scholarly journals Investigation on Aircraft-store Compatibility Criteria of External Store Separation

2021 ◽  
Author(s):  
Wei Song
Keyword(s):  
Three Dimensional ◽  
Vertical Displacement ◽  
Vehicle Design ◽  
Separation System ◽  
Kinematic Parameters ◽  
Store Separation ◽  
Six Degree Of Freedom ◽  
Reynolds Average ◽  
Test Result ◽  
Dangerous Point

Abstract The evaluation of aircraft-store compatibility on external store separation is a key issue in the separation system of vehicle design. Firstly, the aircraft-store compatibility criterion of an external store separation is put forward, and then the criterion is converted to an unequal relationship between velocity and acceleration in vertical displacement and pitch angle based on the constant force assumption, which is validated by the test result of wing pylon finned store model (WPFS). The three-dimensional compressible Reynolds average N-S equation and rigid body six-degree-of-freedom motion equation (6-DOF) are solved by using unstructured dynamic overlap grid technology, to obtain the kinematic parameters of the external separation. Finally, the most dangerous point M on the tail of the external store is selected to verify the aircraft-store separation criterion. The results show that the kinematic parameters of the most dangerous point M on the tail wing of the store fall in the safe separation area, which means that the complete separated process is safe.

Time-Accurate Simulation of the Aircraft External Store Separation

2013 ◽  
Vol 444-445 ◽  
pp. 854-859
Author(s):  
Ya Chao Di ◽  
Ge Gao ◽  
Jing Lei Xu ◽  
Xing Chen Shao ◽  
Qing Yang
Keyword(s):  
Three Dimensional ◽  
Euler Method ◽  
Implicit Integration ◽  
Grid Approach ◽  
Chimera Grid ◽  
Store Separation ◽  
Unsteady Simulation ◽  
Six Degree Of Freedom ◽  
Multi Body ◽  
Flux Difference

Based on the original unsteady simulation program, the transonic aircraft external store separation was simulated by structured chimera grid approach coupled with a six degree of freedom trajectory code. The chimera grid utilized the hole-map cutting method; the searching efficiency was compared between the stencil walk and inverse map when building interpolation during the procedure. The space format utilized flux difference splitting format FDS based on Roe, moreover adding the min-mod limiter to achieve second order accuracy. The time format utilized the implicit integration and discrete scheme of the Back-Euler method. The three-dimensional trajectory of the store was captured and better fit for the experimental data. The results show that the method is correct and provides a reference for the simulation of the unsteady multi-body separation.

Parameterization of Three-Dimensional Rigid Body Guidance Incorporating Planar Gear Connections in a Spatial Closed-Loop Mechanism With Parallel Consecutive Axes

2008 ◽  
Author(s):  
Javier Rolda´n Mckinley ◽  
Carl Crane ◽  
David B. Dooner
Keyword(s):  
Computer Animation ◽  
Closed Loop ◽  
Three Dimensional ◽  
Motion Generation ◽  
Repetitive Motion ◽  
End Effector ◽  
Spatial Mechanism ◽  
Joint Axis ◽  
Position And Orientation ◽  
Six Degree Of Freedom

This paper introduces a reconfigurable closed-loop spatial mechanism that can be applied to repetitive motion tasks. The concept is to incorporate five pairs of non-circular gears into a six degree-of–freedom closed-loop spatial chain. The gear pairs are designed based on given mechanism parameters and a user defined motion specification of a coupler link of the mechanism. It is shown in the paper that planar gear pairs can be used if the spatial closed-loop chain is comprised of six pairs of parallel joint axes, i.e. the first joint axis is parallel to the second, the third is parallel to the fourth, ..., and the eleventh is parallel to the twelfth. This paper presents the synthesis of the gear pairs that satisfy a specified three-dimensional position and orientation need. Numerical approximations were used in the synthesis the non-circular gear pairs by introducing an auxiliary monotonic parameter associated to each end-effector position to parameterize the motion needs. The findings are supported by a computer animation. No previous known literature incorporates planar non-circular gears to fulfill spatial motion generation needs.

