Ground manoeuvres of aircrafts in narrow spaces by all-wheel-steering

2021 ◽  
pp. 095440622110095
Author(s):  
Francesco Sorge
Keyword(s):  
Aerodynamic Forces ◽  
Low Speed ◽  
Critical Speeds ◽  
Flight Decks ◽  
All Wheel Steering ◽  
Point Trajectories

The present analysis deals with the ground taxiing of aircrafts and considers, in particular, their turning at rather low speed with very small path radii among obstacles that may be very close to each other, for example inside the hangars or on the flight decks of the aircraft carriers where other planes stand stationary. To succeed in this operation, it is crucial to optimize the path and avoid dangerous collisions or, more generally, the interference in the ground projection between the obstacles and the band enclosing all the point trajectories of the plane. The essential innovation here proposed for this purpose consists in making all the wheels of the undercarriage steerable, assuming electrically motorized struts, and in searching for the best correlation among the steering angles in order to optimize the path. The geometrical and dynamical nonlinearities due to the relatively large steering angles, to the changes of the cornering stiffness with the vertical loads on the wheels and to the inertial and the aerodynamic forces will be included in the analysis. The rollover critical speeds will be calculated on varying the path radius.

scholarly journals Numerical Simulation for Engine/Airframe Interaction Effects of the BWB300 on Aerodynamic Performances

2019 ◽  
Vol 2019 ◽  
pp. 1-15 ◽  
Author(s):  
Gang Yu ◽  
Dong Li ◽  
Yue Shu ◽  
Zeyu Zhang
Keyword(s):  
Numerical Simulation ◽  
High Speed ◽  
Separated Flow ◽  
Simulation Method ◽  
Interaction Effects ◽  
Surface Flow ◽  
Concept Design ◽  
Aerodynamic Forces ◽  
Low Speed ◽  
Aerodynamic Performances

The engine/airframe interaction effects of the BWB300 on aerodynamic performances were analyzed by using the numerical simulation method. The BWB300 is a 300-seat Blended Wing Body airplane designed by the Airplane Concept Design Institute of Northwestern Polytechnical University. The engine model used for simulation was simplified as a powered nacelle. The results indicated the following: at high speed, although the engine/airframe interaction effects on the aerodynamic forces were not significant, the airframe’s upper surface flow was greatly changed; at low speed, the airframe’s aerodynamic forces (of the airplane with/without the engine) were greatly different, especially at high attack angles, i.e., the effect of the engine suction caused the engine configuration aerodynamic forces of the airframe to be bigger than those without the engine; and the engine’s installation resulting in the different development of flow separation at the airframe’s upper surface caused greater obvious differences between the 2 configurations at high angles and low speed. Moreover, at low-speed high attack angles, the separated flow from the blended area caused serious distortion at the fan inlet of the engine.

Steering Analysis of Multi-Axle Vehicle Based on ADAMS/VIEW

2012 ◽  
Vol 538-541 ◽  
pp. 2878-2881
Author(s):  
Yong Qiang Zhu ◽  
Ping Xia Zhang
Keyword(s):  
High Speed ◽  
Large Angle ◽  
Lateral Acceleration ◽  
Steering Wheel ◽  
Low Speed ◽  
Vehicle Simulation ◽  
Yaw Rate ◽  
Wheel Turning ◽  
Double Phase ◽  
All Wheel Steering

In order to improve low-speed flexibility and high-speed handling and stability of multi-axle vehicle, a double-phase steering system was designed with planetary gear system. An in-phase steering mode is used when steering wheel turning in small angle. A adverse-phase steering mode is used when steering wheel turning in large angle. A five-axle vehicle simulation model was established with software ADAMS/VIEW. The research of all-wheel steering and non-all-wheel steering for high speed and low speed was respectively processed. When running in high speed, the lateral acceleration and yaw rate of the centroid are significantly lower when rear wheels steering in in-phase mode than the rear wheels not turning, which makes the possibility of roll and drift decrease, when vehicle overtaking in high-speed. When running in low speed, compared with rear wheels not steering, when rear wheels sreering, lateral acceleration increased by only 12.8%, yaw rate is 17.3% higher, diameter of the centroid trajectory is reduced by 12.9%, which greatly increases the mobility and flexibility of the multi-axle vehicle when turning at low speed.

