Noninvasive acoustical property measurement of fluids

A method for noninvasively measuring acoustical properties of a fluid, said method comprising the steps of:

• applying a shaped pulse signal to a first ultrasonic transducer in vibrational communication with an outside surface of a pipe having a wall and through which said fluid is flowing, the shaped pulse signal being a Gaussian modulated sine pulse, whereby vibrations are generated in said fluid and in the pipe wall;
• detecting the generated vibrations on a second ultrasonic transducer disposed on the outside surface of the pipe diametrically opposite to the first ultrasonic transducer with fluid flowing through the pipe, whereby a first time-dependent electrical signal is obtained;
• introducing a chosen gas into the fluid to a gas volume fraction such that no vibrations pass through the fluid;
• applying the shaped pulse signal to the first ultrasonic transducer, whereby vibrations are generated solely in the pipe wall;
• detecting the generated vibrations on the second ultrasonic transducer with no vibrations passing through the fluid, wherein a second time-dependent electrical signal is obtained;
• subtracting the second electrical signal from the first electrical signal whereby a difference electrical signal is generated;
• determining a time-of-flight of the vibrations between the first transducer and the second transducer using the difference electrical signal;
• and
• determining acoustical properties of the fluid using the determined time-of-flight of the vibrations.