Force-based delay compensation for hardware-in-the-loop simulation divergence of 6-DOF space contact

2017 ◽  
Vol 233 (1) ◽  
pp. 151-165
Author(s):  
Qian Wang ◽  
Chenkun Qi ◽  
Feng Gao ◽  
Xianchao Zhao ◽  
Anye Ren ◽  
...  
Keyword(s):  
Dynamic Model ◽  
Dynamic Models ◽  
Contact Process ◽  
Three Dimensional ◽  
Compensation Method ◽  
Degree Of Freedom ◽  
Hardware In The Loop ◽  
Delay Compensation ◽  
Measurement Delay ◽  
Six Degree Of Freedom

The contact process of a space docking device needs verification before launching. The verification cannot only rely on the software simulation since the contact dynamic models are not accurate enough yet, especially when the geometric shape of the device is complex. Hardware-in-the-loop simulation is a choice to perform the ground test, where the contact dynamic model is replaced by a real device and the real contact occurs. However, the Hardware-in-the-loop simulation suffers from energy increase and instability since time delay is unavoidable. The existing delay compensation methods are mainly focused on a uniaxial or three-dimensional contact. In this paper, a force-based delay compensation method is proposed for the hardware-in-the-loop simulation of a six degree-of-freedom space contact. A six degree-of-freedom dynamic model of the spacecraft motion is derived, and a six degree-of-freedom delay compensation method is proposed. The delay is divided into track delay and measurement delay, which are compensated individually. Experiment results show that the proposed delay compensation method is effective for the six degree-of-freedom space contact.

Lee waves in three-dimensional stratified flow

1984 ◽  
Vol 148 ◽  
pp. 97-108 ◽  
Author(s):  
G. S. Janowitz
Keyword(s):  
Stream Function ◽  
Displacement Field ◽  
Three Dimensional ◽  
Frequency Dispersion ◽  
Vertical Displacement ◽  
Function Solution ◽  
Dispersion Surface ◽  
Phase Calculation ◽  
Lee Waves ◽  
The Green Function

The effect of a shallow isolated topography on a linearly stratified, three-dimensional, initially uniform flow in the x-direction is considered. The Green-function solution for the velocity disturbance due to this topography, which is equivalent to that due to a dipole at the origin, is shown to be without swirl, i.e. the velocity disturbance lies strictly in planes passing through the x-axis. Thus this disturbance can be described in terms of a stream function. The asymptotic forms of the wavelike portion of the stream function and the vertical displacement field are obtained. The latter is in agreement with the limited versions due to Crapper (1959). The Gaussian curvature of the zero-frequency dispersion surface is obtained analytically as a step in the stationary-phase calculation. The model is extended to determine the vertical displacement field for an arbitrary shallow topography far downstream. For topographies that are even functions of x and y it is shown that the details of the topography affect the displacement field only in the vicinity of the x-axis. Elsewhere, the amplitude of the displacement is proportional to the net volume of the topography.

Design of top mounted supersonic inlets for a cylindrical fuselage

2018 ◽  
Vol 233 (8) ◽  
pp. 2956-2979 ◽  
Author(s):  
Eiman B Saheby ◽  
Huang Gouping ◽  
Anthony Hays
Keyword(s):  
Three Dimensional ◽  
Vehicle Design ◽  
Flight Vehicle ◽  
Propulsive Efficiency ◽  
Supersonic Inlet ◽  
New Concepts ◽  
Computational Fluid Dynamics Simulations ◽  
Design Integration ◽  
Dynamics Simulations ◽  
Dimensional Wave

Designing an inlet based on the fuselage geometry and its constraints is an important part of flight vehicle design. Among the different possible configurations, design integration of a supersonic inlet with a cylindrical fuselage is a major challenge. On one hand, propulsive efficiency requirements force the designers to consider the simplest compression surfaces for the inlet entrance geometries and on the other hand, the considerable drag of inlet/diverter integrations needs to be minimized, which can affect the inlet. In this paper, two new concepts as a replacement for a top mounted pitot inlet are presented: a three-dimensional wave-derived inlet and a trigonometric bump inlet. They are designed based on computational fluid dynamics simulations and their performance has been measured and compared with the initial single normal shock inlet as a baseline.

