This Thesis has endorsed employing a novel indraft configuration for a severely spatially and financially constrained wind tunnel aimed at undergraduate and postgraduate aeronautical and automotive instruction. The novel horseshoe indraft configuration employed may be considered to either bend a traditional open circuit or remove corners 3 and 4 from a traditional closed circuit. By connecting the inlet and exit to atmosphere the new configuration prevents pressure loading of the surrounding building; eliminates the problem of exhausting a jet within a laboratory; and eliminates costs associated with a heat exchanger. The modest budget (£350,000) is commensurate with the financial means of a University or small enterprise. Aerodynamic performance data suggests future designers should not shy away from an indraft tunnel by default: Velocity uniformity in the working area of jet has been shown to vary by less than 0.3% of the mean in the presence of ambient gusts up to 11.5% of the test velocity. Lift and drag coefficients derived from a 27% scale Davis automotive model (5.9% frontal area blockage) repeated to 6 units (0.6%) and 2 units (0.2%) respectively in the presence of ambient gusts up to 13% of the test velocity. Axial turbulence intensity was measured to be in the region of 0.15% (negligible ambient gusts) and 0.35% (ambient gusts up to 16% of the test velocity). This data compares favourably to that for the significantly larger NASA Ames 80ft x 120ft open circuit wind tunnel. Maximum test section velocity has been shown to be in excess of the desired 40m/s. The test section boundary layer closely follows the profile for a 1/7th power law turbulent boundary layer, which suggests the contraction is free from separation. This Thesis contributes to the body of knowledge by publishing performance data for a new type of wind tunnel configuration. It also augments existing design guidelines and rules of thumb by providing a complete reference point (including design flowcharts) for the design of comparable low speed wind tunnels. The Thesis offers the following specific conclusions and implications: Screens: Whilst the inlet filer mesh is effective at damping ambient gusts it suffers the worst correlation to the governing equations (significant under prediction of loss), likely due to wire-wake coalescence. This highlights the importance of performing pipe rig tests for screens with open areas significantly less than 57%. Safety screen loss was under-predicted (assumed drag coefficient, CD of 1.0 due to treatment as isolated wires). Whilst measurements suggest a CD of ~1.25 designers are advised to conduct pipe rig tests. Contraction: To allow pressure gradients to decay prior to the working section, it is advised that the parallel duct at end of the contraction be 1 hydraulic diameter rather than the 1 hydraulic radius proposed by the major texts. Working section: To allow for model wake recovery (and hence reduce the effect of non-uniformity on the downstream diffuser), a working section length-to-diameter ratio of 2.5 is suggested rather than 2 proposed by the established texts. Additionally, the static ports of tunnel pitot-static should be at least 0.55 hydraulic diameters upstream of the model leading edge to position them away from the static pressure signature of the model. Diffusers: Whilst the safety screen would ideally have to be removed to prove the hypothesis - it is suggested that turbulent mixing aft of the safety screen (located at the end of the working section) appears to offer a ~10% Cpr improvement to the first diffuser. Corner cascades: Whilst the established texts focus on corner loss coefficient (KL) this Thesis has shown that KL should not be the sole metric used to select the space-to-chord ratio (s/c) of corner cascades. Uniformity far downstream of a test cascade has been shown to improve with more closely spaced vanes (s/c of 0.190 rather than 0.237) despite KL being similar. Improvements to inlet boundary layer quality have also been shown to reduce KL. Fan: The fan static pressure rise was measured to be less than predicted due to smaller than expected leakage losses. A leakage loss of 2.5% is therefore proposed rather than the 10% suggested by the major texts.

CFD and wind tunnel simulations are complementary due to their inherent limitations. Wind tunnel tests apply to any hypothesis, but are limited by the tunnel wall interference/blockage, the model details, and even the distortion of the model. CFD are not limited in any of these ways, but limited in speed and memory and the lack of determinate set of equations. Theoretically, CFD can provide an assessment of any problem in fluid dynamics (Direct Numerical Simulation), but the requirements of speed and memory are far from being met presently, or even in the foreseeable future. Of necessity, present CFD applications, however, employ a turbulence model, which limits its application due to the problems in accuracy and reliability. Given the power of CFD however, the work contained herein makes use of the advantages of CFD and also the wind tunnel, to form a powerful facility for aerodynamic test, i.e., CFD was used to complement and enhance the wind tunnel test, so producing an integrated test facility. A very important aspect in this work is that CFD was used to investigate the blockage correction for wind tunnel tests. By using CFD, the blockage correction could be made directly, in terms of representing the test model and tunnel walls in high fidelity. Meanwhile, the effect of support system on the test model was also investigated by CFD. The numerical results showed significant effect of the strut on the test model in the Argyll Wind Tunnel (Glasgow University), and an interesting result showed that different positions of support system had different effects. This research aimed to utilise CFD to support wind tunnel testing, and its ultimate purpose is to form a powerful facility for aerodynamic test by combining CFD and wind tunnel. The contributions are summarised as follows: The calibrations of wind tunnel by CFD simulations; A proposed improvement for moving belt system by CFD tools; Blockage correction of wind tunnel by CFD method; and The confirmation of CFD results by wind tunnel model test.