Speed of Sound
For the determination of speed of sound (sonic speed, acoustic velocity) for liquids an apparatus is available in our laboratory for pressures up to 200 bar and temperatures from 273 to 393 K.
- Ultrasonic cell for liquid speed of sound (ThermoVersum Project, up to 200 bar, 273 to 393 K
Ultrasonic Cell for Liquid Speed of Sound Measurements
The speed of sound data for liquids can be measured with an automated setup. A speed of sound chamber with two piezoelectric transducers as transmitter and receiver mounted at opposing walls is the core of the apparatus. The method for the speed of sound determination operates in the through-transmission mode and measures the propagation time of short acoustic pulses which are repeatedly transmitted through the liquid sample. Using a tunable voltage controlled oscillator this technique was invented by Heimel, Leopold and Stabinger and is employed for the commercial speed of sound measurement apparatus DSA 5000 from Anton Paar (Graz, Austria).
The pressure cell (see following figure) is a prototype from the Labor fuer Messtechnik Stabinger (Graz, Austria). It is applicable for speed of sound measurements of liquids between about 700 and 2000 m/s at temperatures between 273 and 393 K and pressures up to 20 MPa. Using a liquid circulation cryostat/thermostat or an electric heating the cell can be thermostatted. The temperature is monitored with a Pt100 resistance probe mounted directly in the pressure cell. For the high pressure measurements the pressure cell is connected to an electronic controlled piston pump. The pressure is monitored by a calibrated pressure transducer.