This paper describes the development of a generic aircraft systems dispatch reliability design methodology (ASDRDM) that has been developed for use during early phases of the aircraft systems design process.

The methodology incorporates prediction of both reliability and maintainability through the aircraft design hierarchy, down to component level. It can be applied at the early design stage, but can also be used for advanced design phases and can use generic or actual failure rate and mean time to repair data. It allows designers to modify system architectures and component reliability and maintainability characteristics. The paper shows the validation that has been performed, and its use is demonstrated by a case-study.

Flow interaction of three different jet configurations ejecting air from a flat plate into a supersonic cross flow were investigated experimentally and numerically. The test conditions encompassed a jet pressure ratio of Poj, P∞ = 100 at a Mach number of M∞ = 5 and Reynolds number of about Re∞ = 25 × 106 based on the length of the flat plate. The investigated test cases are: a) single jet; b) four jets positioned in-line in main flow direction; c) four jets positioned side-by-side in spanwise direction. The prediction of the overall flow phenomena as occurring within the interaction area was in fair agreement with the experiments, although quantitatively differences occur that will be discussed in the paper.

The results of the comparison are presented and the experimental data are used to validate the applied code.

The force measurements were conducted in low speed wind tunnel to investigate the effects of the scale, shape and the installation type of Gurney flap on a forward-swept aircraft model. The results indicated that both rectangular and triangular Gurney flaps can enhance the lift coefficient of the model tested, but with a little decrease of stall angle from 38° to 36°. The lift and drag coefficients increased with the Gurney flap scales. Meanwhile, the triangular Gurney flap can improve the aerodynamic performance more effectively when its high side is located near the wing root than the reverse installation with the low side near the wing root and the high side near the wing tip. Additionally, for the same Gurney flap, the model with smaller forward-swept angle can generate higher lift-enhancement in comparison with the larger forward-swept angle model.

Minimum drag shapes of given length and base area are investigated for hypersonic flow using both Newtonian impact theory and free molecular flow theory. The drag of Newton’s minimum drag body, which has previously been evaluated by numerical means, is derived as an analytic expression. The analytical results are applicable to a range of local pressure laws allowing minimum drag shapes obtained using impact theory to be directly compared with low density flow equivalents using free molecular flow. The low density shapes are found to have larger blunt regions at the nose and significantly larger drag coefficients. For free molecular flow the drag varies with the surface reflection characteristics. As the fraction of diffuse reflection at the surface increases, the drag increases and the sensitivity of the drag to changes in the minimum drag shape is reduced.

The integration of multidisciplinary data is key to supporting decisions during the development of aerospace products. Multidimensional metamodels can be automatically constructed using limited experimental or numerical data, including data from heterogeneous sources. Recent progress in multidimensional response surface technology, for example, provides the ability to interpolate between sparse data points in a multidimensional parameter space. These analytical representations act as surrogates that are based on and complement higher fidelity models and/or experiments, and can include technical data from multiple fidelity levels and multiple disciplines. Most importantly, these representations can be constructed on-the-fly and are cumulatively enriched as more data become available. The purpose of the present paper is to highlight applications of these cumulative global metamodels (CGM), their ease of construction, and the role they can play in aerospace integration. A simple metamodel implementation based on a radial basis function network is presented. This model generalises multidimensional data while simultaneously furnishing an estimate of the uncertainty on the prediction. Four examples are discussed. The first two illustrate the efficiency of surrogate-based design/optimisation. The third applies CGM concepts to a data fusion application. The last example is used to visualise extrapolation uncertainty, based on computational fluid dynamics data.

PIV measurements in the near-field region of a jet flow emanating from a round synthetic jet actuator into quiescent air were conducted over a range of operating conditions. The primary purpose of this work was to investigate the nature of synthetic jets at different operating conditions and to examine the jet flow parameters that dictate the behaviour of synthetic jet actuators. The effects of varying diaphragm displacement and oscillatory frequency for fixed actuator geometry were studied. It was observed that the characteristics of synthetic jets are largely determined by the Reynolds number and stroke length. An increase in the former is observed to increase the strength of consecutive vortex rings that compose a synthetic jet, whereas an increase in the latter results in an increase in relative vortex ring spacing and for further increases in stroke length, shedding of secondary vortices. Correlations were also made between the operating parameters and the performance parameters most effective for flow control and which therefore determine the impact of a synthetic jet on an external flow. Relations of time-averaged dimensionless mass flux, momentum flux and circulation with the jet flow conditions were established and found to widely support an analytical performance prediction model described in this paper. It is anticipated that the experimental data obtained in this study will also contribute towards providing a PIV database for macro-scale synthetic jet actuators.