An installed heat exchanger exhibited severe vibrations, that threatened its structural integrity and operating efficiency. It was initially assumed that the flow presented unsteadiness, that carried high kinetic energy and induced vibrations. To examine this, the timeseries of the fluid’s force on the walls was analyzed, to detect the frequencies of considerable energy flows.

The needed timeseries were acquired, by developing a transient CFD model for the flow inside the exchanger. The time-step was small enough to cover the targeted high frequencies. The heat exchanger had two circuits, one for the gas and the other for the liquid water phase. Since, the two circuits exchange only heat with each other, they were solved by two separate CFD models. The timeseries of the force applied to the walls were analyzed for the regions with high perturbation and recirculations. No indication was found of a loading with both significant magnitude and distinct frequency value, so the company engineers were able to search for other probable cause.