K.J. Craig

Computational Study of Blowing on Delta Wings at High Alpha

In this study, the flowfield produced by tangential leading-edge blowing on a rounded leading-edge 60-deg delta wing at high angle of attack is investigated computationally by solving the thin-layer Navier-Stokes equations. Steady-state flowHelds are calculated for various angles of attack, with and without the presence of tangential leading-edge blowing. The numerical grid is generated using algebraic grid generation and various interpolation and blending techniques. The jet emanates from a slot with linearly varying thickness, and is introduced into the flowfield using the concept of an actuator plane, thereby not requiring resolution of the jet slot geometry. The Baldwin-Lomax algebraic turbulence model is used to provide turbulent closure. The computational results are compared with those of experiments. The effectiveness of blowing as a rolling moment control mechanism to extend the envelope of controllabili ty is illustrated at different angles of attack. The saturation effect of increased blowing is captured well in the computations. Control reversal noted in similar experimental studies is also observed in the computations.

Continuous cast width control using a data mining approach

Abstract Twelve per cent chrome ferritic (non-stabilised) stainless steel cast at the continuous caster at Columbus Stainless exhibited notable differences in the width change between consecutive heats. The reason for these differences is related to the fact that the steel is in a dual phase region between austenite and ferrite during the solidification stages of the continuous casting process. A model was developed and is currently used as a production tool to predict the width change of a 12% chrome ferritic heat before it is cast based on heat composition. The strand width is altered based on the model predictions by changing the secondary cooling pattern. It was uncertain if the current model is the best suited for this application and a study was carried out using different but more advanced data mining techniques in an attempt to improve the existing model. It was found that advanced data mining techniques could not improve the original rule based model.

Modifying Low-Drag Bodies to Generate Lift: A Computational Study

Experimental work has shown that the flowfield around a wing-body configuration can be successfully modified with a short Kutta edge tail, so named because, by controlling the rear stagnation point...

Numerical Investigation of the Aerodynamic Performance for an Alternative Wing–Body–Tail Configuration

It is common for new aircraft configuration proposals to include some kind of lifting body. The reduction in fuselage–wing interference drag, in principle, improves span efficiency and hence allows...

Optimization of insulation of a linear Fresnel collector

This study presents a simulation based optimization study of insulation around the cavity receiver of a Linear Fresnel Collector. This optimization study focuses on minimizing heat losses from a cavity receiver (maximizing plant thermal efficiency), while minimizing insulation cross-sectional area (minimizing material cost and cavity dead load), which leads to a cheaper and thermally more efficient LFC cavity receiver.This study presents a simulation based optimization study of insulation around the cavity receiver of a Linear Fresnel Collector. This optimization study focuses on minimizing heat losses from a cavity receiver (maximizing plant thermal efficiency), while minimizing insulation cross-sectional area (minimizing material cost and cavity dead load), which leads to a cheaper and thermally more efficient LFC cavity receiver.

Combined thermal, optical and economic optimization of a linear Fresnel collector

This study presents a simulation based optimization study of a Linear Fresnel Collector with a trapezoidal multi tube cavity receiver. The study focuses on harvesting the maximum daily solar energy (maximizing plant optical efficiency throughout a summer’s day), while minimizing plant thermal heat loss (maximizing plant thermal efficiency), as well as plant cost (the economic optimization of the plant), which leads to the generation of cheaper solar electricity from an LFC plant.This study presents a simulation based optimization study of a Linear Fresnel Collector with a trapezoidal multi tube cavity receiver. The study focuses on harvesting the maximum daily solar energy (maximizing plant optical efficiency throughout a summer’s day), while minimizing plant thermal heat loss (maximizing plant thermal efficiency), as well as plant cost (the economic optimization of the plant), which leads to the generation of cheaper solar electricity from an LFC plant.

Combining ray tracing and CFD in the thermal analysis of a parabolic dish tubular cavity receiver

This paper describes the numerical evaluation of a tubular receiver used in a dish Brayton cycle. In previous work considering the use of Computational Fluid Dynamics (CFD) to perform the calculation of the absorbed radiation from the parabolic dish into the cavity as well as the resulting conjugate heat transfer, it was shown that an axi-symmetric model of the dish and receiver absorbing surfaces was useful in reducing the computational cost required for a full 3-D discrete ordinates solution, but concerns remained about its accuracy. To increase the accuracy, the Monte Carlo ray tracer SolTrace is used to perform the calculation of the absorbed radiation profile to be used in the conjugate heat transfer CFD simulation. The paper describes an approach for incorporating a complex geometry like a tubular receiver generated using CFD software into SolTrace. The results illustrate the variation of CFD mesh density that translates into the number of elements in SolTrace as well as the number of rays used in t...

Influence of the gap size on the wind loading on heliostats

Generally built in desert areas, heliostat fields undergo various wind loading conditions. An ANSYS Fluent CFD model of an isolated heliostat in worst-case orientation for the drag force is realized via numerical simulations using the realizable k-e turbulence model. This paper focuses on the gap width between the panels and its influence on the wind loading that heliostats are subjected to. An atmospheric boundary layer profile is generated based on a wind tunnel experiment. For a heliostat in upright and tilted orientations with the wind angle being zero degrees, the gap width is varied and the force and moment coefficients are calculated. In the range tested, all the coefficients globally increase with the widening of the gaps.