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There has been some speculation anions STOL aircraft designers (hat a net increase in lift might be realized from a combination of blown flap and slip‐stream deflexion. A recent wind tunnel investigation confirms the speculation for large flap deflexions. At small flap deflexions, however, the lift gained by the combination is less than the sum of the separate contributions. The effect at medium flap deflexion is dependent on the strength of the slipstream. These results should be applicable to most configurations with a blown plain flap in the slipstream behind the propellers.

This paper aims to investigate the effect of different wing height layouts on the aerodynamic performance and flow structure of high-speed train, in a train-wing coupling method with multiple tandem wings installed on the train roof.

The improved delayed detached eddy simulation method based on shear stress transport k- ω turbulence model has been used to conduct computational fluid dynamics simulation on the train with three different wing height layouts, at a Reynolds number of 2.8 × 10⁶. The accuracy of the numerical method has been validated by wind tunnel experiments.

The wing height layout has a significant effect on the lift, while its influence on the drag is weak. There are three distinctive vortex structures in the flow field: wingtip vortex, train body vortex and pillar vortex, which are influenced by the variation in wing height layout. The incremental wing layout reduces the mixing and merging between vortexes in the flow field, weakening the vorticity and turbulence intensity. This enhances the pressure difference between the upper and lower surfaces of both the train and wings, thereby increasing the overall lift. Simultaneously, it reduces the slipstream velocity at platform and trackside heights.

This paper contributes to understanding the aerodynamic characteristics and flow structure of a high-speed train coupled with wings. It provides a reference for the design aiming to achieve equivalent weight reduction through aerodynamic lift synergy in trains.

SYSTEMATIC experiments carried out by the Dornier‐Werke for several years (for the purpose of investigating flight properties and the quantities of importance for flight performance) included, during 1935, point‐to‐point measurement of the downwash field in front of the tail unit of the Do 17, using twin tube pressure recorders. These flight measurements showed that the stability components of the two halves of the tail plane are not the same on account of the different downwash components produced by rotation of the slipstream. The conclusion that the stability of the aeroplane could be raised by symmetrical arrangement of the airscrews, in accordance with the more favourable starboard side, was well founded, and it was soon recognized that this precaution, in conjunction with the other well‐known advantages of symmetrical direction of rotation of the engine units, is one of the most effective methods for improving the flying properties of two‐ and four‐engined aircraft. This knowledge, which in the meanwhile had been confirmed in various places by wind tunnel tests induced the Dornier‐Werke to generally introduce counterrotating power plants for twin‐engined aircraft.

The aerodynamic differences between the head car (HC) and tail car (TC) of a high-speed maglev train are significant, resulting in control difficulties and safety challenges in operation. The arch structure has a significant effect on the improvement of the aerodynamic lift of the HC and TC of the maglev train. Therefore, this study aims to investigate the effect of a streamlined arch structure on the aerodynamic performance of a 600 km/h maglev train.

Three typical streamlined arch structures for maglev trains are selected, i.e. single-arch, double-arch and triple-arch maglev trains. The vortex structure, pressure of train surface, boundary layer, slipstream and aerodynamic forces of the maglev trains with different arch structures are compared by adopting improved delayed detached eddy simulation numerical calculation method. The effects of the arch structures on the aerodynamic performance of the maglev train are analyzed.

The dynamic topological structure of the wake flow shows that a change in arch structure can reduce the vortex size in the wake region; the vortex size with double-arch and triple-arch maglev trains is reduced by 15.9% and 23%, respectively, compared with a single-arch maglev train. The peak slipstream decreases with an increase in arch structures; double-arch and triple-arch maglev trains reduce it by 8.89% and 16.67%, respectively, compared with a single-arch maglev train. The aerodynamic force indicates that arch structures improve the lift imbalance between the HC and TC of a maglev train; double-arch and triple-arch maglev trains improve it by 22.4% and 36.8%, respectively, compared to a single-arch maglev train.

This study compares the effects of a streamlined arch structure on a maglev train and its surrounding flow field. The results of the study provide data support for the design and safe operation of high-speed maglev trains.

