Abstract: Fluid flowmeter, air conditioning system and method of controlling the air conditioning system which includes a Karman vortex generator, ultrasonic transmitter and receiver apparatus and networks for detecting the Karman vortices and for detecting and controlling information of a received wave and a reference wave of the ultrasonic transmitter. The flowmeter detects an air flow volume and/or speed by Karman vortex detecting means using ultrasonic waves. The air conditioning system utilizes the fluid flowmeter for measuring air flow volume and/or flow speed in a duct between an air conditioning apparatus and a chamber to control air flow volume in response to information from the flowmeter.

Abstract: Fluid flowmeter which includes a Karman vortex generator, ultrasonic transmitter and receiver apparatus and networks for detecting the Karman vortices and for detecting and controlling information of a received wave and a reference wave of the ultrasonic transmitter. The flowmeter detects an air flow volume and/or speed by Karman vortex detecting means using ultrasonic waves.