Non-contact and non-invasive water level measurement outside metal pipes with electromagnetic acoustic resonance

Accurate measurements of water levels within metal pipes are vital, particularly in environments where thick-walled pipes serve as critical components, such as in nuclear facilities. Measuring water levels in pipes becomes more difficult under high temperatures and pressures. In response to this need, a method involving electromagnetic acoustic measurement is proposed. This method begins with a transducer emitting a high-frequency pulse designed for precise measurements of wall thickness, then calculates the resonance frequency using the time intervals between echoes. Finally, the transducer emits an excitation signal at the fundamental resonance frequency to measure the water level. At low water levels, the measurement is conducted by manually scanning along the pipes, utilizing varying energy losses. At high water levels, the resonance echo method is employed. Numerical simulations have demonstrated that this approach effectively improves signal amplitude, thereby ensuring the robustness of the measurement. Experimental results also demonstrated that the proposed method boosted the echo signal-to-noise ratio to approximately 15 dB. Additionally, it successfully detected water levels in both aluminum and stainless-steel pipes. Therefore, it is considered to be a highly efficient non-contact and non-invasive method to measure liquid levels in metal pipes, and it has proved to hold significant potential for engineering applications.