Specifics of the aircraft power plant inlet device shape effect on the induced vortexes intensity

Аuthors

Aisin A. K.^*, Achekin A. A., Preis A. A.

Air force academy named after professor N.E. Zhukovskii and Y.A. Gagarin, Voronezh, Russia

*e-mail: aisin_alex@mail.ru

Abstract

The aircraft power plant operation on the ground is associated with the intense vortices forming between the inlet device and the airfield surface. This factor affects negatively the power plant operability. It reduces gas-dynamic stability margin of the engine and creates favorable conditions for the foreign objects suction into the air intake.
The vortex formation mechanism has been studied in sufficient detail. Initially, the vortex intensity depends on the operating parameters and layout of the inlet device. Significant parameters, affecting the vortex intensity are the airflow, diameter, height above the surface, bevel angle, layout, and feeding windows availability.

However, the degree of geometric shape effect of the inlet device has not been sufficiently studied, although initially it namely is that determines the vortex intensity potential for a particular power plant.
The first stage of experimental studies of the inlet device geometry impact on the intensity of the vortex induced by it was determining for the following shapes of the inlet sections at different heights:
– square section with a bevel;
– square section without bevel;
– round section;
– semicircular section with a lip up;
– semicircular section with a lip down;
– rhomboid section.
At the second stage, the problem was reduced to studying the ratio of the input device height to the length of its lower (upper) edge A_ID = A/B for different heights of the input device.
As the result of the research, the following inferences were drawn:
– the entrance section geometry of the inlet device cannot affect the formation vortex intensity under it.
– for the same height of the geometric (energy) center location of the inlet device, the vortex flows of greater intensity are being induced by the inlet device, with a “bevel” and the lower edge located closer to the surface.

Keywords:

experimental studies of the vortex intensity, vortex intensity criterion, maximum horizontal velocity of the wall-adjacent flow, air intake (inlet device) geometric shape, inlet device mounting height, air intake geometric (energy) center, bevel angle of the air intake inlet cross-section, fighter air intake

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