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Investigations into ground effect phenomena about aerofoils are typically conducted on either an upright (lift‐producing) or inverted (downforce‐producing) configuration, in isolation. This limited approach does not promote a holistic understanding of how ground effect influences aerofoils. This paper aims to address this issue.

A two‐dimensional computational fluid dynamics investigation was conducted on the highly cambered Tyrrell aerofoil, in both its upright and inverted configurations, in order to better understand ground effect phenomena by observing how it influences each configuration differently. The trends in force and flow field behaviour were observed at various ground clearances through observation of the normal and drag forces and pressure coefficient plots. The aerofoil was held stationary and at a constant angle of attack of 6 degrees, with a moving ground plane to simulate the correct relative motion.

The different ground effect mechanisms that occur on each configuration are highlighted and explained. It is shown how ground effect manifests through these different phenomena and that there are general or overarching mechanisms that influence both configurations. These general mechanisms allow unintuitive phenomena, such as the downward movement of the stagnation point on both configurations, to be explained.

Overarching mechanisms of ground effect are discovered which are of value in any situation in which ground effect aerodynamics is to be exploited.

The purpose of this paper is to study the aerodynamic characteristics of Ahmed body in longitudinal and lateral platoons under crosswind by computational fluid dynamics simulation. It helps to improve the aerodynamic characteristics of vehicles by providing theoretical basis and engineering direction for the development and progress of intelligent transportation.

A two-car platoon model is used to compare with the experiment to prove the accuracy of the simulation method. The simplified Ahmed body model and the Reynolds Averaged N-S equation method are used to study the aerodynamic characteristics of vehicles at different distances under cross-winds.

When the longitudinal distance x/L = 0.25, the drag coefficients of the middle and trailing cars at β = 30° are improved by about 272% and 160% compared with β = 10°. The side force coefficients of the middle and trailing cars are increased by 50% and 62%. When the lateral distance y/W = 0.25, the side force coefficients of left and middle cars at β = 30° are reduced by 38% and 37.5% compared with β = 10°. However, the side force coefficient of the right car are increased by about 84.3%.

Most of the researches focus on the overtaking process, and there are few researches on the neat lateral platoon. The innovation of this paper is that in addition to studying the aerodynamic characteristics of longitudinal driving, the aerodynamic characteristics of neat lateral driving are also studied, and crosswind conditions are added. The authors hope to contribute to the development of intelligent transportation.

For flow around elongated bluff bodies, flow separations would occur over both leading and trailing edges. Interactions between these two separations can be established through acoustic perturbation. In this paper, the flow and the acoustic fields of a D-shaped bluff body (length-to-height ratio L/H = 3.64) are investigated at height-based Reynolds number Re = 23,000 by experimental and numerical methods. The purpose of this paper is to study the acoustic feedback in the interaction of these two separated flows.

The flow field is measured by particle image velocimetry, hotwire velocimetry and surface oil flow visualization. The acoustic field is modeled in two dimensions by direct aeroacoustic simulation, which solves the compressible Navier–Stokes equations. The simulation is validated against the experimental results.

Separations occur at both the leading and the trailing edges. The leading-edge separation point and the reattaching flow oscillate in accordance with the trailing-edge vortex shedding. Significant pressure waves are generated at the trailing edge by the vortex shedding rather than the leading-edge vortices. Pressure-based cross-correlation analysis is conducted to clarify the effect of the pressure waves on the leading-edge flow structures.

The understanding of interactions of separated flows over elongated bluff bodies helps to predict aerodynamic drag, structural vibration and noise in engineering applications, such as the aerodynamics of buildings, bridges and road vehicles.

This paper clarifies the influence of acoustic perturbations in the interaction of separated flows over a D-shaped bluff body. The contribution of the leading- and the trailing-edge vortex in generating acoustic perturbations is investigated as well.

The main purpose of this paper is to gain a better understanding of the transient aerodynamic characteristics of moving windshield wipers. In addition, this paper also strives to illustrate and clarify how the wiper motion impacts the airflow structure; the aerodynamic interaction of two wipers is also discussed.

A standard vehicle model proposed by the Motor Industry Research Association and a pair of simplified bone wipers are introduced, and a dynamic mesh technique and user-defined functions are used to achieve the wiper motion. Finite volume methods and large eddy simulation (LES) are used to simulate the transient airflow field. The simulation results are validated through the wind tunnel test.

The results obtained from the study are presented graphically, and pressure, velocity distributions, airflow structures, aerodynamic drag and lift force are shown. Significant influences of wiper motion on airflow structures are achieved. The maximum value of aerodynamic lift and drag force exists when wipers are rotating and there is a certain change rule. The aerodynamic lift and drag force when wipers are rotating downward is greater than when wipers are rotating upward, and the force when rotating upward is greater than that when steady. The aerodynamic lift and drag forces of the driver-side wiper is greater than those of the passenger-side wiper.

The LES method in combination with dynamic mesh technique to study the transient aerodynamic characteristics of windshield wipers is relatively new.

This paper aims to propose a precise turbulence model for automobile aerodynamics simulation, which can predict flow separation and reattachment phenomena more accurately.

As the results of wake flow simulation with commonly used turbulence models are unsatisfactory, by introducing a nonlinear Reynolds stress term and combining the detached Eddy simulation (DES) model, this paper proposes a nonlinear-low-Reynolds number (LRN)/DES turbulence model. The turbulence model is verified in a backward-facing step case and applied in the flow field analysis of the Ahmed model. Several widely applied turbulence models are compared with the nonlinear-LRN/DES model and the experimental data of the above cases.

