Enter the diameter of the thermowell tip, flow velocity, Strouhal number, and the diameter of the thermowell shank into the calculator to determine the wake frequency.

Wake Frequency Formula

The following formula is used to calculate the wake frequency in a thermowell.

WF = (D * V * St) / d

Variables:

  • WF is the wake frequency (Hz) D is the diameter of the thermowell tip (m) V is the flow velocity (m/s) St is the Strouhal number (dimensionless) d is the diameter of the thermowell shank (m)

To calculate the wake frequency, multiply the diameter of the thermowell tip by the flow velocity, then multiply the result by the Strouhal number. Divide the first result by the diameter of the thermowell shank.

What is a Wake Frequency?

Wake frequency is a term used in fluid dynamics and process engineering, referring to the frequency of oscillations caused by a flow disturbance such as an object moving through a fluid or gas. It is particularly important in the design of probes and sensors used in fluid flow measurement, as it can affect the accuracy of measurements. The wake frequency must be less than the natural frequency of the system to avoid resonance and potential damage.

How to Calculate Wake Frequency?

The following steps outline how to calculate the Wake Frequency using the given formula:


  1. First, determine the diameter of the thermowell tip (D) in meters.
  2. Next, determine the flow velocity (V) in meters per second.
  3. Next, determine the Strouhal number (St) which is dimensionless.
  4. Next, determine the diameter of the thermowell shank (d) in meters.
  5. Finally, use the formula WF = (D * V * St) / d to calculate the Wake Frequency.

Example Problem:

Use the following variables as an example problem to test your knowledge:

Diameter of the thermowell tip (D) = 0.05 m

Flow velocity (V) = 2 m/s

Strouhal number (St) = 0.2

Diameter of the thermowell shank (d) = 0.02 m