scholarly journals Modeling, Simulation, and Cruise Characteristics of Wingtip-Jointed Composite Aircraft

2020 ◽  
Vol 10 (23) ◽  
pp. 8763
Author(s):  
Dongxu Liu ◽  
Changchuan Xie ◽  
Guanxin Hong ◽  
Chao An
Keyword(s):  
Simulation Method ◽  
Rigid Bodies ◽  
Characteristic Parameters ◽  
Optimization Analysis ◽  
Modeling Simulation ◽  
Multibody Dynamic ◽  
Aerodynamic Database ◽  
Aircraft System ◽  
Drag Ratio ◽  
Mathematical Derivation

In this paper, multibody dynamic modeling and a simulation method for the wingtip-jointing process of a new-concept composite aircraft system are investigated. When the wingtips of two aircraft are jointed, the resultant wingtip-jointed aircraft is regarded as variable-geometry multiple rigid bodies, and a seven-degree-of-freedom non-linear dynamic model is established by mathematical derivation. The slip-meshing method is adopted to analyze the unsteady aerodynamic influence. We also present specific aerodynamic database acquisition methods under the quasi-steady assumption. Based on this, the simulation results indicate that the longitudinal and lateral movements are highly jointed and complex. A new composite aircraft system is investigated, in order to meet the balance requirement. With the lift–drag ratio (K) considered, the piecewise cubic Hermite interpolation (PCHIP) method, with a sufficient sample size, was utilized to help the cruise strategy optimization analysis under fixed altitude and speed conditions. Meanwhile, distribution of cruise characteristics with different sampling values of composite flight characteristic parameters were also analyzed. The research results can be used as a reference for new-concept composite aircraft model establishment, simulation, and multibody dynamic characteristic investigation.

scholarly journals An estimation method for the fuel burn and other performance characteristics of civil transport aircraft during cruise: part 2, determining the aircraft’s characteristic parameters

2020 ◽  
Vol 125 (1284) ◽  
pp. 296-340
Author(s):  
D.I.A. Poll ◽  
U. Schumann
Keyword(s):  
Estimation Method ◽  
Accurate Method ◽  
Characteristic Parameters ◽  
Transport Aircraft ◽  
The Public ◽  
Engine Thrust ◽  
Fuel Burn ◽  
Burn Rate ◽  
Drag Ratio ◽  
Independent Parameters

ABSTRACTA simple yet physically comprehensive and accurate method for the estimation of the cruise fuel burn rate of turbofan powered transport aircraft operating in a general atmosphere was developed in part 1. The method is built on previously published work showing that suitable normalisation reduces the governing relations to a set of near-universal curves. However, to apply the method to a specific aircraft, values must be assigned to six independent parameters and the more accurate these values are the more accurate the estimates will be. Unfortunately, some of these parameters rarely appear in the public domain. Consequently, a scheme for their estimation is developed herein using basic aerodynamic theory and data correlations. In addition, the basic method is extended to provide estimates for cruise lift-to-drag ratio, engine thrust and engine overall efficiency. This step requires the introduction of two more independent parameters, increasing the total number from six to eight. An error estimate and sensitivity analysis indicates that, in the aircraft’s normal operating range and using the present results, estimates of fuel burn rate are expected to be in error by no more than 5% in the majority of cases. Initial estimates of the characteristic parameters have been generated for 53 aircraft types and engine combinations and a table is provided.

scholarly journals Shock Mechanism Analysis and Simulation of High-Power Hydraulic Shock Wave Simulator

2017 ◽  
Vol 2017 ◽  
pp. 1-10 ◽  
Author(s):  
Xiaoqiu Xu ◽  
Han Tao ◽  
Junwei Han
Keyword(s):  
Shock Wave ◽  
High Power ◽  
Structure Optimization ◽  
Simulation Method ◽  
Mechanism Analysis ◽  
Hydraulic Shock ◽  
Characteristic Parameters ◽  
Software Simulation ◽  
Shock Mechanism ◽  
Shock Characteristic

The simulation of regular shock wave (e.g., half-sine) can be achieved by the traditional rubber shock simulator, but the practical high-power shock wave characterized by steep prepeak and gentle postpeak is hard to be realized by the same. To tackle this disadvantage, a novel high-power hydraulic shock wave simulator based on the live firing muzzle shock principle was proposed in the current work. The influence of the typical shock characteristic parameters on the shock force wave was investigated via both theoretical deduction and software simulation. According to the obtained data compared with the results, in fact, it can be concluded that the developed hydraulic shock wave simulator can be applied to simulate the real condition of the shocking system. Further, the similarity evaluation of shock wave simulation was achieved based on the curvature distance, and the results stated that the simulation method was reasonable and the structural optimization based on software simulation is also beneficial to the increase of efficiency. Finally, the combination of theoretical analysis and simulation for the development of artillery recoil tester is a comprehensive approach in the design and structure optimization of the recoil system.