Compared with the experimental data and several turbulence models, the nonlinear-LRN/DES model gives better agreement with the experiment and can predict the automobile wake flow structures and aerodynamic characteristics more accurately.

The nonlinear-LRN/DES model proposed in this paper suffers from separation delays when simulating the separation flows above the rear slant of the Ahmed body. Therefore, more factors need to be considered to further improve the accuracy of the model.

This paper proposes a turbulence model that can more accurately simulate the wake flow field structure of automobiles, which is valuable for improving the calculation accuracy of the aerodynamic characteristics of automobiles.

Based on the nonlinear eddy viscosity method and the scale resolved simulation, a nonlinear-LRN/DES turbulence model including the nonlinear Reynolds stress terms for separation and reattachment prediction, as well as the wake vortex structure prediction is first proposed.

The flow topology for multi-disciplinary configuration (MULDICON) wing is very complicated and nonlinear at low to high angle of attack (AOA). This paper aims to provide the correlation between the unsteadiness and uncertainties of the flow topology and aerodynamic forces and moments above MULDICON WING at a medium to a higher AOA.

The experimental and computational fluid dynamics methods were used to investigate a generic MULDICON wing. During the experiment, the AOA were varied from α = 5° to 30°, whereas yaw angle varies between β = ±20° and Reynolds number between Re = 3.0 × 10⁵ and Re = 4.50 × 10⁵. During the experiments steady-state loading, dynamic loading and flow visualization wind tunnel methods were used.

The standard deviation quantified the unsteadiness and uncertainties of flow topology and predicted that they significantly affect the pitching moment (C_m) at medium to higher AOA. A strong correlation between flow topology and C_m was exhibited, and the experiment data was well validated by previous numerical work. The aerodynamic center was not fixed and shifted toward the wing apex when AOA is increasing. For a = 10°, the flow becomes more asymmetric. Power spectral densities plots quantify the flow separation (apex vortex, leading-edge vortex and vortex breakdown) over the MULDICON wing.

The application and comparison of steady-state and dynamic loading data to quantify the unsteadiness and uncertainties of flow topology above the MULDICON wing.

Summarises the report of a Sensors Task Force which was formed as part of the UK Technology Foresight exercise. Examines the various markets for sensor technology, both globally and in the UK. Details the opportunities and challenges, market pull factors, and the most promising technologies and application areas.

A recursive scheme for the ALIENOR method is proposed as a remedy for the difficulties induced by the method. A progressive focusing on the most promising region, in combination with a variation of the density of the alpha-dense curve, is proposed.

ALIENOR method is aimed at reducing the space dimensions of an optimization problem by spanning it by using a single alpha-dense curve: the curvilinear abscissa along the curve becomes the only design parameter for any design space. As a counterpart, the transformation of the objective function in the projected space is much more difficult to tackle.

A fine tuning of the procedure has been performed in order to identity the correct balance between the different elements of the procedure. The proposed approach has been tested by using a set of algebraic functions with up to 1,024 design variables, demonstrating the ability of the method in solving large scale optimization problem. Also an industrial application is presented.

In the knowledge of the author there is not a similar paper in the current literature.

The purpose of this paper is to investigate the aerodynamics of wing in ground effect with tiltable endplates for a new type wing‐in‐ground effect (WIG) craft.

The concept of tiltable endplates was implemented into the design of a WIG craft. Numerical investigation on aerodynamics of the tiltable endplate was carried out. The endplate effect on aerodynamics was deeply investigated with a rectangular wing at given angle of attack and flight height. The size of endplate relative to whole wing was then studied based on given endplate deflection angle and flight height. Finally, aerodynamics and flow of tiltable endplate in various flight heights and endplate deflection angles were analyzed. Aerodynamics, pressure and wingtip vortex were recorded in the study.

Endplate influences development of wingtip vortex and improves aerodynamics. Tiltable endplate can enable WIG craft to yield improved aerodynamic performance and worthwhile economy improvements on long‐distance flights in and out of ground effect (OGE).

The results are entirely based on computational fluid dynamics (CFD). The gap between “numerical world” and “real world” depends on development and appropriate application of CFD. The current work shows further understanding of ground effect and aerodynamics of wing in ground effect.

The aerodynamics and aerodynamic optimization of wing in ground effect are of the great importance for WIG craft. The work improves the design and research on aerodynamics of WIG craft.

The concept of tiltable endplate for a new type wing in ground effect allows WIG craft to achieve good aerodynamic performance not only in ground effect but also in OGE. This was studied and proved in the current work.

Hydroelectric power is widely used because it is environmental friendly, renewable and green. The cavitation is an inevitable phenomenon during the operation of hydro turbine, which is related to the efficiency and service life of the unit. This paper aims to discriminate the phenomenon of the incipient cavitation, prevent the early destruction and avoid the irreversible damage to hydro turbine.

The paper tries to find out the characteristics of cavitation entirely through a variety of features. The method comprises collection of the signals using a hydrophone, acceleration sensor and acoustic emission sensor; analyzing cavitation signal by using the way of wavelet time-frequency, peak factor and power spectral density; and comparing the different wavelet basis for analyzing signals and find the most suitable one.

The analyzed results show that the wavelet basis of morlet is more suitable for the cavitation signals. The hydrophone can distinguish the different operating conditions and discriminate the difference between the phenomenon of incipient cavitation and the other state of cavitation. The results show that when the hydrophone and acceleration sensors are used, the accuracy rate goes up to 75 per cent, which meets the requirements for the detection for incipient cavitation.

This paper focuses on finding the best sensor to discriminate the operating state of incipient cavitation to prevent early destruction.