Pooplavski S.V.   Boiko V.M.  

The complex of optical methods for study of gas-liquid jets

Reporter: Pooplavski S.V.

The study of the dispersion of liquids and the dynamics of sprays in the gradient gas flows is a fundamental task within the framework of the problem of interfacial heat and mass and energy exchange in nonequilibrium heterogeneous systems. Generation of liquid sprays is used in various technological processes in the chemical industry, energy, aviation and rocket engines, and information on the physical mechanisms of aerodynamic fragmentation of the fluids is critically required to create efficient nozzles and injectors.
The aim of this work was to create a complex of optical methods for studying the dispersion and the dynamics of liquids in high speed gas jets. The efficient methodology to obtain new data on the structure of two-phase flow has been debugged on the example of a supersonic coaxial jet with a сentral fluid feeding at Npr=4 and Npr=6.
We used four main optical methods in the work:
1. Shadow visualization for check of geometry and wave structure of the jet;
2. PIV technique for the registration of the velocity field of the gas;
3. Laser Doppler anemometer (LDA) with a direct spectral analysis to measure the particles velocity of the spray;
4. The method of small-angle light scattering for the registration of dispersion of the spray implemented in the serial device Malvern “Spray Tech”.
The two last methods are of a local nature of the measurements and can detect the dispersion and velocity of droplets simultaneously at a single point of the flow. Simultaneous local measurements of velocity and size of droplets in a saturated gas-liquid flows performed for the first time. First proposed method for estimating the concentration of the liquid in the jet according to shadow imaging. It is shown that this configuration of optical methods of diagnostics allows to investigate complex high-speed gas-droplet jet in a wide range of gas velocities and liquid rate.

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