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1. How to calculate the β value of a V-shaped cone flowmeter?
After simplification, the formula is: QV - fluid volume flow rate m3/hCd - outflow coefficient β V - equivalent straight to turbulent diameter ratio dV - wadou is the maximum diameter of the cone, D is the inner diameter of the pipeline ρ - density under fluid conditions ε - mu side - gas expansion coefficient.
2. Calculation principle of V-shaped installation of ultrasonic flowmeter.
The core calculation principle of V-shaped installation of ultrasonic flowmeter is to calculate the flow rate and flow rate by measuring the time difference of ultrasonic propagation in both directions. 1. Basic principle architecture: In the V-shaped installation mode, two transducers are installed symmetrically on the same side of the pipeline in a mirror image, forming an ultrasonic path with an angle of about 60 degrees. This layout completes signal transmission through two fluid refractions, making it more suitable for small pipe diameter scenarios compared to Z-type installations. When ultrasonic waves propagate downstream, the actual transmission speed is the sum of the sound velocity c and the fluid flow velocity v. The corresponding time calculation formula is: t ₁=L/(c+v · cos θ), where θ is the angle between the ultrasonic path and the fluid axis. When propagating in reverse, there is a decrease in velocity, corresponding to a propagation time of t ₂=L/(c-v · cos θ). By calculating the time difference, △ t=t ₂ - t ₁ is derived as v=(L ·△ t)/(2t ₁ t ₂ · cos θ). In engineering applications, the sound velocity compensation algorithm is usually introduced to correct the value of c by real-time detection of the temperature and pressure parameters of
3. After obtaining the average flow velocity v in the flow conversion stage, combined with the pipe cross-sectional area A (A=π D ²/4), the volume flow rate Q=K · vA is obtained through integration calculation. Here K is the flow correction coefficient, which needs to be dynamically calibrated based on parameters such as Reynolds number and flow velocity distribution. 4. Error compensation mechanism. The V-shaped installation has a unique secondary refraction effect that introduces signal attenuation, and an energy attenuation model corresponding to the delay basis needs to be established. In practice, a combination measurement method of time difference method and cross-correlation algorithm is usually used to increase the time resolution to the order of 0.1ns, making the lower limit of flow velocity detection reach 0.01m/s. The measurement accuracy of this installation mode can usually reach ± 1% R (1% of full scale), which basically covers the conventional industrial pipe diameter requirements of DN50-DN300 under the condition of meeting the requirement of pipeline straight pipe length ≥ 15D.
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