Modeling of Decelerated Descent of an Elongated Body With Vectored Thrust

2018 ◽  
Author(s):  
Konstantin I. Matveev ◽  
John P. Swensen ◽  
Matthew E. Taylor
Keyword(s):  
Target Location ◽  
Thrust Force ◽  
Cylindrical Body ◽  
The Body ◽  
Dynamics Model ◽  
Aerodynamic Forces ◽  
Low Speed ◽  
Stable Orientation ◽  
The Subject ◽  
Vectored Thrust

The subject of this study is a simplified model of an elongated body intended for controlled, low-speed landing after being released far above the ground. The envisioned system is structurally simple and compact. It comprises a cylindrical body with a vectored propulsor attached to its upper end. Far from the ground a low-magnitude thrust force directs the body toward the target site and maintains stable orientation, whereas near the ground higher thrust decelerates and directs the body to ensure low-speed landing near the target location. A 6-DOF dynamics model is applied for simulating the body descent. A strip approach is used for evaluating aerodynamic forces on the body. The thrust magnitude and direction are the controlled parameters. Results of simulations are presented for several scenarios of the body descending on the ground in calm air and in the presence of wind.

scholarly journals A Study of Multi-Objective Aerodynamic Optimization Design for Variable Camber Airfoils and High Lift Devices

2018 ◽  
Vol 36 (1) ◽  
pp. 83-90
Author(s):  
Wangyi Zhou ◽  
Junqiang Bai ◽  
Lei Qiao ◽  
Yasong Qiu ◽  
Rui Liu ◽  
...  
Keyword(s):  
High Speed ◽  
Optimization Design ◽  
Deflection Angle ◽  
Aerodynamic Optimization ◽  
Aerodynamic Forces ◽  
High Lift ◽  
Low Speed ◽  
Multi Objective ◽  
Multi Objective Genetic Algorithm ◽  
Design Variables

Aiming at the synthetical optimization of the aerodynamic performance between the low-speed condition of two-dimensional high lift devices during take-off and landing phase and the high-speed condition of variable camber airfoil during cruise phase, an aerodynamic optimization design method for high lift device based on Kriging based surrogate model and multi-objective genetic algorithm has been developed. With the application of Adaptive Dropped Hinge Flap mechanism, the low-speed take-off and landing performance and high-speed cruise performance of the aircraft is improved by coupling deflection of the flap and spoiler. The position of flap hinge, deflection angle of spoiler and deflection angle of flap are taken as design variables; The Navier-Stokes equations are used to predict the aerodynamic forces of initial samples; The Kriging based surrogate model is employed to establish the algebraic relation between design variables and aerodynamic forces at take off, landing and cruise, obtaining four efficient prediction models for aerodynamic forces; Multi-objective optimization design with multi-objective genetic algorithm is conducted on the basis of surrogate models. The automatic generation of computational grid is achieved by the mesh deformation method based on RBF (Radial Basis Function) when the design variables change. On the basis of efficient global multi-objective optimization design platform, the synthetical optimization of high-speed and low-speed aerodynamic performance is conducted; The multi-objective solution set of the Pareto frontier is verified and analyzed, and the optimal solution with well matched high and low speed performance is selected.

All Wheel Steering System

2015 ◽  
Vol 7 (02) ◽  
pp. 105-108
Author(s):  
Sanjay Kumar Singh ◽  
Sanjay Kumar Sharma ◽  
Akhilesh Kumar Verma
Keyword(s):  
Steering System ◽  
Vehicle Stability ◽  
Handling System ◽  
Low Speed ◽  
Steering Mechanism ◽  
All Wheel Steering ◽  
Response Increase ◽  
Vehicle Response ◽  
Turning Radius ◽  
System Mechanism

Now a days most of the vehicles are use the two wheel steering system mechanism as their main handling system but, the efficiency of two wheel steering vehicle is proven to be low compared to all wheel steering vehicles. All wheel steering system can be employed in some vehicles to improve vehicle response, increase vehicle stability while moving at certain speed, or to decrease turning radius at low speed. All wheel steering is a technologically, tremendous effort on heavy loaded vehicles. Hence, there is a requirement of a mechanism which result in less turning radius and it can be achieved by implementing all wheel steering mechanism instead of regular two wheel steering.

scholarly journals Experimental Investigation and Theoretical Prediction of Flutter Behaviour of a Plane Cascade in Low-Speed Flow

