V. M. Sazanovich

Laser beam pointing based on the backscattered aerosol beam. A model experiment

We present the experimental results of studying the possibility of compensating the misalignment of the axes of a laser beam, focused in an aerosol volume, and a receiving telescope from the shift of an image formed by a laser beam backscattered by aerosol particles of 0.5–0.6 μm. It is shown that the compensation can be carried out accurate to a few microradians via control of the position of the intensity distribution centroid of the image of the beam formed by the scattering volume.

Intensity fluctuations of a laser beam propagating through a supersonic flooded jet

The results of experimental researches of intensity fluctuations of a laser beam propagating through a supersonic flooded jet are presented. The laser beam propagates across the jet at various distances from a Vitoshinskii nozzle. The experiment was carried out in an Eiffel chamber at pressure ratios from 1.7 to 7 at two modes of the outflow of the jet: with the use of chevrons on the outlet nozzle and without chevrons. Dependencies of the dispersion and fluctuation spectra on pressure and distances from the nozzle are determined. The inner scale of turbulence is estimated.

Propagation of a laser beam reflected from a mirror in the turbulent medium

The paper presents an overview of the results of the authors investigations into the turbulence on the laser beam parameters propagating along double-passage of the correlated (monostatic) and uncorrelated (bistatic) paths. For the conditions of weak fluctuations we considered a variance and mean intensity on an axis of a wave by reflected from a diffraction- limited mirror when illuminating it by a quasi-spherical laser beam. The paper describes the results of the investigations of the turbulence affects on the formation by the receiving optical system of the image of a limited mirror reflector illuminated by a laser beam under conditions of strong fluctuations.

Analysis of 2D distribution of the frequency spectra of the flame model fire whirl

We investigated the fire whirl model obtained in a laboratory scale. The results of the IR camera application are presented. The spectral function of temporal fluctuations of the thermal imaging signal was calculated. We compared the spectral maximum with the rotational speed of the impeller. We have calculated the distribution of the spectral maxima in the flame of the fire whirl model. The probability of a correct determination of the rotation frequency of the torch from the spectral maximum depends essentially on the rotational speed.

Investigations of an acoustic field, generated by a supersonic flooded jet

The paper presents the results of experimental studies of the acoustic field generated by a supersonic flooded jet on the wind tunnel of the Vertical Jet Unit (VJU) ITAM SB RAS. The submerged jet came out vertically upward into a large enough room. Measurements are made by 9 microphones, which are placed on a ring with a radius of 265 mm, which moved vertically. The microphone inputs are installed at a radius of 235 mm (through 36°) symmetrically with respect to the axis of the jet. The time spectra of the acoustic field and the shape of the phase front at npr = 5 at heights from -50 to 495 mm are considered. The Mach number in the output section was equal to unity.

Investigation of the screech-tones excitation by the supersonic jet with laser transillumination method

We consider the applicability of laser transillumination method for the investigation of the screech-tones generation by the supersonic jet. Results of the experiments on parallel registration of the acoustic noise and laser radiation passed through the jet are discussed. The presence of responses at screech frequencies are found in the radiation spectra. Strong dependence of spectral amplitudes at screech frequencies from the sensing path shows high sensibility of laser sensing method for the selection of jet areas producing screech.

Altitude dependence of intensity fluctuations of the laser beam crosses the rotating flame

We investigated the vertical tornado flame obtained in a laboratory experiment. The results of laser sensing of the flame at several altitudes. Calculated spectral function of intensity fluctuations of a laser beam. For these functions are set depending altitude slopes in the high-frequency region.

Spectral composition of inhomogeneities of intensity of laser beam translucent the supersonic jet near the nozzle

The analysis of results of experiments on laser transillumination of the flooded supersonic jet on the wind tunnel of Institute of theoretical and applied mechanics SB RAS is fulfilled. The time spectra of fluctuations of the received power at different values of pressure in the chamber as well as the transformation of the spectra for the initial part of the jet with increasing distance from the nozzle are discussed. The change in the slope of the high-frequency part of the spectrum when lifting beam above the nozzle is demonstrated. Local maxima of the spectral density at frequencies corresponding to the discrete frequencies of acoustic tones generated by the stream are found.

Laboratory modeling of laser radiation propagation in a turbulent atmosphere under thermal self-action conditions

The results of experimental investigations on the model conditions of fluctuations of the diameter and shift of the center of gravity of laser beams propagating under conditions of developed turbulence and thermal self-action, as well as the simultaneous influence of these factors, are presented.

Experimental study of laser radiation propagation through a high-temperature swirling fire jet

The intensity fluctuations and image jitter of a laser beam passed through a swirling fire jet and the fluctuations of the intrinsic optical radiation of the flame are studied experimentally. A fire vortex was formed by swirling a gas flow emerging from a burning liquid with the use of revolving blades positioned under the reservoir with a liquid. The frequency spectra of fluctuations depending on the disc rotation speed are found.