scholarly journals A Simulation Model for Computing the Loads Generated at Landing Site During Helicopter Take-Off or Landing Operation

2019 ◽  
Vol 2019 (2) ◽  
pp. 59-75
Author(s):  
Jarosław Stanisławski
Keyword(s):  
Equations Of Motion ◽  
Landing Site ◽  
Simulation Method ◽  
Rigid Bodies ◽  
Landing Gear ◽  
Rotor Blades ◽  
Wind Gust ◽  
The Galerkin Method ◽  
Lumped Masses ◽  
And Control

Summary The paper presents simulation method and results of calculations determining behavior of helicopter and landing site loads which are generated during phase of the helicopter take-off and landing. For helicopter with whirling rotor standing on ground or touching it, the loads of landing gear depend on the parameters of helicopter movement, occurrence of wind gusts and control of pitch angle of the rotor blades. The considered model of helicopter consists of the fuselage and main transmission treated as rigid bodies connected with elastic elements. The fuselage is supported by landing gear modeled by units of spring and damping elements. The rotor blades are modeled as elastic axes with sets of lumped masses of blade segments distributed along them. The Runge-Kutta method was used to solve the equations of motion of the helicopter model. According to the Galerkin method, it was assumed that the parameters of the elastic blade motion can be treated as a combination of its bending and torsion eigen modes. For calculations, data of a hypothetical light helicopter were applied. Simulation results were presented for the cases of landing helicopter touching ground with different vertical speed and for phase of take-off including influence of rotor speed changes, wind gust and control of blade pitch. The simulation method may help to define the limits of helicopter safe operation on the landing surfaces.

Optimization Analysis of Different Excavation Offsets in Railway Pilot Tunnel by CRD Method

2014 ◽  
Vol 505-506 ◽  
pp. 134-138
Author(s):  
Chun Kui Li
Keyword(s):  
Production Efficiency ◽  
Ground Surface ◽  
Simulation Method ◽  
Subway Station ◽  
Optimization Analysis ◽  
Tunnel Excavation ◽  
Construction Model ◽  
Surface Settlements ◽  
Stress Variations ◽  
Optimal Construction

This paper focuses on the construction of 10 railway pilot tunnels by CRD method in Jiefang Road subway station in Changchun. To achieve the optimal construction offsets during the pilot tunnel excavation, reduce the impacts of group cavern effect, and maximize the production efficiency, the construction model of railway pilot tunnel in subway station was created by the finite difference software Flac3D. The author used the numerical simulation method to analyze the ground surface settlements and the stress variations with three different construction offsets. Then the optimal construction offset was obtained. It could provide a theoretical guidance to the construction of a similar project.

A Cloth Simulation Method for Cloth/ Machinery Coupled System Unified Modeling

2010 ◽  
Vol 37-38 ◽  
pp. 1-4
Author(s):  
Hai Yan Yu ◽  
Yong Xing Wang ◽  
Sheng Ze Wang ◽  
Zhao Feng Geng
Keyword(s):  
Coupled System ◽  
Simulation Method ◽  
Rigid Bodies ◽  
Simulation Software ◽  
Mechanical Modeling ◽  
Cloth Simulation ◽  
Unified Modeling ◽  
Mechanical Simulation ◽  
Cloth Modeling ◽  
Integrated Concept

In some textile machines, fabric is an inseparable element for motion and force transmitting. But the existing mechanical simulation software cannot model the fabric. This paper proposes a new cloth simulation method by blurring machinery (rigid) and cloth (soft) boundaries. This approach simulates the soft with tiny rigid bodies, large deformation with small ones. It aims to integrate the cloth modeling to the mechanical simulation system. Finally, we establish a cloth simulation model on the mechanical modeling and simulation platform, which is an embodiment of our integrated concept.

scholarly journals Characteristic parameters’ optimization based on contact pressure of sealing gasket for segmental joints

2020 ◽  
Vol 12 (7) ◽  
pp. 168781402094336
Author(s):  
Zhang Junwei ◽  
Chen Yunyao ◽  
Feng Qianke
Keyword(s):  
Numerical Simulation ◽  
Contact Pressure ◽  
Linear Regression Analysis ◽  
Control Variable ◽  
Simulation Method ◽  
Edge Length ◽  
Parameters Optimization ◽  
Shield Tunnel ◽  
Characteristic Parameters ◽  
Section Type

