Transonic and supersonic ground effect aerodynamics

Doig, Graham

doi:10.1016/j.paerosci.2014.02.002

Cited by 29 publications

(23 citation statements)

References 78 publications

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“…For this reason, additional simulations were run as transient (unsteady RANS) and the flowfields were time-averaged in order to assess the suitability of steady-state simulations for the present investigation. Because of a similar industry standard, all simulations were run as incompressible, although local density changes, particularly in the contact patch region, may have a slight influence on the flow (Doig et al, 2011;Doig, 2014;Keogh et al 2014).…”

Section: Methodsmentioning

confidence: 99%

The effects of simplifications on isolated wheel aerodynamics

Diasinos

Barber

Doig

2015

Journal of Wind Engineering and Industrial Aerodynamics

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a b s t r a c tIn order to study the aerodynamic forces and flow features of rotating wheels, compromises and simplifications are often made in wind tunnel testing, and more frequently so in numerical modelling. A CFD approach similar to that commonly used in industry was utilised to investigate common assumptions involving; the influence of geometric fidelity in wheel hub regions, ground representation, the modelling of the contact patch, and the effects of rotation on separation. It was found that the separation and wake characteristics were strongly influenced by the rotation of the wheel; the separation point changed by as much as 90% compared to a stationary wheel, and drag was close to 20% less -downforce was approximately 40% greater. In addition, the modelling of the contact patch, treated here as a small step to facilitate skew-free meshing necessary for a reliable converged result, was seen to cause up to a 52% difference in predicted lift characteristics, and an increase in the step of just 2 mm decreased the maximum wake thickness by close to 50% -considerable changes stemming from superficially-minor simplifications. Including indented wheel hubs proved to be more influential on the production of vortices and wake structures, causing the merging of previously-separate vortex structures. The results point to a need for very careful evaluation of the goals of any study when determining which simplifications can be made in both physical testing and numerical analysis.

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Section: Methodsmentioning

confidence: 99%

The effects of simplifications on isolated wheel aerodynamics

Diasinos

Barber

Doig

2015

Journal of Wind Engineering and Industrial Aerodynamics

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“…The turbulence model used for all GCI calculations was the Spalart-Allmaras (SA) model, a one-equation turbulence model developed specifically for aerodynamic flow fields involving wall bounded flows [18]. The SA model was considered suitable for this purpose due its proven capability of accurately modeling complex flows involving shock waves [19][20][21][22][23]. The CD GOX case was used for the GCI due to the known close correlation of a CD nozzle with analytical results [24].…”

Section: Grid Convergencementioning

confidence: 99%

Analysis of a Low-Angle Annular Expander Nozzle

Schomberg

Olsen

Doig

2015

Shock and Vibration

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An experimental and numerical analysis of a low-angle annular expander nozzle is presented to observe the variance in shock structure within the flow field. A RANS-based axisymmetric numerical model was used to evaluate flow characteristics and the model validated using experimental pressure readings and schlieren images. Results were compared with an equivalent converging-diverging nozzle to determine the capability of the wake region in varying the effective area of a low-angle design. Comparison of schlieren images confirmed that shock closure occurred in the expander nozzle, prohibiting the wake region from affecting the area ratio. The findings show that a low angle of deflection is inherently unable to influence the effective area of an annular supersonic nozzle design.

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“…Sketch of the venturi effect[73].Aside from changing and measuring the velocity in fluids, the venturi effect is used for mixing air and flammable gas in stoves, airbrushes, water aspirators that produce a partial vacuum using the kinetic energy from the faucet water pressure, atomizers that disperse perfume or spray paint, wine aerators used to infuse air into wine as it is poured into a glass, compressed air industrial vacuum cleaners, venturi scrubbers used to clean flue gas emissions, ventilators, airfoils moving close to the ground (ground effect[74]) amongst many other applications.Unlike conventional Bulb hydropower plants, the Moveable HEPP turbine module servers both for electricity generation and to control the spilled flow in the river. This arrangement considerably reduces the costs of building the dam due to the lack of a purposely built spillway, as in conventional dams.…”

mentioning

confidence: 99%

Dams with head increaser effect: Harnessing potential and kinetic power from rivers with large head and flow variation

Hunt

Byers

Prenner³

et al. 2018

Energy Conversion and Management

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There is an enormous untapped potential for hydropower generation in rivers with large head and high flow variation, currently not feasible for conventional hydropower dams. Conventional dams make use of the potential energy, but waste kinetic energy from spillage during periods of high flows. This article studies the possibility of harnessing energy from potential and kinetic energy from hydropower dams with large head and flow variation, analyses its potential, and shows possible technologies. Focus is given to a Moveable HydroElectric Power Plant (HEPP) system in which the turbine module can be adjusted according to the flow and water level in the river. During floods the exceeding flows can pass above and below the Moveable HEPP results in a sub-pressure environment after the turbine module, thereby reducing the dam's downstream head, increasing the pressure difference between the turbine inlet and outlet and the flow through the turbine, which increases the electricity generation of the dam. Dams with head increaser arrangement have been implemented in several dams in the 1930-1950s and now are regaining attention in Middle Europe. The main intention for its implementation is harnessing hydropower generation at run-of-river plants, with low-head, with a 20% to 30% cost reduction, lower flooded area at the dam site, the resulting evaporation and the impact on the aquatic fauna. A case study was performed with the proposal of the Aripuanã Moveable HEPP in the Madeira River with a 26 meters height dam and a generation capacity of 1,400 MW. The increase in generation with the head increaser effect is as high as 21%. The estimated potential for this technology in the Amazon region is 20 GW. Other potential locations are discussed in the article. Dams with head increaser effect have been successfully implemented and have the potential to become a major alternative for base load renewable energy in the future.

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Transonic and supersonic ground effect aerodynamics

Cited by 29 publications

References 78 publications

The effects of simplifications on isolated wheel aerodynamics

The effects of simplifications on isolated wheel aerodynamics

Analysis of a Low-Angle Annular Expander Nozzle

Dams with head increaser effect: Harnessing potential and kinetic power from rivers with large head and flow variation

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