprises should strengthen the supervision of senior executives and accelerate the optimization of enterprise capital structure.
  • Visualization Analysis of International Employee Feedback Seeking Behavior Research Based on Knowledge Mapping
    2020, 37(6): 72-82.
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    Accurately grasping the status quo, hot spots and development frontiers of employee feedback seeking behavior worldwide, The knowledge maps of national cooperation network, institutional cooperation network and author cooperation network are generated, and the main sources of current feedback seeking behavior research are analyzed. Through clustering key words and their evolution process and cited literature hotspots, the process of research hotspots and future development frontiers are grasped. The paper conducts a visual knowledge map analysis of 979 related literatures of feedback seeking behaviorin the SSCI by using CiteSpace software in 20 years.The research shows that the overall research strength in this field is on the rise year by year. China’s influence in the field is growing; Chinese scholar Qian jing is producing the most articles. The most influential institution is Maastricht Univ of the Netherlands; The cooperation network between authors is not intensive. According to the characteristics of hotspot keywords and frequency burst history, feedback seeking behavior research can be divided into three periods;The research on employee feedback seeking behavior focuses on four hot perspectives: employee personality, leader style, organizational environment and feedback seeking performance.
  • Optimization method of flight sequencing under the condition of single runway continuous departure
    2020, 37(6): 83-90.
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    In recent years, due to the shortage of airspace resources, flights are subject to flow control from time to time, resulting in the dissatisfaction of passengers and the increase of operating costs of airlines. In this paper, under the background of the occurrence of flow control in the collaborative flow management system, aiming at the sequencing problem of continuous departure flights at a single runway airport, a method is designed to first sort the estimated over-point time of controlled flights, and then to minimize the total time and the difference sum of the flight off-wheel block time, NSGAII fast non-dominant sorting algorithm is used to reorder the whole of the flight set at the time of expected flight withdrawal. Compared with the FCFS optimization algorithm, the optimization results shorten the total time of the target gear shift by 26%, and reduce the difference and 869 minutes. The departure time was then calculated 74 minutes earlier.This method can alleviate the problem of capacity imbalance, prevent the occurrence of air route congestion, improve the operation efficiency of airports and airlines to save costs has positive significance.