Abstract

The simulation of the propagation of ultrasonic waves in a moving fluid will improve the efficiency of the ultrasonic flow monitoring and that of the in-service monitoring for various reactors in several industries. The most recent simulations are mostly limited to 3D representations of the insonified volume but without really considering the temporal aspect of the flow. The advent of high-performance computing (HPC) now makes it possible to propose the first 4D simulations, with the representation of the inspected medium evolving over time. This work is based on a highly accurate double simulation. A first computational fluid dynamics (CFD) simulation, performed in previous work, described the fluid medium resulting from the mixing of hot jets in a cold opaque fluid. There have been many sensor developments over the years in this domain, as ultrasounds are the only method able to give information in an opaque medium. The correct design of these sensors, as well as the precise and confident analysis of their measurements, will progress with the development of the modeling of wave propagation in such a medium. An important parameter to consider is the flow temperature description, as a temperature gradient in the medium deflects the wave path and may sometimes cause its division. We develop a 4D wave propagation simulation in a very realistic, temporally fluctuating medium. A high-performance simulation is proposed in this work to include an ultrasonic source within the medium and to calculate the wave propagation between a transmitter and a receiver. The analysis of the wave variations shows that this through-transmission setup can track the jet mixing time variations. The steps needed to achieve these results are described using the spectral-element-based numerical tool SPECFEM3D. It is shown that the low-frequency fluctuation of the liquid metal flow can be observed using ultrasonic measurements.

Highlights

  • Flow monitoring is of importance for many applications involving various liquids and gases

  • We designed an extensive physical and numerical simulation strategy to study the potential of ultrasonic measurements to monitor turbulent flow

  • The study was focused on liquid metal flows for which ultrasonic measurements are the best candidate to monitor flows

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Summary

Introduction

Flow monitoring is of importance for many applications involving various liquids and gases. Temperature heterogeneity could be described using stochastic methods, which randomly generate a fluctuating temperature field using a Gaussian random process This method has the great advantage of proposing a simplified model and of not requiring huge computer resources, but it does not model the real flow well [23]. We selected the PLAJEST setup, with the mixing of two hot jets with a cold one in a liquid metal medium [25] This setup was completely simulated using computational fluid dynamics tools [26,27]. The study is focused on the measurement of the frequency of these fluctuations, as it would prove the potential of such complete modeling for giving a 3D description of a heterogeneous flow and for monitoring it in time, thereby adding a fourth dimension to the simulation

Numerical Models for Wave Equation
Fluid Dynamics Modeling in PLAJEST Experiment and Frozen-Flow Hypothesis
Implementation of Wave Propagation Modelling
Temporal Temperature Fluctuation Measurement by Ultrasounds
Conclusions
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