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  • Articles  (9)
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  • International Journal of Aerospace Engineering  (2)
  • 97414
  • Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics  (9)
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  • Articles  (9)
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  • Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics  (9)
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  • 1
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    New Method for Analyzing the Flutter Stability of Hingeless Blades with Advanced Geometric Configurations in Hovering (2020)
    Hindawi
    Details
    Publication Date: 2020-02-17
    Description: A new method used to analyze the aeroelastic stability of a helicopter hingeless blade in hovering has been developed, which is especially suitable for a blade with advanced geometric configuration. This method uses a modified doublet-lattice method (MDLM) and a 3-D finite element (FE) model for building the aeroelastic equation of a blade in hovering. Thereafter, the flutter solution of the equation is calculated by the V-g method, assuming blade motions to be small perturbations about the steady equilibrium deflection. The MDLM, which is suitable to calculate the unsteady aerodynamic force of nonplanar rotor blade in hovering, is developed from the doublet-lattice method (DLM). The structural analysis tool is the commercial software ANSYS. The comparisons of the obtained results against those in the literatures show the capabilities of the MDLM and the method of structural analysis. The flutter stabilities of swept tip blades with different aspect ratios are analyzed using the new method developed in this work and the usual method on the basis of the unsteady strip theory and beam model. It shows that considerable differences appear in the flutter rotational velocities with the decrease of the aspect ratio. The flutter rotational velocities obtained by the present method are evidently lower than those obtained by the usual method.
    Print ISSN: 1687-5966
    Electronic ISSN: 1687-5974
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Published by Hindawi
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  • 2
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    Precise Orbit Determination of BDS MEO Satellites Based on Satellite TT&C Stations (2016)
    Hindawi
    Details
    Publication Date: 2016-02-16
    Description: A novel method, which is based on the triple-frequency combination and Space-Based Telemetry, Tracking, and Command (STT&C) stations, is proposed in this paper. Considering BeiDou Navigation Satellite System (BDS) Geostationary Orbit (GEO) and Inclined Geostationary Orbit (IGSO) satellites as the STT&C facilities, firstly, we presented the BDS Medium Earth Orbit (MEO) satellites’ precise orbit determination scheme based on triple-frequency combination. Then, we gave the sufficient and necessary conditions about the visibility and the coverage rate calculation model of STT&C to BDS MEO satellite. And then we deduced the model of BDS MEO satellites precise orbit determination based on triple-frequency combination observations. At last, we designed the simulation calculation. The simulation results show that orbit determination of BDS MEO satellite based on STT&C station can be realized at all times. And most of the simulation period time, under the condition of the dm level orbit determination for GEO/IGSO satellites, the position accuracy of the relative orbit determination is better than 4 m, the horizontal accuracy of the relative orbit determination is within 2.5 m, and the vertical accuracy of the relative orbit determination is less than 3.5 m.
    Print ISSN: 1687-5966
    Electronic ISSN: 1687-5974
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
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  • 3
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    Adaptive Differential Thrust Methodology for Lateral/Directional Stability of an Aircraft with a Completely Damaged Vertical Stabilizer (2018)
    Hindawi
    Details
    Publication Date: 2018-03-06
    Description: This paper investigates the utilization of differential thrust to help a commercial aircraft with a damaged vertical stabilizer in order to regain its lateral/directional stability. In the event of an aircraft losing its vertical stabilizer, the consequential loss of the lateral/directional stability and control is likely to cause a fatal crash. In this paper, an aircraft with a completely damaged vertical stabilizer is investigated, and a unique differential thrust-based adaptive control approach is proposed to achieve a stable flight envelope. The propulsion dynamics of the aircraft is modeled as a system of differential equations with engine time constant and time delay terms to study the engine response time with respect to a differential thrust input. The proposed differential thrust control module is then presented to map the rudder input to differential thrust input. Model reference adaptive control based on the Lyapunov stability approach is implemented to test the ability of the damaged aircraft to track the model aircraft’s (reference) response in an extreme scenario. Investigation results demonstrate successful application of such differential thrust approach to regain lateral/directional stability of a damaged aircraft with no vertical stabilizer. Finally, the conducted robustness and uncertainty analysis results conclude that the stability and performance of the damaged aircraft remain within desirable limits and demonstrate a safe flight mission through the proposed adaptive control methodology.
