Influence Of Ground Effect Research Articles

Analysis of The Venturi Tunnel and Ground Effect

The amendment of Formula One racing rules in 2022 has changed the situation of competitions and championships. In the 2022 season, the FIA will allow teams to use the ground effect again after 1978 to increase the possibility of overtaking and make the race more intense. The amendment is the most noticeable change in these years, and it is very effective. Wind tunnel research and the use of ground effect in the field of racing have special significance and practical value. It has always played an important role in the design and performance improvement of the car. In the design of traditional car styling, the influence of ground effect is not taken into account, so that in the course of the race, accidents often occur when the car body is off the ground. The reason is that the adhesion is reduced. The ground effect is an important method to improve the adhesion and stability of the car. In recent years, with the advancement of wind tunnel experiments, wind tunnels are gradually used in the design of racing cars. This paper will analyze the use of Venturi Wind Tunnel and ground effects in F1 and aircraft, and explain how and why adding ground effects to F1 has such a huge impact.

Sound Characteristic of Drone Fan and Influence of Ground Effect

"Flying cars", which are being developed in Japan and overseas, are expected to be a new means of transportation for people and things. But noise reduction is essential to use them in residential areas because they may not be able to meet the noise regulations. In this study, we investigated the directivity of a drone propeller’s noise using multiple microphones in order to understand the noise characteristics of a fan for vertical take-off and landing aircraft(VTOL). In addition, a target plate simulating the ground effect was installed downstream of the propeller, and changes in the sound field due to the difference in distance between the target plate and the propeller were investigated. Furthermore, we also grasped the noise reduction effect when the propeller blade has a tip anhedral.

Hurdle-Hop Simulation of Tilt-Rotor Aircraft Based on Optimal Control Theory

Aiming at simulating the hurdle-hop of tilt-rotor aircraft in forward flight near the ground, two models of numerical simulation and analysis based on optimal control theory were proposed. Firstly, Longitudinal flight dynamic model for tilt-rotor was modified considering the influence of ground effect. Secondly, the first model is combined with predicted trajectory from inverse simulation method, the inverse model of hurdle-hop of tilt-rotor is established based on optimal trajectory, and the second model is the optimal control model of unpredicted trajectory, which is formulated from the reasonable function of objective, path and boundary constraints for hurdle-hop with detailed analysis, solved two models by direct multiple shooting method and nonlinear programming algorithm. Finally, XV-15 as the sample vehicle. Two models for hurdle-hop based on optimal control theory was calculated, the history of optimal flight trajectory and control are given.

Influence of ground effect on longitudinal aerodynamic damping of wing-in-ground effect vehicles

ABSTRACTAccurate determination of longitudinal stability characteristics of wing-in-ground (WIG) effect vehicles is an essential step in their design. In order to estimate WIG vehicle’s stability, one needs to determine aerodynamic derivatives, including unsteady ones. The latter are very hard to obtain via wind tunnel tests, so traditionally they are expressed via steady derivatives. The method presented in this paper allows calculating unsteady aerodynamic derivatives by means of Reynolds-averaged Navier–Stokes simulations. The effect of different aerodynamic derivatives on stability characteristics is investigated. It is demonstrated that the decrement is two times greater in case of taking into account the unsteady aerodynamic derivatives calculated according to the presented method.

Influence of Ground Effect on Aerodynamic Performance of Maglev Train

Three-dimensioned steady compressible Reynolds-averaged equation and RNG k-e equation turbulence model were used to simulate the aerodynamic performance of the two-carriage maglev train underground effect and research the effect of different ground and track conditions on the aerodynamic performance of maglev train. Numerical results were in agreement with experiment data through the wind tunnel test and the deviation between them is below 10%. The results indicated that compared with the moving track condition, the amplitude of pressure mutation at the bottom of train near the nose is smaller, the base pressure at non-streamline part of the train had little difference and the streamline part of tail car increase slightly under stationary condition. The moving ground or track made the aerodynamic drag of head car increase and the aerodynamic drag of tail car decrease, compared with different stationary ground or track conditions, the lift of the head car decreased by 12.82% and the tail lift increased by 16.27% maximally. The change of ground and track conditions has little effect on the lift of the train and air side force of the head train, the stationary ground had a great influence on the lateral force of the tail car, which decreased by 30.41% maximally.

