This issue of the Aeronautical Journal celebrates the 50th anniversary of the foundation of the Honours Degree Course in Aeronautical Engineering at the Victoria University of Manchester. The following article therefore describes the aeronautical research and teaching activities of that university up to its recent amalgamation with the University of Manchester Institute of Science and Technology (UMIST) to form the present-day University of Manchester. This juncture provides a further justification for recording the Victoria University’s achievements.

Both the Victoria University and UMIST had their roots in the nineteenth century although, apart from the relatively brief period of the First World War, neither of them was particularly involved in aeronautics until after the Second World War. However, as Sections 6.0-10.0 seek to demonstrate, thereafter the Victoria University’s involvement became considerable. The preceding Sections describe the origins of the Victoria University and UMIST and, in the case of the former institution, the subsequent activities of its staff and graduates in engineering and mathematics which, although not always specifically aeronautical in content, nonetheless had a profound influence on the development of the aeronautical sciences.

The paper discusses the development and application activities within the Aero-Physics and Measurement Technology Laboratory at the University of Manchester on pressure sensitive paint and thermographic phosphor optical imaging systems for gas dynamic applications. It provides a brief review of the basic principles, fundamental theory, properties, chemical characteristics and bonding technologies associated with the two systems. A number of case studies are presented, which exhibit the range of applicability, limitations and potential for further development of the technologies.

Although macro-scale synthetic jets are well studied, our knowledge of the behaviour of micro-scale synthetic jets is still extremely limited due to the difficulty in performing detailed measurements with a desirable spatial solution. In the work presented in this paper, a PIV study of the characteristics of synthetic jets issued into quiescent air from orifices of 5mm and 0·5mm diameter respectively is undertaken. It is found that the vortex rollup is much weaker for the 0·5mm jets due to their low Stokes number which results in a near parabolic exit velocity profile. To ensure an appreciable vortex rollup that is desirable for effective flow control, the actuator has to be operated at much higher frequencies to ensure that the Stokes number is greater than a certain threshold value. Furthermore the study shows that the characteristics of synthetic jets of different scales are identical when the dimensionless stroke length (L), Stokes number (S) and Reynolds number (ReL) are the same. On the basis of these scaling parameters, the finding acquired from the studies on macro-scale actuators can be applicable to micro-scale actuators, which are more difficult to measure. Finally, it is also found that although the linear relationships between (L and ReL) and actuator operating conditions observed for macro-scale synthetic jets are no longer valid for micro-scale synthetic jets, the linear relationships between the dimensionless jet performance parameters and (L and ReL) still exist for micro-scale synthetic jets.

This paper presents an experimental investigation related to controlling the unsteady characteristics of the separated shear layers occurring over highly swept wings, and in particular focuses on application of synthetic jet actuators for modification of unsteady dynamic loading on the wing surface due to the phenomenon referred to as vortex breakdown (vortex burst).

In the post burst flow region the surface pressure measurements reveal the presence of certain characteristic spectral peaks that are thought to represent the presence of a spiralling filament of vorticity inside the expanded vortex that is known to be present in the burst flow over swept wings.

This paper details an investigation into how the use of an array of 18 discrete synthetic jet actuators, distributed along the leading edge of a delta wing with a 60° sweep angle, can be used to alter the spectral content of this unsteadiness and reduce the level of unsteady pressure found in the post-burst region toward the wing trailing edge by up to 40%.

Measurements of the surface pressure spectral distributions over the wing are presented together with PIV measurements of the vortex cross-section, conducted in the successive planes parallel to the wing trailing edge. Additional surface flow visualisation indicates that the effect of the actuators on the leading edge boundary layer is to induce local separation delays close to each actuator orifice, which introduce ‘ripples’ into the shear layer as it separates. The results obtained are used to formulate an interpretative hypothesis attempting to explain the mechanisms responsible for modification of the spectral content and the level of excitation measured on the wing surface.

The paper reviews the issue of cruise Mach number and addresses the benefits of operating subsonic commercial aircraft at speeds below the long-range cruise speed. The case considered is the flight of transport aircraft for flight segments up to 1,000nm. It is shown that the fuel burned is decreased by as much as 1·8% on a nominal 1,000nm stage length for operation around the long-range cruise Mach number, or below. This is achieved at a cost of a marginal delay on each flight segment (less than three minutes). The longer flight time is likely not to affect the daily operation of the aircraft. The fuel saving is compounded, because the gross take-off weight (GTOW) is recalculated to take into account the reduced fuel consumption at each flight segment. The analysis into the environmental benefits includes the reduction in,andemissions, and the heat released in the high atmosphere. Sensitivity analyses are carried out on the take-off weight, on the aerodynamic coefficients, on the transonic drag rise and the weight uncertainty. It is predicted that the optimal operation of the example aircraft over a nominal 1,000nm route can reduce the fuel consumption by as much as 150,000kg per year in comparison with an operation at the long-range Mach number. The aircraft model has a maximum take-off weight of 170,000kg and is powered by two GE CF6-80C2 engines.