    Print ISSN: 1687-5966
    Electronic ISSN: 1687-5974
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Published by Hindawi
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  • 4
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    Precise Orbit Determination of BDS MEO Satellites Based on Satellite TT&C Stations (2016)
    Hindawi
    Details
    Publication Date: 2016-01-01
    Description: A novel method, which is based on the triple-frequency combination and Space-Based Telemetry, Tracking, and Command (STT&C) stations, is proposed in this paper. Considering BeiDou Navigation Satellite System (BDS) Geostationary Orbit (GEO) and Inclined Geostationary Orbit (IGSO) satellites as the STT&C facilities, firstly, we presented the BDS Medium Earth Orbit (MEO) satellites’ precise orbit determination scheme based on triple-frequency combination. Then, we gave the sufficient and necessary conditions about the visibility and the coverage rate calculation model of STT&C to BDS MEO satellite. And then we deduced the model of BDS MEO satellites precise orbit determination based on triple-frequency combination observations. At last, we designed the simulation calculation. The simulation results show that orbit determination of BDS MEO satellite based on STT&C station can be realized at all times. And most of the simulation period time, under the condition of the dm level orbit determination for GEO/IGSO satellites, the position accuracy of the relative orbit determination is better than 4 m, the horizontal accuracy of the relative orbit determination is within 2.5 m, and the vertical accuracy of the relative orbit determination is less than 3.5 m.
    Print ISSN: 1687-5966
    Electronic ISSN: 1687-5974
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
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  • 5
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    Experimental Study of Torque Using a Small Scoop on the Lunar Surface (2016)
    Hindawi
    Details
    Publication Date: 2016-01-01
    Description: Chinese missions to the moon are planned to sample the regolith and return it to the earth. Microscale excavators may be good candidates for these missions, as they would significantly reduce the launch mass. Thus, it is necessary to research the interaction between the scoop and the regolith being sampled. We present the development of a simple apparatus to measure excavation torque. All tests were conducted using TYII-2 regolith simulant with gravels. The test results show that, under loose regolith conditions, the penetrating angle and the bulk density had a great influence on the excavation torque, while the rotating speed had little effect. However, when the bulk density was compact, the rotating speed did influence the excavation torque. The excavation torque increased sharply when the scoop encountered the gravels; actually, some of the parameters will influence the value of the torque such as the diameter, quantity, and position and inbuilt depth of the gravels. When the excavation torque sharply increases, the operation should be immediately stopped and checked.
    Print ISSN: 1687-5966
    Electronic ISSN: 1687-5974
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Published by Hindawi
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  • 6
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    A Study on the Separation Length of Shock Wave/Turbulent Boundary Layer Interaction (2019)
    Hindawi
    Details
    Publication Date: 2019-10-20
    Description: The separation length of shock wave/boundary layer interaction (SWBLI) was studied by a numerical method, which was validated by experimental results. The computational domain was two-dimensional (2-D). The flow field was an incident oblique shock interacting with a turbulent boundary layer on a flat adiabatic plate. According to the simulation data, the dependency of the separation length on the relevant flow parameters, such as the incident shock strength, Reynolds number, and Mach number, was analyzed in the range of 2≤M≤7. Based on the relations with the flow parameters, two models of the separation length at low and high Mach numbers were proposed, respectively, which can be used to predict the extent of the separation in the SWBLI.
