Experimental study on transient self-priming process of rotary lobe pump

The objective of this study is to examine the variations in self-priming performance and external characteristic parameters of a rotor pump during the start-up and self-priming transition phases. To this end, a self-priming performance test apparatus, appropriate for high suction range pumps, was developed. By monitoring the fluctuations in inlet vacuum levels and external characteristic parameters throughout the self-priming process, experiments were conducted under five distinct conditions: inlet vacuum levels of 0.07 MPa, and rotational speeds of 200 rpm, 250 rpm, 300 rpm, 350 rpm, and 400 rpm. The results obtained offer insights into the alterations in external characteristic parameters during the self-priming process. Based on the phase state of the suction medium, the self-priming process can be categorized into three stages: the inspiratory stage, the gas-liquid mixed transport stage, and the normal operation stage. The experimental findings indicate that the operating speed significantly influences the self-priming process, primarily reflected in the changes in external parameters. The response of shaft power to the inlet vacuum degree is more pronounced at higher speeds. From the perspective of flow rate variation, the rate of flow change is faster at higher speeds, and the conveying efficiency is higher during the gas-liquid mixed transport stage. Analyzing the self-priming performance reveals that speed has a greater impact on the inspiratory stage of the self-priming process and a lesser impact on the gas-liquid mixed transport stage. The differences in the duration of the self-priming process at various speeds are mainly attributed to the duration of the inspiratory stage.