Determination of the Workspace of 6-DOF Parallel Manipulators

1989 ◽  
Author(s):  
C. Gosselin
Keyword(s):  
Parallel Manipulator ◽  
Graphical Representation ◽  
Three Dimensional ◽  
Parallel Manipulators ◽  
Degree Of Freedom ◽  
Geometrical Properties ◽  
Cartesian Space ◽  
Six Degree Of Freedom

Abstract This paper presents an algorithm for the determination of the workspace of parallel manipulators. The method described here, which is based on geometrical properties of the workspace, leads to a simple graphical representation of the regions of the three-dimensional Cartesian space that are attainable by the manipulator with a given orientation of the platform. Moreover, the volume of the workspace can be easily computed by performing an integration on its boundary, which is obtained from the algorithm. Examples are included to illustrate the application of the method to a six-degree-of-freedom fully-parallel manipulator.

Modeling the Flow over Planing Hulls with Ventilated or Cavitating Steps

2015 ◽  
Author(s):  
Christopher O'Reilly ◽  
Matthew Murphy ◽  
Dominic Piro ◽  
Neal Fine
Keyword(s):  
Numerical Model ◽  
Three Dimensional ◽  
Degree Of Freedom ◽  
Linear Solution ◽  
3 Dimensional ◽  
Six Degree Of Freedom

A numerical model is being developed to solve for six-degree-of-freedom forces experienced by a cavitating, stepped planing hull. An approach to solving the cavitation or ventilation problem is described. Next a method for solving for spray roots on the hull is detailed and a method for approximating the transom wake for a 3 dimensional planing hull is discussed. Results of the cavity solver for a three-dimensional linear solution are presented. Finally results in the context of three-dimensional planing hull steady resistance simulations are presented and compared to RANS CFD and tow tank experiments.

Three Dimensional Robot Path Planning With Workspace Considerations

1992 ◽  
Author(s):  
C. Y. Liu ◽  
R. W. Mayne
Keyword(s):  
Path Planning ◽  
Three Dimensional ◽  
Optimization Methods ◽  
Planning Problem ◽  
Robot Path Planning ◽  
Recursive Quadratic Programming ◽  
Six Degree Of Freedom ◽  
Nonlinear Programming Method ◽  
Path Planning Problem ◽  
Robot Path

Abstract This paper considers the problem of robot path planning by optimization methods. It focuses on the use of recursive quadratic programming (RQP) for the optimization process and presents a formulation of the three dimensional path planning problem developed for compatibility with the RQP selling. An approach 10 distance-to-contact and interference calculations appropriate for RQP is described as well as a strategy for gradient computations which are critical to applying any efficient nonlinear programming method. Symbolic computation has been used for general six degree-of-freedom transformations of the robot links and to provide analytical derivative expressions. Example problems in path planning are presented for a simple 3-D robot. One example includes adjustments in geometry and introduces the concept of integrating 3-D path planning with geometric design.

Vehicle Body and Roll Cage Assessment involving Frontal, Side and Roll-over Crash Analysis by FEA using LS-Dyna

2021 ◽  
Vol 13 (4) ◽  
Author(s):  
V. Hariram ◽  
K. Venkatesh ◽  
M. Venkata Saidev ◽  
M. Surisetty Mahesh ◽  
M. Vinothkumar ◽  
...  
Keyword(s):  
Carbon Fiber ◽  
Structural Steel ◽  
Three Dimensional ◽  
The Body ◽  
Vehicle Body ◽  
Crash Analysis ◽  
Steel Members ◽  
Vehicle Collision ◽  
Six Degree Of Freedom ◽  
Frontal Side

Simulating the vehicle collision has gained importance in the automotive sector due to its accuracy, cost effectiveness and enhanced reliability. It aids in improving the safety of driver and passenger and also examine the cause of crash or collision. This numerical analysis investigates the materials capability to enhance safety. A three-dimensional vehicle model was developed along with its roll cage using solid work tool. Hypermesh work bench was employed to discretise the sensitive parts of the body and roll cage using beam 189 element having six degree of freedom at each node. The existing structural steel members were replaced with reinforced carbon fibre in all the sensitive part of the body and roll cage and its structural stability was assessed using the frontal, side and roll over crash simulation using LS Dyna. This investigation also reveals the change in internal energy, kinetic energy absorption and momentum transfer for both structural steel and carbon fiber under all the crash scenarios. The outcomes of this numerical investigation proved that the reinforced carbon fiber can be effectively replaced with the structural steel to enhance safety.

Sign in / Sign up

Export Citation Format

Share Document