This paper discusses the evolution of airpower and the ever-increasing component of stealth technology in dictating warfare, based on the need felt in the literature to integrate and place them in the right perspective. Hence, the role of stealth aircraft and the dominance of all aspects of stealth technology, especially in recent conflicts, are reviewed. The integration of the fundamental aspects of stealth technology, through its classification, types of aircraft signatures: especially radar, infrared, and visual signatures, their sources of origin, modelling techniques, and methods of signature reduction are discussed. Due to the increasing importance of infrared signatures relative to radar signatures, infrared signatures are also closely examined and analysed. Hence, the lock-on and surveillance ranges of infrared detectors are compared. Future projections in stealth technology, especially based on the role of anti-stealth technologies, are also elaborated.

A computational fluid dynamics (CFD) model of three different axisymmetric convergent nozzle designs was created. Two of the nozzles had trailing-edge modifications (TEMs), which consisted of four regularly-spaced tooth-gap castellation pairs. One of the castellated nozzles had a divergent gap profile (regular castellated) and the other had a convergent gap profile (convergent-chamfered castellated). The remaining plain nozzle had no castellations.

Calculated CFD results were examined at a nozzle pressure ratio (NPR) of 6·5 in the near field of the regular castellated and convergent-chamfered castellated nozzles. Jet fluid was seen to be ejected radially from the jet core through the gaps between the castellations at the nozzle exit plane. Contra-rotating streamwise vortices were seen to develop at the interface between the gap and castellation. These were of the sense that acts to pump jet fluid out in the plane of the gap and entrain ambient fluid in the plane of the tooth. Peak increases of approximately 45% in non-dimensional mass flow rate over the plain nozzle were seen.

The ejections from the four-tooth regular-castellated nozzles extended far enough radially that they became detached from the main jet core. The contra-rotating vortices moved closer together with downstream distance reinforcing the pumping action between them. The jet ejections from the convergent-chamfered castellated nozzles did not extend far enough radially to detach from the main core (at the NPR tested) nor did the contra-rotating vortices move significantly closer together. Peak increases of approximately 45% and 25% (for the regular-castellated and convergent-chamfered castellated nozzles respectively) in non-dimensional mass flow rate over the plain nozzle were seen.

The strength of the contra-rotating vortices had dropped by two orders of magnitude at five nozzle diameters downstream from the exit plane. This suggested that the extent of fluid ejection may be more important than the initial strength of the vortices (although stronger vortices may help to eject fluid further out radially). Thus, configurations of nozzle geometry which cause the resulting streamwise vortices to interact favourably in ejecting fluid, would be desirable.

Although many researchers, from a number of industries, have studied the aerodynamics of ground effect conditions, published research remains inconclusive. Published results are frequently found to conflict and modeling procedures (in both computational and experimental situations) vary. In this paper, existing research is reviewed and the methods used in obtaining the results are compared. Possible causes for the discrepancies in the published work are outlined, including the inappropriate specifications of boundary conditions and the neglect of viscosity in some computational analyses. Computational and experimental analyses are then performed to determine if these identified areas do cause inconsistencies in results and to also determine accurate simulation procedures.

Experiments assessing the effectiveness of passive control involving a porous surface and cavity underneath for reducing the level of surface pressure fluctuations in reattaching flows are reported. Measurements are made on a generic axisymmetric body, representative of a launch vehicle configuration, in the Mach number range of 0·8 to 1·2. The measurements consist of distributions of mean surface pressure and unsteady surface pressure fluctuations in the boat-tail separated region. The passive control significantly reduces the peak surface pressure fluctuations in the reattachment zone, even in the absence of a strong shock wave. The spectra of pressure fluctuations reveal that with passive control the energy is appreciably reduced over a wide range of frequencies.

Computational fluid dynamics (CFD) tools are an integral part of the processes within design and performance assessment offices in the aerospace industry. As timescales from initial concept to design-freeze become shorter, there is an increasing need for the CFD process to be timely and cost effective and for confidence in the predictive capability of the CFD tool to be high. Only in this way will the impact of CFD be maximised. The CFD software development and support team plays a key role in achieving this goal. This paper describes how the team at ARA has met the challenge of delivering to industry what it requires in terms of both the CFD tools and the people who supply them. The qualities needed to do this extend beyond the ability to achieve technical advancement, although prime emphasis is still placed on this aspect. In particular, the importance of developing a close relationship between CFD team and end user — an integrated team approach — is stressed. This leads to a precise and unambiguous understanding of customer needs and the delivery of the required product and its maintenance. The demonstration of recent technical achievements and the discussion of supporting team attributes exemplify these points.