The aim of this study is to optimize the characteristic parameters of the segmental joints based on the contact pressure of sealing gasket. The design status of shield tunnel segment joint sealing gasket material, cross-section type, and holes arrangement through statistical data are first analyzed using the numerical simulation method. The result of this study indicates that the linear regression analysis of the outer contour parameters of the gasket was carried out using the bottom edge length of the gasket as the control variable in accordance with the statistical samples, and the influence of geometric parameters on the waterproofing design of sealing gasket is analyzed by numerical simulation from the aspects of the number of closed holes, the shape of closed holes, and the change of the opening rate in different parts. Characteristic parameters optimization of rubber hardness parameters on waterproof design of sealing gaskets have been completed on the contact pressure of sealing gasket for segmental joints. It provided some references for the design, production, processing, and quality inspection of shield tunnel gasket in the future.

scholarly journals Model of the Floating Bearing Bushing Movement in an External Gear Pump and the Relation to Its Parameterization

Energies ◽  
2021 ◽  
Vol 14 (24) ◽  
pp. 8553
Author(s):  
Miquel Torrent ◽  
Pedro Javier Gamez-Montero ◽  
Esteban Codina
Keyword(s):  
Graph Model ◽  
Field Tests ◽  
Bond Graph ◽  
Gear Pump ◽  
Characteristic Parameters ◽  
Final Model ◽  
Modeling Simulation ◽  
Starting Point ◽  
Loss Coefficients ◽  
External Gear Pump

This article presents the modeling, simulation and experimental validation of the movement of the floating bearing bushing in an external gear pump. As a starting point, a complete pump parameterization was carried out through standard tests, and these parameters were used in a first bond graph model in order to simulate the gear pump behavior. This model was experimentally validated under working conditions in field tests. Then, a sophisticated bond graph model of the movement of the floating bushing was developed from the equations that define its lubrication. Finally, as a result, both models were merged by integrating the dynamics of the floating bushing bearing with the variation of the characteristic parameters (loss coefficients). Finally, the final model was experimentally validated both in laboratory and field tests by assembling the pump in a drilling machine to drive the auxiliary movements. The novelty of this article is the conception and construction of a simple and experimentally validated tool for the study of a gear pump, which relates its macroscopic behavior as a black box (defined by the loss coefficients) to the internal changes of the unit (defined by its internal lubrication).

Development of the Analysis Model for Overhead Contact Line and Pantograph by EN Standard

2011 ◽  
Author(s):  
Jin-Hee Lee ◽  
Tae-Won Park ◽  
Sung-Pil Jung
Keyword(s):  
Contact Line ◽  
High Speed ◽  
Simulation Method ◽  
Railway Vehicle ◽  
Vehicle Speed ◽  
Analysis Model ◽  
Beam Elements ◽  
Sliding Joint ◽  
Multibody Dynamic ◽  
Catenary System

The evaluation of the contact loss of the catenary system is the highlight issue for the high-speed railway vehicle. In this paper, using the multibody dynamic analysis techniques including a flexible body, the simulation method of the catenary system is proposed. The pantograph and overhead contact line are developed by using rigid body and ANCF (Absolute Nodal Coordinate Formulation) beam elements, respectively. And relative motions are constrained by sliding joint. Using this analysis model, contact force and loss of contact are calculated according to vehicle speed. The results of the simulation are evaluated by EN 50318 that is the international standard with regard to validation of the dynamic interaction between pantograph and overhead contact line.

Airframe/intake–exhaust integration design of flying wing using a multi-bump strategy

2016 ◽  
Vol 231 (13) ◽  
pp. 2396-2407
Author(s):  
Wenbiao Gan ◽  
Zhou Zhou ◽  
Xiaocui Zhang
Keyword(s):  
Present Method ◽  
Simulation Method ◽  
Static Stability ◽  
Aerodynamic Performance ◽  
Transition Model ◽  
Optimization Framework ◽  
Flow Features ◽  
Design Effectiveness ◽  
Drag Ratio ◽  
Longitudinal Static Stability

A multi-bump strategy combines automatic optimization and flow control and is employed in airframe/intake–exhaust integration design of flying wing. The numerical simulation method of [Formula: see text] transition model is verified and used for optimization and validated analysis. According to flow features of basic integration configuration, the multi-bump strategy is proposed. Based on the strategy, the optimization framework is constructed and applied to the design. The research results show that the present method has good design effectiveness. The cruise lift-drag ratio improves 4.1% and longitudinal static stability increases 1.1% at large attack angle. The multi-bump strategy is a skillfully deflected means to improve aerodynamic performance.

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