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In this paper, a completely numerical simulation model of a tilt rotor helicopter is established. Based on the hierarchical and modular modeling principles, the whole simulation model is finally realized on the Simulink platform. Then a sliding mode variable structure controller based on expansion state observer (ESO) is designed in order to realize the attitude control of this nonlinear and strong...
This paper presents a computational framework to identify the effects of wind on the dynamics of a quadrotor unmanned aerial vehicle. Then, using the identified model, the strength and the direction of the wind are estimated with the inertial measurements. The proposed approach is based on a geometric numerical integrator on the special Euclidean group, referred to as a Lie group variational integrator...
In this paper, the dynamics of a flapping wing vehicle are studied. A quasi-steady model is developed to analyze its aerodynamic forces and moments. The unsteady effects are considered both in hovering state and forward flight state. Different from existing flapping wing vehicle dynamics model, the rudder's dynamics are concurrently considered in the proposed one. Numerical simulation is conducted...
Numerical simulation results on the effect of corner arc (radius ‘r’) on the aerodynamic characteristics of a square section cylinder (side dimension, B) are presented in this paper. Simulation was carried out by using the commercial code ANSYS-Fluent at a Reynolds value of 2100 (based on B). Results show that as r/B ratio (CR) increases, coefficients of drag and lift decrease till CR = 0.2 further...
Effects of turbulent flow to dynamic characteristic of high sweep-back angle Delta wing were performed by numerical (SIM) and experiment (EXP) method in subsonic flow. The numerical method was based on CFD methods using ANSYS/FLUENT software, while experiment method was conducted in low speed wind tunnel (Mach number M=0.1). At low Reynolds number, air velocity 2.5m/s, the Delta wing was investigated...
To investigate aeroelastic effects of model flexible wings on aerodynamic performance in forward flapping flight, a monolithic approach and a MATLAB program were established and built based on the Peter's unsteady flow theory and finite element analyses. The kinematic parameters, including flapping stroke angle, flapping frequency and forward velocity were studied to investigate the effect on aerodynamics...
Numerical investigations on stratospheric airships of different tail configurations are conducted based on the Reynolds-averaged N-S equations and k-ω SST turbulent model in the condition of the same volume and total area of the tails. The influence of tail configurations on the force and moment characteristics as well as flow phenomena on both hull and fins are analyzed. In particular, the hull-fin...
In this work is treated the design of two controllers applied to a fixed-wing unmanned aerial vehicle (UAV). The aim is to stabilize an UAV type Cessna 182 in longitudinal and in lateral-directional flight. The UAV is identified by decoupling the system to longitudinal and lateral-directional modes and using off line modeling. The resulting models represent approximately the UAV because of nonlinearities...
The drag coefficient and Magnus coefficient are different along with the geometric parameters of target object when calculating and simulating the trajectory. Generally, the coefficients are measured in wind-tunnel via repeated experiments, and only for object which have the same shape and geometric parameters. This paper proposes a numerical iterative algorithm based on hierarchical optimization...
The performance and structure of the internal flow field of counterflow thrust vectoring nozzle under the impact of the external flow were studied by numerical simulation, considering the angle of external flow on the vectoring angle and the mass flux ratio of secondary flow. The results show that, when the external flow is of the same Mach number and the angle of the external flow increase in positive...
A set of quasi CAV model composed of a carrier model and a internal store model was designed consulting opening documents, and it was used to study the multi-body interference during separating by grid force measurement at supersonic in 0.6m×0.6m transonic wind tunnel. The results show that the aerodynamic characteristics of the loading model would change dramatically during the separation. Two factors...
This paper presents dynamic modeling for cross-spring pivots, based on the Beam Constraint Model (BCM) and Lagrangian method. The effect of vertical force is included in this model. The first natural frequency of the cross-spring pivot under vertical force is derived. The effects on the first natural frequency imposed by manufacturing errors are studied. The model predictions of the first natural...
Wind tunnel testing is the effective method to research high speed train aerodynamics. It is one of the key steps to ascertain the model scale for wind tunnel testing, because scaled model is always introduced into wind tunnel testing, due to the huge body. Based on the structure of aerodynamic and aero-acoustic wind tunnel, using computational fluid dynamics (CFD), focus on middle car of three connected...
To study the effect of the vehicle's figure simplification on the vehicle's lift force, an 1∶1 scaled vehicle model was applied as the study object. Simulations for the vehicle with four different simplified figures were carried using CFD method. By comparing and analyzing the obtained results, the reasons for the differences among the four kinds of figures were found out. And the error ranges for...
Based on the classic scheme of proportional , integral and derivative (PID) control, we present the design of a nonlinear controller, which aims to regulate the posture (position and orientation) of a 6 d.o.f. (degrees of freedom) aerial vehicle called Quadrotor. In particular, the Quadrotor horizontal position is controlled by PI actions, while the Quadrotor orientation and vertical position are...
The pintle controlled thrust regulating mechanism is an effective means to realize thrust real-time regulation of solid-rocket engine. Factors of thrust regulating range and speed, thrust loss, reacting force on pintle section should be considered in pintle design. Numerical simulation on inner flow field of nozzle for different radius pintle, different head coning of pointed cone pintle and different...
We investigate the flight characteristics of the beetle (Allomyrina dichotoma), which has hind wings and elytra, based on the numerical simulation. Flapping kinematics of both the hind wings and the elytra are obtained by visualization in a wind tunnel. One can observe veins and membrane on the hind wings, which allow corrugated patterns on the cross section of the wing along streamwise direction...
This paper proposes a practical method to identify the parameters in the train motion model. Focusing on the repeatability of the train motion system, the new method develops an iterative learning identifier to estimate the parameters through repetitive trials. With rigorous analysis, it is shown that each parameter can effectively converge to its actual point after enough iteration. At last, the...
The main objective of this paper is to numerically investigate the effects of a divert jet on the overall aerodynamic performance of a generic interceptor missile operating at moderate angle attack. A generic missile interceptor configuration consisting of a long, slender body containing tail fins is simulated in this study. Firstly, K-epsiv, K-omega and S-A turbulent model are evaluated in simulating...
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