Ultrasonic multi-channel flow measuring method

An ultrasonic multi-channel flow rate measuring method for measuring a flow rate of a fluid in a fluid section of a pipe, the method comprising:

• measuring by using at least one ultrasonic wave, a flow rate QI of a section SI representing a circular section having a radius R of the fluid section, the radius R being less than a standard radius Rs of the pipe;
• calculating by using a flow velocity distribution curve, a flow rate QII of a section SII representing a remaining section of the fluid section not measured by the ultrasonic wave, the flow velocity distribution curve including a relationship between a ratio VII/VI and a ratio ΔR/Rs, wherein VII represents a measured flow velocity of the section SII, VI represents a flow velocity of the section SI, and ΔR represents a sum of:
• (i) a maximum deviation of the standard radius RS;
• (ii) a thickness of a corrosive resistance layer in the pipe;
• and (iii) a deviation of the thickness of the corrosive resistance layer;
• and
• determining a total flow rate Q of the fluid section based on a sum of the flow rate QI and the flow rate QII.