Determination of the fluid forces on a baffled mixing vessel impeller
University of New Brunswick
A novel linear model of vibration for industrial mixing equipment is introduced. The model includes contributions to the mass, damping and stiffness coefficients from fluid forces on the impeller, in addition to structural elements. The fluid added mass, damping and stiffness model coefficients were derived from Large Eddy Simulation (LES) of a mixer with a pitched blade impeller undergoing small prescribed circular orbits. Simulations were performed at Reynolds numbers of 10, 10, 1000 and 10,000 and with whirl frequency ratios of 0/21rN = ±0.5, ±1.0 for each Reynolds number. Model predictions of impeller whirl instability and mean square vibration amplitude were compared to experimental data from a laboratory scale mixer with good agreement.