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A design philosophy for low Reynolds number airfoils that judiciously combines the tailoring of the airfoil pressure distribution using a transition ramp with the use of boundary-layer trips is presented. Three airfoils with systematic changes to the shape of the transition ramp have been designed to study the effect of trips on the airfoil performance. The airfoils were wind-tunnel tested with various trip locations and at Reynolds numbers of 100,000 and 300,000 to assess the effectiveness of the design philosophy. The results show that the design philosophy was successfully used in integrating a boundary-layertrip from the outset in the airfoil design process. For the Reynolds numbers and the range of airfoil shapes considered, however, airfoils designed with trips do not hold any clear advantage over airfoils designed for good performance in the clean condition.

The present work focused on the full characterisation of a blended-wing-body UAV airframe recurring to a wind tunnel testing approach known as Modern Design of Experiments (MDOE). The results of this project are going to be applied in the design of a new control system for the aircraft. The tests were completed in a low-speed wind tunnel facility at Council for Scientific and Industrial Research (CSIR) in Pretoria, South Africa. The model was prepared for the wind tunnel tests, which included structural analysis, reinforcement and instrumentation. As part of the MDOE technique, the design of experiment of the test program was considered and analysed prior to the testing itself. The tests were then executed and the data collected and analysed. The final results consist in 12 models that fit the data for the six aerodynamic responses (2 per response): Lift, Drag, Side Force, Pitching Moment, Rolling Moment and Yawing Moment coefficients. All the models were extensively analysed using confirmation points. An example of significant systematic variation for the drag coefficients was detected and corrected. A study of the bias and tolerance trade-off resulting from the data correction for the wind tunnel influences was also conducted.

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A methodology for the inverse design of nonlifting axisymmetric and nonaxisymmetric bodies in incompressible flow is presented. In this method, an inverse design approach based on conformal mapping is used to design a set of airfoils in isolation. These airfoils are then assembled into a three-dimensional body and the flow over the body is calculated using a panel method. The inverse design parameters for the isolated airfoils are adjusted by a multidimensional nonlinear solver to achieve the desired aerodynamic properties on the three-dimensional body. The method can be used with fairly complex geometries, such as bodies in the presence of a wing or keel. The suitability and performance of several numerical schemes are compared in the paper. Several examples are presented that demonstrate the flexibility of the design method when applied to various representative design problems and they also show the ability of the method to match a known velocity distribution. Nomenclature A = area B = approximate Jacobian c = chord length c i = control airfoil F = vector of functional relations f i = functional relations to be zeroed h = surface displacement J = Jacobian matrix _ m = mass-flux n = dimension of nonlinear system n = surface normal Re = Reynolds number s = arc length s i = control sectioñ s = arc length relative to beginning of section u = normal velocity u t = transpiration velocity V 1 = freestream velocity _ v = volume flux v i = relative velocity along a splined segment x i = unknown variables x = vector of unknown variables x = correction vector = angle of attack, deg = segment design angle of attack = arc limit = arc limit relative to beginning of segment = source strength V = velocity difference over a segment normalized by the freestream velocity Subscripts i = segment number on an airfoil or the equivalent segment of the body cross-section p = unperturbed surface panel t = transpiration