1996 ◽  
Author(s):  
H. Hennings ◽  
W. Send
Keyword(s):  
Cross Section ◽  
Transonic Flow ◽  
Close Relation ◽  
Test Facility ◽  
Aerodynamic Forces ◽  
Low Speed ◽  
Air Stream ◽  
Speed Flow ◽  
Sensitive Dependence ◽  
Flutter Boundary

The Institute of Aeroelasticity operates a test facility which enables aeroelastic investigations of plane cascades in low-speed flow. The test stand serves as a pilot facility to develop tools for analogous investigations in transonic flow. Eleven blades are elastically suspended in a windtunnel with a 1 × 0.2 m2 cross section. This paper describes the experimental method of determining the flutter boundary by extrapolation of the results measured in subcritical flow. A 2D theoretical model of the 11 blades including the windtunnel walls permits the computation of unsteady pressures, forces and moments in close relation to the experiment. The prediction of flutter is compared with experimental results. In the present investigation, the motion of the blades is constrained to pitch around mid-chord. The vibrating blades are mechanically uncoupled. Any interaction between the blades is effected by the air stream, leading to a sensitive dependence on the aerodynamic forces.

Experimental Investigation and Theoretical Predication of Flutter Behavior of a Plane Cascade in Low Speed Flow

1998 ◽  
Vol 120 (4) ◽  
pp. 766-774 ◽  
Author(s):  
H. Hennings ◽  
W. Send
Keyword(s):  
Cross Section ◽  
Transonic Flow ◽  
Close Relation ◽  
Test Facility ◽  
Aerodynamic Forces ◽  
Low Speed ◽  
Air Stream ◽  
Speed Flow ◽  
Sensitive Dependence ◽  
Flutter Boundary

The Institute of Aeroelasticity operates a test facility which enables aeroelastic investigations of plane cascades in low-speed flow. The test stand serves as a pilot facility to develop tools for analogous investigations in transonic flow. Eleven blades are elastically suspended in a windtunnel with a 1 × 0.2 m2 cross section. This paper describes the experimental method of determining the flutter boundary by extrapolation of the results measured in subcritical flow. A two-dimensional theoretical model of the 11 blades, including the windtunnel walls, permits the computation of unsteady pressures, forces, and moments in close relation to the experiment. The prediction of flutter is compared with experimental results. In the present investigation, the motion of the blades is constrained to pitch around mid-chord. The vibrating blades are mechanically uncoupled. Any interaction between the blades is effected by the air stream, leading to a sensitive dependence on the aerodynamic forces.

New ultrastructural findings about Borrelia burgdorferi by cryofixation, negative staining, thin sectioning and scanning techniques

1990 ◽  
Vol 48 (3) ◽  
pp. 582-583
Author(s):  
S. F. Hayes ◽  
M. D. Corwin ◽  
T. G. Schwan ◽  
D. W. Dorward ◽  
W. Burgdorfer
Keyword(s):  
Lyme Disease ◽  
Borrelia Burgdorferi ◽  
Structural Characterization ◽  
Negative Staining ◽  
Low Speed ◽  
Thin Sectioning ◽  
Ultrastructural Findings

Characterization of Borrelia burgdorferi strains by means of negative staining EM has become an integral part of many studies related to the biology of the Lyme disease organism. However, relying solely upon negative staining to compare new isolates with prototype B31 or other borreliae is often unsatisfactory. To obtain more satisfactory results, we have relied upon a correlative approach encompassing a variety EM techniques, i.e., scanning for topographical features and cryotomy, negative staining and thin sectioning to provide a more complete structural characterization of B. burgdorferi.For characterization, isolates of B. burgdorferi were cultured in BSK II media from which they were removed by low speed centrifugation. The sedimented borrelia were carefully resuspended in stabilizing buffer so as to preserve their features for scanning and negative staining. Alternatively, others were prepared for conventional thin sectioning and for cryotomy using modified procedures. For thin sectioning, the fixative described by Ito, et al.

Reopening of Chronic Coronary Occlusions by Low-Speed Rotational Angioplasty

1994 ◽  
Vol 12 (4) ◽  
pp. 623-629 ◽  
Author(s):  
Andreas Hartmann ◽  
Martin Kaltenbach
Keyword(s):  
Low Speed
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