Thermowell Wake Frequency Calculation May 2026

[ f_n = \frac\lambda^22\pi L^2 \sqrt\fracEIm ]

[ St = \fracf_w \cdot dV ]

(simplified uniform beam): ( I = \frac\pi (d_root^4 - d_bore^4)64 ) (assume bore dia 6 mm → 0.006 m) ( I ≈ 8.9 × 10^-8 , m^4 ) ( m_metal = \rho_m × \textcross-sectional area ≈ 8000 × 7.85e-4 = 6.28 , kg/m ) ( m_added = 1000 × 4.91e-4 = 0.49 , kg/m ) ( m_total = 6.77 , kg/m ) thermowell wake frequency calculation

determines the vortex shedding frequency and compares it to the thermowell’s natural frequency to ensure safe operation. 2. Governing Physics 2.1 Strouhal Number (St) The dimensionless Strouhal number relates vortex shedding frequency to flow velocity and thermowell diameter: [ f_n = \frac\lambda^22\pi L^2 \sqrt\fracEIm ] [

1. Introduction A thermowell is a pressure-tight receptacle inserted into a process pipe or vessel to protect a temperature sensor (e.g., RTD, thermocouple) from corrosive, high-pressure, or high-velocity fluids. When fluid flows past a thermowell, alternating vortices shed from its downstream side—a phenomenon known as vortex shedding or a Kármán vortex street . This can cause large-amplitude vibrations

If the frequency of these vortices coincides with the natural frequency of the thermowell, occurs. This can cause large-amplitude vibrations, leading to fatigue failure, fracture, and loss of process containment.