Detached-Eddy Simulation of Ground Effect on the Wake of a High-Speed Train

The influence of ground effect on the wake of a high-speed train (HST) is investigated by an improved delayed detached-eddy simulation. Aerodynamic forces, the time-averaged and instantaneous flow structure of the wake are explored for both the stationary ground and the moving ground. It shows that the lift force of the trailing car is overestimated, and the fluctuation of the lift and side force is much greater under the stationary ground, especially for the side force. The coexistence of multiscale vortex structures can be observed in the wake along with vortex stretching and pairing. Furthermore, the out-of-phase vortex shedding and oscillation of the longitudinal vortex pair in the wake are identified for both ground configurations. However, the dominant Strouhal number of the vortex shedding for the stationary and moving ground is 0.196 and 0.111, respectively, due to the different vorticity accumulation beneath the train. A conceptual model is proposed to interpret the mechanism of the interaction between the longitudinal vortex pair and the ground. Under the stationary ground, the vortex pair embedded in a turbulent boundary layer causes more rapid diffusion of the vorticity, leading to more intensive oscillation of the longitudinal vortex pair.

양력선 방법을 이용한 지면효과가 날개의 공력성능에 미치는 영향 분석

Weissinger의 방법을 기반으로 양력선 방법을 지면효과를 고려한 해석이 가능하도록 확장하였다. 이 방법을 이용하여 가로세로비 10의 타원형 날개와 인간동력항공기 날개에 대해 지면효과에 의한 공력성능 변화를 예측하였다. 날개가 지면에 가까워질수록 날개의 와류강도는 약간 증가하지만 내리흐름은 크게 감소한다. 인간동력항공기 날개의 경우에 날개가 지면에 가까울수록 양력은 증가하여 높이가 2m에서 양력계수는 지면효과를 받지 않을 때보다 5% 증가한다. 유도항력계수는 날개가 지면에서 스팬길이 높이에 있을 때에 지면효과가 없을 때보다 10% 감소하고 높이가 2m이면 55% 감소한다. The lifting-line method based on Weissinger's method is extended to be able to analyze the ground effect. The method is applied to predict the variation of aerodynamic performance due to ground effect for the elliptic wing with aspect ratio of 10 and the wing of human powered aircraft. While the vortex strength of the wing increases slightly, the downwash decreases significantly as the wing approaches to the ground. For the wing of human powered aircraft, the increment of lift at the height of 2m is 5% than the lift outside the influence of ground effect. The decrease of induced drag at the height of wing span is 10% and at the height of 2m is 55% than that out of ground effect.

Lifting-Line Predictions for Induced Drag and Lift in Ground Effect

Closed-form relations are presented for estimating ratios of the induced-drag and lift coefficients acting on a wing in ground effect to those acting on the same wing outside the influence of ground effect. The closed-form relations for these ground-effect influence ratios were developed by correlating results obtained from numerical solutions to Prandtl’s lifting-line theory. Results show that these influence ratios are not unique functions of the ratio of wing height to wingspan, as is sometimes suggested in the literature. These ground-effect influence ratios also depend on the wing planform, aspect ratio, and lift coefficient.

Influence of ground effect and refraction on road traffic noise

Ground effect and refraction modify geometrical spreading. In the present study a simplified model of ground effect is applied. Refraction is analyzed for the motionless atmosphere with a linear sound speed profile. Noise generated by constant speed road traffic is assessed by the time-average sound level, L AeqT -. The model of L AeqT prediction contains free parameters that are estimated from noise measurements at the site in question. The model makes possible the prediction of L AeqT at an altitude of a few tens of meters above the ground surface, within the range of a few hundred meters from the road. Contours of L AeqT = constant in the vertical plane represent the radiation pattern of road traffic noise.