Magnetohydrodynamic instability in annular linear induction pump

Development of a three-dimensional magnetohydrodynamics code for electromagnetic pumps

“…During the passage of time, reversed flow of the sodium was observed and strong vortices developed toward the end of the pump. These types of vortices would be the same phenomena observed by Araseki et al [5] under a condition that Rm × s was greater than unity.…”

“…Low-frequency (LF) pressure pulsation is considered as one of the magnetohydrodynamic instabilities. This was reported by Araseki et al [5] and other researchers [3,4]. According to [5], this instability is initiated by circumferential non-uniformity in the sodium flow velocity and/or of the magnetic fields and ends up with vortices in the sodium flow.…”

“…Reducing the flow rate and setting the operation point near the peak of the P-Q curve sometimes bring about developed pressure drops and fluctuations [1]. These fluctuations were reported as instability by Gailitis et al [3], Kirillov et al [4], and Araseki et al [5]. The instability was characterized by vortices, which were initiated by circumferential non-uniformity of sodium velocity and/or magnetic field, in the sodium flow.…”

Instability in electromagnetically driven flows. I

“…First, it has been shown through numerical and experimental studies [7] that even at low Rm, the efficiency of such pumps is affected by an amplification of the electromagnetic forcing, which takes the form of a strong pulsation at double supply frequency (DSF). Second, it has been confirmed that at large Rm, an azimuthal non-uniformity of the applied magnetic field or of the sodium inlet velocity can create vortices in the annular gap [8]. In both cases (large and low Rm), some solutions have been proposed to inhibit the occurrence of these perturbations, but this generally leads to a strong loss of efficiency of the pump.…”

“…According to this model, the instability occurs above some critical magnetic Reynolds number Rm c and takes the form of an inhomogeneity in the azimuthal direction. Several experimental studies [6,8] have shown that when Rm > Rm c , a low frequency pulsation in the pressure and the flow rate is indeed observed, strongly reducing the efficiency of the pump. More recently, significant progress has been done on the understanding of these electromagnetically driven flows.…”