Numerical investigation of design parameters for optimization of the in-situ ultrasonic fouling removal technique for pipelines

A Dual Frequency Ultrasonic Cleaning Tank Developed by Transient Dynamic Analysis

At present, development of manufacturer’s ultrasonic cleaning tank (UCT) to match the requirements from consumers usually relies on computer simulation based on harmonic response analysis (HRA). However, this technique can only be used with single-frequency UCT. For dual frequency, the manufacturer used information from empirical experiment alongside trial-and-error methods to develop prototypes, resulting in the UCT that may not be fully efficient. Thus, lack of such a proper calculational method to develop the dual frequency UCT was a problem that greatly impacted the manufacturers and consumers. To resolve this problem, we proposed a new model of simulation using transient dynamics analysis (TDA) which was successfully applied to develop the prototype of dual frequency UCT, 400 W, 18 L in capacity, eight horn transducers, 28 and 40 kHz frequencies for manufacturing. The TDA can indicate the acoustic pressure at all positions inside the UCT in transient states from the start to the states ready for proper cleaning. The calculation also reveals the correlation between the positions of acoustic pressure and the placement positions of transducers and frequencies. In comparison with the HRA at 28 kHz UCT, this TDA yielded the results more accurately than the HRA simulation, comparing to the experiments. Furthermore, the TDA can also be applied to the multifrequency UCTs as well. In this article, the step-by-step development of methodology was reported. Finally, this simulation can lead to the successful design of the high-performance dual frequencies UCT for the manufacturers.

Parametric Study of Bolt Clamping Effect on Resonance Characteristics of Langevin Transducers with Lumped Circuit Models

We recently proposed a numerical model using equivalent circuit models to analyze the resonance characteristics of Langevin transducers and design them in a systematic manner. However, no pre-load torque biased by a metal bolt was considered in the model. Here, a parametric study is, therefore, carried out to reveal how model parameters are adapted to incorporate the pre-compression effect into our existing model. Analytical results are compared with corresponding experimental data, particularly regarding the input electrical impedance and effective electromechanical coupling coefficient for the transducer at resonance modes. The frequency response of input impedance is presented as a function of torque, both theoretically and experimentally. For 10.0 N·m bias, for instance, both resonance and anti-resonance frequencies are calculated as 38.64 kHz and 39.78 kHz, while these are measured as 38.62 kHz and 39.77 kHz by the impedance analyzer. The impedance difference between these cases is 14 Ω at resonance and 9 kΩ at anti-resonance, while the coupling coefficients in both cases become 0.238 and 0.239, respectively. Hence, these test results are closely matched with their theoretical values. Consequently, this study provides a quantitative guideline that specifies the pre-loading condition of bolt clamps with proper parameter settings to predict the intended resonance characteristics of Langevin transducers.

Ultrasonic Transducer Array Performance for Improved Cleaning of Pipelines in Marine and Freshwater Applications

Fouling accumulation in pipelines is a well-known problem in industry across various applications. The build-up of fouling within a pipe can reach a detrimental state, leading to pipe blockages that, in turn, result in pipe bursts. As pipelines transport fluid up to hundreds of meters, a method to prevent and remove fouling at long distances is required to support an engineering structure without the requirement of halts for maintenance to be carried out. Underwater pipelines are currently deployed which must ensure that pipelines carrying crude oil do not reach a detrimental state which leads to pipe leaks or pipe bursts, resulting in a discharge of oil into the surrounding water. This work discusses an optimized ultrasonic cleaning transducer array which undergoes marinization. The marinized transducers are characterized for impedance and wave propagation across a fouled 6.2 m long, Schedule 40, 6-inch diameter carbon steel pipe. This study has shown that the addition of marinized material dampens the vibrational output from the High-Power Ultrasonic Transducer (HPUT) configuration. This reduction in vibration is most significant when the structure is filled with water, resulting in a marinized HPUT configuration dropping by up to 85% and a non-marinized HPUT configuration dropping by up to 80%.