As early as 1738, the Swiss scientist Daniel Bernoulli utilized the differential pressure method to measure water flow, based on what is now known as Bernoulli's principle. Later, the Italian G.B. Venturi investigated the use of Venturi tubes for flow measurement and published his findings in 1791.
In 1886, the American Clemens Herschel developed a practical device for measuring water flow based on the Venturi tube.
From the early to mid-20th century, existing measurement principles matured; researchers began to look beyond traditional methods and embarked on new avenues of exploration.
By the 1930s, methods for measuring liquid and gas flow velocities using sound waves had emerged, though little significant progress was made prior to World War II. It was not until 1955 that the Maxson flow meter-which employed the acoustic circulation method-was introduced for measuring aviation fuel flow.
From the 1960s onwards, flow measurement instruments began to evolve towards greater precision and miniaturization.
With the rapid advancement of integrated circuit technology, ultrasonic flow meters incorporating phase-locked loop (PLL) technology came into widespread use. Furthermore, the extensive application of microcomputers significantly enhanced flow measurement capabilities; for instance, the integration of microcomputers into laser Doppler velocimeters enabled the processing of complex signals.
