Environmental disturbance aerodynamic parameters registration while object moving
Radiolocation and radio navigation
Аuthors, *, **, ***
Moscow Aviation Institute (National Research University), 4, Volokolamskoe shosse, Moscow, А-80, GSP-3, 125993, Russia
A number of engineering problems associated with the object movement in the air require the information on the air state right behind the moving object. For example, while large aircraft takeoff we need to know the period of turbulence existence to impose restrictions on the time interval between two airplanes takeoff. For airplanes and helicopters landing we need air-cushion size evaluation to work out requirements on minimum overflight height over buildings and constructions in the entry area. The turbulence presence is of great importance also during aerial refueling operations.
At the instant of beam breaking, one can observe strong pulses of positive and negative polarities, caused by recharging processes of capacitances in the circuit. After the end of breaking, the beam deflects to the areas with bigger pressure and oscillates in the region of red, blue and green zones. Approximately after 20 ms the beam returns to the yellow zone region, and oscillates with damped amplitude to the level, existing prior to beam breaking.
The existing research techniques do not allow registering the fast parameters variation and non-uniformity fluctuations in the air, and yield the averaged picture at a certain time interval.
The developed facilities allow registering the variations in medium density and disturbances behind a moving object in the form time function with resolution less than 0.1 ms. The paper presents the angle curves of the laser beam passing through disturbed environment fluctuations after four-channel square-shaped photoelectric detector.
The emitter (laser diode) is set at the side of an automobile road, and its beam is directed perpendicularly to automobile movement at the height of 1 m. And photodetector is set at the other side of the road. Its output signals were fed to the computer through ADC, where they were registered and processed. After an automobile crossed the beam, the occurring in the air turbulence and disturbances caused the beam refraction and its movement along the four-channel photodetector aperture. The current beam position was determined according to signal levels in the photodetector channels relationship.
The presented system allows performing analysis of pressure transmitted fluctuations in the air, occurring in response to the moving object, evaluate their amplitudes and frequencies, transient time. It can be useful for aerodynamic performance studies of the objects of various shapes.
Keywords:atmosphere analysis, laser, four-channel photoelectric receiver, analog-to-digital converter
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