Institute of Mechanics Laboratory of Experimental Hydrodynamics
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Aerodynamic facilities

Aerodynamic complex of the laboratory of experimental hydrodynamics consists of several facilities for the investigations of free jets, coaxial jets, flows in various channels and tubes. An air with the pressure of 6 atm. is lined to the complex, which is fitted with the measuring and processing equipment, particle image velocimetry (PIV) system, software in LabView environment.
  • The setup for the formation of laminar jets is designed for the study of free jets and flows in the forming devices, which provides desired velocity profile and low intensity of turbulent fluctuations at its outlet.

      
    Experimental setup for investigations of flows in short diffusers.


    Air laminar jet visualized by light-reflecting glycerin particles and laser sheet.


    Investigation of disturbance growth in laminar jet by PIV method.


  • The setup forming coaxial jets is used to demonstrate the influence of the initial conditions (velocity and turbulent fluctuations profiles) on the mixing layer length of circular and annular gas jets at high Reynolds numbers. The setup is based on the method, which uses honeycombs for creating velocity profiles with low turbulent intensity at its outlet.

    Visualization of non-mixing laminar circular and annular jets.


  • The setup for investigating the flows in channels of small angle of expansion is used to study near-critical turbulent flows. New experimental and numerical results are obtained. It is shown that the transition to the turbulence in conical channel with expansion angle less than 1° occurs at the Reynolds number of the half of the value of the critical Reynolds number in circular tube.

      
    Experimental setup for investigations of flows in long diffusers.


Main measuring equipment includes flowmeters, manometers, Honeywell absolute and differential pressure transducers, DISA 56C01 CTA and DISA  55M12 thermoanemometers.

Thermoanemometer probe measuring average velocity and turbulent fluctuation profiles near the diffuser outlet.


In 2016, aerodynamic facilities have been fitted with Polis particle image velocimetry system. The system is based on the methods of digital tracer visualization for the measuring velocity fields in flows.

PIV is an optical method of instantaneous velocity fields measuring in fluids. Impulse laser creates thin light sheet and illuminates airborne small light-reflecting particles. Particles locations at the moments of two consecutive laser flashes are registered in two frames of high-speed camera. The flow velocity is calculated by the displacement of the particles in the time interval between two laser flashes. Displacement calculation is based on the application of correlation methods to the tracer images, using regular partition of the testing section to elementary regions.

Impulse laser and high-speed camera.


PIV system components:
  • illumination system based on the impulse Nd:YaG laser with the objective for the laser sheet,
  • registration system based on the Bonito CL-400B camera and a lens,
  • ActualFlow software,
  • personal computer,
  • aerosol generator.
PIV system measures up to 100 instantaneous velocity vector fields per second, which enables to investigate high-speed unsteady processes in fluid flows.
Last update: august of 2024