Papers by Keyword: Aerodynamic Characteristics

Abstract: In order to adapt to new modern car styling, the aerodynamic numerical simulations based on computational fluid dynamics (CFD) are applied to the process of car styling. We received the early modeling design automobile aerodynamic coefficients, pressure distribution, velocity contours and other body outflow field data after the CFD post, combined with these data some advice to improve the aerodynamic drag of the designed car are given. Proposed aerodynamic automobile design method is based on numerical simulations, according to experience in air vehicle dynamics studies.

Abstract: An experimental investigation was completed with the objective of determining the performance characteristics of propeller in a Ducted-Fan Type VTOL UAV. The model consisted of three groups of two-bladed propellers with or withou an annular duct. The propellers share the same diameter but differernt blade pitchs.Model variations included the changes of the propeller and the duct shrouded combination. Static propulsion test data showed figure of lift increases with increasing blade pitch. The coaxial propellers lift did not perform as 2 times of the single propeller lift.The duct increase the duct fan system lift effectively.

Abstract: Based on the functional expression methods of wind turbine airfoils, the method of the correction to parameter factors of shape function by iterative calculation in the principle of making the residual error minimum between the fitting airfoil and the target airfoil is presented in this paper, which makes the fitting precision improved compared with the parametric representation of original airfoils. The method of the correction to parameter factors of shape function proposed in this paper is used for parametric representation of more than 20 kinds of typical airfoils and then the geometric and aerodynamic convergence are intensive studied. The results show that the minimal order of the integrated expression of airfoils is decreased by the proposed method in this paper and the mathematical models of airfoils which facilitate the unification of optimal design are established.

Abstract: In this paper, according on post rolling maneuver and the flow field, we build a CFD analysis method about momentum source model flow field and aerodynamic characteristics. Preliminary analysis of the numerical has be finished to contrast the difference of post rolling maneuver. The changing law of aerodynamic force, aerodynamic torque variation and the focus position have be given.

Abstract: The aerodynamics of the rotor/wing during conversion from rotary to fixed-wing flight was numerical investigated. It is shown that increasing forward speed can provide more thrust when rotation speed and collective angle maintain a constant, but also appear greater torque. Thrust of the rotor/wing can maintain aircraft to hover at some cases when forward speed changes with other variable. As long as major and minor rotor converse with reasonable variable change alternatively, the dual rotor/wing can converse smoothly. Moreover, the total drag of minor first conversion is smaller than that of major first conversion.

Abstract: The influence of boundary layer ingestion (BLI) on the aerodynamics of airfoil RAE2822 in subsonic is investigated by numerical method. Based on the calculation, it is found that the mass flow ratio (MFR), intake height, cowl length and intake position in the chord can affect on the lift, drag and pitching moment remarkable. Considering a maximum lift-over-drag, intake position in the chord should be rearward as possible with a certain high MFR at a small angle of attack and a considerable intake height. There is a proper MFR which makes drag lowest.

Abstract: In order to analyze the impact of engine cabin parts on aerodynamic characteristics, the related parts are divided into three categories except the engine cooling components: front thin plates (average thickness of 2mm), bottom-suspension and interior panels. The aerodynamic drag coefficient (Cd) were obtained upon the combination schemes consisting of the three types of parts by numerical simulation. Results show that Cd by simulation is closer to the test value gained by the wind tunnel experiment when front thin plates were simplified to the two-dimensional interface with zero thickness. The error is only 5.23%. Meanwhile this scheme reduces grid numbers, thus decreasing the calculating time. As the front thin plates can guide the flow, there is no difference on the Cd values gained from the model with or without bottom-suspension or interior panels when the engine cabin contains the front thin plates; while only both bottom-suspension and interior panels are removed, the Cd value can be reduced when the cabin doesn’t contain the front thin plates.

Abstract: Aerodynamic drag is one of the most important sources of the driving resistance suffered by an on-road heavy-duty truck. The previous studies have rarely involved the role of the external sun visor. Therefore, numerical method is used for the research of the influence of six kinds of sun visors differenced by shapes or layouts on the aerodynamic drag reduction. It is demonstrated that the sun visor has a great influence on the local flow field where it is fixed, while a relatively small effect on the global flow field. Moreover, compared to the original one, the C_D values of each case have different degrees of reduction which illustrates that an appropriate shape and layout of a sun visor benefits the air drag reduction, the largest decline is 4.7%.

Abstract: The principles and method of computational fluid dynamics were applied to numerical simulate the external flow field about the SUV model. The hybrid mesh of tetrahedral and triangular prismatic as well as the turbulence model of Realizable k-ε was adopted to study the flow field of SUV of flat underground. Then the SUV of complex underground was simulated with the same mesh strategy and boundary condition. The aerodynamic drag coefficient of latter was bigger than former. That illuminated the complex underground has affect to aerodynamic performance of vehicle. The wind tunnel test validated the veracity of numerical simulation. Based on that, the underground cover board was appended; the aerodynamic drag coefficient was depressed. The velocity and pressure distribution and flow line were achieved. The conclusions provide theoretical reference for the further study of aerodynamic drag reduction of complex underground.

Abstract: This article is devoted to creation of mathematical models of overhead transmission lines (OHTL), taking into account the glaze. In the studying and designing of transmission lines is often necessary to construct mathematical model taking into account the influence of natural factors and all the basic physical parameters affecting or hindering them. The main difficulties arise when describing the equation of oscillations, as they nonlinear. Numerical experiments and comparative analysis with previously reported models was presented. The main setting is the critical velocity of the wind flow and its dependence on the angle of attack to OHTL.