    Print ISSN: 1687-5966
    Electronic ISSN: 1687-5974
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
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  • 7
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    Adaptive Differential Thrust Methodology for Lateral/Directional Stability of an Aircraft with a Completely Damaged Vertical Stabilizer (2018)
    Hindawi
    Details
    Publication Date: 2018-01-01
    Description: This paper investigates the utilization of differential thrust to help a commercial aircraft with a damaged vertical stabilizer in order to regain its lateral/directional stability. In the event of an aircraft losing its vertical stabilizer, the consequential loss of the lateral/directional stability and control is likely to cause a fatal crash. In this paper, an aircraft with a completely damaged vertical stabilizer is investigated, and a unique differential thrust-based adaptive control approach is proposed to achieve a stable flight envelope. The propulsion dynamics of the aircraft is modeled as a system of differential equations with engine time constant and time delay terms to study the engine response time with respect to a differential thrust input. The proposed differential thrust control module is then presented to map the rudder input to differential thrust input. Model reference adaptive control based on the Lyapunov stability approach is implemented to test the ability of the damaged aircraft to track the model aircraft’s (reference) response in an extreme scenario. Investigation results demonstrate successful application of such differential thrust approach to regain lateral/directional stability of a damaged aircraft with no vertical stabilizer. Finally, the conducted robustness and uncertainty analysis results conclude that the stability and performance of the damaged aircraft remain within desirable limits and demonstrate a safe flight mission through the proposed adaptive control methodology.
    Print ISSN: 1687-5966
    Electronic ISSN: 1687-5974
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Published by Hindawi
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  • 8
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    Inflatable Leading Edge-Based Dynamic Stall Control considering Fluid-Structure Interaction (2020)
    Hindawi
    Details
    Publication Date: 2020-02-20
    Description: The inflatable leading edge (ILE) is explored as a dynamic stall control concept. A fluid-structure interaction (FSI) numerical method for the elastic membrane structure is constructed based on unsteady Reynolds-averaged Navier-Stokes (URANS) and a mass-spring-damper (MSD) structural dynamic model. Radial basis function- (RBF-) based mesh deformation algorithm and Laplacian and optimization-based mesh smoothing algorithm are adopted in flowfield simulations to achieve the pitching oscillation of the airfoil and to ensure the mesh quality. An airfoil is considered at a freestream Mach number of 0.3 and chord-based Reynolds number of 3.92×106. The airfoil is pitched about its quarter-chord axis at a sinusoidal motion. The numerical results indicate that the ILE can change the radius of curvature of the airfoil leading edge, which could reduce the streamwise adverse pressure gradient and suppress the formation of dynamic stall vortex (DSV). Although the maximum lift coefficient of the airfoil is slightly reduced during the control process, the maximum drag and pitching moment coefficients of the airfoil are greatly reduced by up to 66% and 75.2%, respectively. The relative position of the ILE has a significant influence on its control effect. The control laws of inflation and deflation also affect the control ability of the ILE.
    Print ISSN: 1687-5966
    Electronic ISSN: 1687-5974
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
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  • 9
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    Allocation Optimization Strategy for High-Precision Control of Picosatellites and Nanosatellites (2018)
    Hindawi
    Details
    Publication Date: 2018-07-15
    Description: The high-precision control of picosatellites and nanosatellites has always plagued the astronautics field. Aiming to change the status quo of the actuators not being able to meet the high-precision attitude control of picosatellites and nanosatellites, this article formulates a control allocation strategy for picosatellites and nanosatellites using the solid propellant microthruster array (SPMA). To solve the problem of the diversity and complexity of ignition combinations brought about by the high integration of the SPMA, the energy consumption factor of the optimal allocation is established, and the relationships of the array’s energy consumption factor, the control accuracy, the number, and the ignition combinations of the thruster array are deduced. The optimization objective is introduced by Sherman-Morrison formula and singular value decomposition. Thus, the energy consumption problem is transformed into an integer programming problem, acquiring the control allocation strategy and the optimal thruster energy. Simulation results show that the proposed algorithm can effectively reduce the thrust energy consumption and improve the precision control, demonstrating the feasibility and efficiency of the proposed algorithm for picosatellites and nanosatellites.
    Print ISSN: 1687-5966
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    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
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