The purpose of the paper is to build a real-time integrated turboprop take-off model which fully takes the interaction between diverse parts of aircraft into consideration. Turboprops have the advantage of short take-off distance derived from propeller-wing interaction. Traditional turboprop take-off model is inappropriate because interactions between diverse parts of aircrafts are not fully considered or longer calculation time is required. To make full use of the advantage of short take-off distance, a real-time integrated take-off model is needed for analysing flight performance and developing an integrated propeller-engine-aircraft control system.

A new integrated three-degree-of-freedom take-off model is developed, which takes a modified propeller model, a wing model and the predominant propeller-wing interaction into account. The propeller model, based on strip theory, overcomes the shortage that the strip theory does not work if the angle of propeller axis and inflow velocity is non-zero. The wing model uses the lifting line method. The proposed propeller-wing interaction model simplifies the complex propeller-wing flow field. Simulations of ATR42 take-off model are conducted in the following three modes: propeller-wing interaction is ignored; influence of propeller on wing is considered only; and propeller-wing interaction is considered.

Comparison of take-off distances and flight parameters shows that propeller-wing interaction has a vital impact on take-off distance and flight parameters of turboprops.

The real-time integrated take-off model provides time-history flight parameters, which plays an important role in an integrated propeller-engine-aircraft control system to analyse and improve flight performance.

The real-time integrated take-off model is more precise because propeller-wing interaction is considered. Each calculation step costs less than 20 ms, which meets real-time calculation requirements. The modified propeller model overcomes the shortage of strip theory.

AT low forward speeds the slipstream from a helicopter rotor is substantially downwards in direction and will cause a drag force to be generated on any body immersed in it, the drag acting in the direction of the slipstream. In most performance methods the effect of this vertical drag is ignored, bat it cart in fact substantially modify calculated performance, being equivalent to a weight increase of over 10 per cent even on some single rotor designs. The basic parameter is the equivalent flat plate area (area of body drag coefficient) which is immersed in the slipstream, and this is expressed as a ratio of the rotor disk area, i.e. ACD/πR2.

THE mathematical theory of longitudinal stability appears to have been adequate to explain the salient features of the behaviour of aeroplanes in longitudinal motion. In general the provision of a stable slope to the static pitching moment curve has been found in practice to fulfil all requirements, and although increasing oscillations do on occasion occur, they are on the whole surprisingly rare. The reasons for this are fairly well recognised and are briefly indicated in what follows. There is little doubt, however, that the designers' principal difficulties centre round the complex interferences between the wings and the tailplane, particularly with the air‐screw running. The downwash from the centre section in many machines, even with no engine on, is quite unpredictable in the present state of knowledge, and the calculation of the downwash due to the slipstream has not yet been successfully made even in the simplest cases. Some attempt is here made to summarise the present position.

ALL the theories relating to the nature of the airflow through a helicopter rotor which have been reviewed in the first three parts of this paper relate to vertical velocities only; that is, to the downwards acceleration of the air whereby rotor thrust is generated. But since a practical rotor blade also experiences in‐plane forces it is evident that in‐plane movements of the air in the slipstream must also occur. In point of fact the slipstream rotation behind the propeller of a single engined aeroplane of conventional design is an important factor in its design, particularly when considering take‐off conditions.

In an aircraft providing a finite slipstream at each side thereof, upper and lower wings having cavities and trailing edge apertures communicating with the respective cavities, flaps movably connected to the wings, the flaps when fully retracted closing the apertures and when deflected downward exposing the apertures to the atmosphere, blower means, and ducting leading from the blower means rearward to the apertures, whereby, when the flaps are deflected downward, the blower means may move air through the apertures to attenuate turbulence at the trailing edges, the wings being negatively staggered to such an extent that the slipstream directed downward by the upper flap will not interfere with the lower slipstream.

DEAR SIR,—I read with much interest Mr. J. H. Crowe's article on Longitudinal Stability, which was published in the March issue of AIRCRAFT ENGINEERING. It forms a useful summary of present‐day knowledge on the glider stability problem, but is rather misleading in the section devoted to the effects of slipstream.