Effects of pump parameters on the oil absorption characteristics of bidirectional involute internal gear pumps

Abstract

The symmetrical oil suction and discharge chambers and the reversing rotation condition of bidirectional involute internal gear pumps result in low oil absorption capacity and flow pulsation due to cavitation. However, efforts to address these issues suffer from an incomplete understanding of the effects of oil properties, suction chamber volume, suction pressure, and rotational speed on the oil absorption capacity and cavitation characteristics of these pumps. The present work addresses this issue by conducting detailed computational fluid dynamics (CFD) simulations. The results of analysis demonstrate that the degree of cavitation caused by changes in the mass fraction of dissolved gas in the oil is positively correlated with flow pulsation, while the degree of cavitation caused by changes in the suction port size, suction pressure, and rotational speed is negatively correlated with flow pulsation. The degree of cavitation in the oil suction cavity initially increases as the mass fraction of dissolved gas in the oil increases, and then decreases. The rotational speed exhibits a critical value, where the oil absorption capacity increases with increasing rotational speed below the critical value, and decreases with increasing rotational speed above the critical value. The results of this research are expected to be of great significance for guiding improvements in the design of bidirectional involute internal gear pumps and the determination of critical working conditions.