Abstract The relatively low entrainment ratio is the key problem that confines the ejector development in the industry. In this study, the adjustable-geometry ejectors (with three different spindle positions) and ejectors with bypass (with two different bypass inlet installations) were adopted to promote the entrainment ratio of an ejector. The performance of the adjustable-geometry combined with bypass was also investigated. Results showed that the adjustable-geometry ejector and ejector with bypass could improve the entrainment ratio, and both ejectors reached a peak value. Compared with the original ejector, the maximum increment was 51.47% for the adjustable-geometry ejector and 26.0% for the ejector with bypass, respectively. Meanwhile, the combined ejector increased the entrainment ratio, although the combination was only effective at higher induced pressures than that of the adjustable-geometry ejector without bypass. The maximum increment was up to 74.5% compared to that of the original ejector.