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Contra‐rotating turbines offer reduced size, weight, and cooling requirements, compared to conventional co‐rotating machinery. In spite of the associated mechanical complexity, their aero‐thermal performance is superior to conventional turbines, not only due to the elimination of stator blade rows, but also because lower turning airfoils can be implemented as a result. The purpose of this paper is to present a methodology to determine the optimum velocity triangles of the turbine, together with a two‐dimensional design and optimization tool to minimize the blade unsteady force using radial basis function network, coupled to a genetic algorithm. The proposed design methodology is illustrated with the aerodynamic design of a contra‐rotating two‐axis turbine, which is able to deliver the power necessary to drive the LOX and LH2 pumps of an improved expander rocket engine.

This paper presents a methodology to determine the optimum velocity triangles of the turbine, together with a two dimensional design and optimization tool to minimize the blade unsteady force using radial basis function network, coupled to a genetic algorithm. The proposed design methodology is illustrated with the aerodynamic design of a contra‐rotating two‐axis turbine, which is able to deliver the power necessary to drive the LOX and LH2 pumps of an expander rocket engine, namely the Japanese LE‐5B.

The airfoil optimizer allows reductions in the downstream pressure distortion of 40 per cent. Consequently, the unsteady forces in the downstream blade row are minimized.

This paper presents to turbomachinery designers in liquid propulsion a novel tool to enhance the aerodynamic performance while reducing the unsteady forces on the blades.

A power unit for aircraft and the like comprising, an internal combustion engine, a variable pitch propeller, a supercharger for said engine, a compressor, a series of combustion chambers surrounding said compressor and connected to be supplied by said compressor, each of said combustion chambers terminating rearwardly in a propulsion jet, means for clutching said propeller to be driven by said engine, and drive means connecting said engine to the drive shafts of said supercharger and said compressor.

ANY aircraft development or innovation is news. Where it is specifically or related to powerplant it invariably becomes big news, with the potential of overseas users and national prestige uppermost in the mind. The recent keen competition for engine sales in the American market received due prominence, and with the three contestants all still in the field and sharing the largest order book in aeronautical history, the debut of this new generation of engines is eagerly awaited. Now when a substantial step forward in engine fundamentals and/or manufacturing techniques has been made, the tendency is to suppose that further advance will be small and some way off. But the fascination of the aerospace business is that there is yet no sign of slowing down in the rate of progress, and it is interesting to speculate on what may be around the corner and to ask, what next? A review of development over the last decade is illuminating and provides a lead to further discussion.

The characteristics and physical structure of the jet stream are described. The relationship of the jet stream to the general circulation in the atmosphere is illustrated by considering, first, the low level wind flow over the northern hemisphere and then the high level flow pattern (over 10,000 ft.). The seasonal change in position of jet streams and typical thermal and wind velocity cross‐sections are discussed. High altitude clear air turbulence is found to be associated with the periphery of the jet stream. The utilization of the jet‐stream as a wind‐aid in civil airline operations is discussed with reference to Pan‐American flights across the Atlantic and the Pacific.

OPERATING to increasingly severe noise and NOx emission levels and at the lowest Specific Fuel Consumption (SFC) attainable, current turbofan engines represent considerable advances in all respects on powerplants of only a few years ago. Nevertheless, the demand for even larger engines has meant that the major manufacturers are making considerable efforts to develop operating cycles and improved components to attain optimum performance for the foreseeable future.

THE rate of progress in civil aviation during the last decade has been largely determined by engine development. When the jet engine was first used in civil aircraft it was a means of obtaining higher speeds and improved passenger comfort at the expense of high fuel consumption and considerable annoyance to airport communities because of the noise. Significant improvements in fuel consumption and noise were obtained when the bypass concept was introduced, but there was a pause in development while the value of bypass ratio remained at about one. Another major forward step is being taken with the ‘new technology’ engines of bypass ratio five or more now under development, and it is timely to review the influence of these engines on the design of short range civil aircraft.

Turbofan engines will continue to dominate in both medium and long range airliners of the future according to Rolls‐Royce chief engineer of Advanced Projects John Sadler.

Under this heading are published regularly abstracts of all Reports and Memoranda of the Aeronautical Research Council, Reports and Technical Memoranda of the United States National Advisory Committee for Aeronautics and publications of other similar Research Bodies as issued

Held at the NEC Birmingham, the Aerospace Technology Exhibition and Conference was sponsored by the Aerospace Industries Division of the Institution of Mechanical Engineers together with the Institutions of Electrical Engineers and Electronic and Radio Engineers. It attracted papers on a variety of subjects and gave companies the opportunity to show a range of products, many of which were related to safety matters or maintenance programmes.

The purpose of this paper is to study the effects of aerodynamic excitations on the dynamic behavior of a helical two‐stage gear system.

The methodology consists of developing a wind turbine model including a helical two‐stage gear train having 21 DOFs.

The results of this paper show that the dynamic behavior of the speed‐up gearbox inside the wind turbine is affected by various degrees of flexibility at different frequencies.

The aerodynamic forces are calculated by two main methods, the first is the actuator disc theory and the second is the Blade‐Element Method. Some correction functions are applied, such as the tip‐root loss functions and the Glauert correction factor. The convergence of the induction factors permits to increase the precision of predictions. Finally, the generator side is modeled by a simplified electric schematic based on steady state model.