Scientific Activity

Laboratory of Flow Metrology

Flow metrology – thermoanemometry

Key achievements of the Laboratory are the following:

  • Thermal wawes anemometry
    On the basis thermal waves theory developing a method for absolute measurement of gas flow velocity, applied in calibrating wind tunnels for speed values across the 5 cm/s – 5 m/s range.
  • Developing method of temperature compensation of thermoanemometers readings
    The method involves using a single-wire sensor working with the overheating ratio, periodically changing over time. The output signal of the thermoanemometer is used to determine flow velocity and the temperature of the medium. The method is applied in studying velocity and temperature fields in non-isothermal flows.
  • Innovative bridgeless constant temperature anemometer
    Thermoanemometric sensor is connected in a four-point manner to electronic system, which makes it possible to eliminate the effect of the probe wire resistance on the accuracy of the measurement. The system displays excellent static and dynamic parameters, and is successfully applied in precision thermoanemometric measurements.
  • Digital constant temperature thermoanemometer system
    In this system the overheating ratio is managed by a digital signal. This controlled constant temperature system is applied in PC-based complex measuring systems.
  • Novelty bridge constant temperature system with temperature compensation.
    This system allowing the application of a compensation sensor of any resistance. The modification involves transformating voltage in the compensatory branch of the bridge, and reduces measurement errors issuing from the temperature gradient in the medium being investigated.
  • Innovative solutions of thermoanemometric measuring equipment,
    This solution can be used for laboratory research purposes, in technological processes, and in industry. These include stationary and portable anemometers, analogue and microprocessor instruments, thermoanemometric computer cards, and complex measuring systems. All of them find their application in scientific studies, as well as in technical measurements carried out in numerous research centers at home and abroad.
  • Design thermoanemometric sensors
    There are hot-wire sensors, single- and multiwire sensors, to be used for research purposes and in laboratory measurements connected with studies into aerodynamics, thermodynamics, and heat and mass exchange, as well as in technical studies into ventilation and air conditioning, investigating technological processes and other issues. In this field, the Laboratory of Flow Metrology of the Strata Mechanics Research Institute is a leader on a country-wide scale.

Investigating gas-geodynamic phenomena in coal

Key achievements of the Laboratory are the following:

  • developing a method for measuring the kinetics of gas desorption, which takes into account the initial moment of the phenomenon in question – diffusion coefficients for various types of coal (outburst and non-outburst ones) were calculated;
  • formulating a hypothesis concerning the initiation of coal and gas outburst, with an assumption that coal saturated with gas in a retrograde medium;
  • on the basis of Classical Irreversible Thermodynamics, constitutive equations of coal saturated with gas were formulated;
  • the time constant of gas desorption from hard coal was investigated (it was established to be less than 5 ms);
  • several chambers for investigating the destruction mechanism of coal briquettes, saturated with various gases up to the pressure value of ca. 0.7 MPa, were built. The outburst initiates an abrupt decrease in the free gas pressure. Pictures taken with a high-speed camera prove that, during the outburst, successive layers of coal, thicker than 2 mm, are severed from the briquette. During the destruction process, changes of pressure in the briquette pores, as well as briquette temperature and deformation, are recorded. The research proves that, before a crack in the briquette appears, the briquette expands (its relative deformation exceeds 20 percent), its temperature drops by ca. 8 K, and the time derivative of pressure in successive measurement points increases.