To study the influence of orifice spacing on the oil–air two-phase flow and the oil capture efficiency of an oil scoop in an under-race lubrication system, an experimental platform for under-race lubrication was built, and a calculation model for the oil–air two-phase flow field was established. The rationality of the experiment and the validity of the numerical model were verified by comparing the experimental and numerical results. The results showed that under the same oil supply pressure, the captured oil mass flow rate of the double-orifice structure was much higher than that of the single-orifice structure, though it was still less than twice that of the single-orifice structure. When applying a tandem layout structure of double orifices to an under-race lubrication system, the orifice spacing of the tandem layout structure should be determined based on a full evaluation of the influence of the orifice spacing and working condition parameters on the oil capture performance. Otherwise, it may lead to a decrease in oil capture efficiency, with the maximum reduction even reaching 12%.

Hail absorption test of aeroengine is one of the important components of airworthiness certification. The accurate test data are closely related to the density and mechanical properties of the artificial hail used in airworthiness tests. Through experimental research, this study explores the impact of distilled water, carbonated water and deionized water on the density and mechanical properties of artificial hail. The study addresses the significant differences between the density and mechanical properties of artificial hail and natural hail in existing studies. Based on this, a new method for preparing airworthiness test hail is proposed. The results indicate that artificial hail samples with distilled water as the hail core and carbonated water as the hail shell have densities ranging from 0.87 cm³ to 0.89 cm³. Furthermore, the estimated average maximum compressive strength of samples is 6.538 MPa, with some samples as low as 3.681 MPa. The mechanical properties of this artificial hail are more similar to those of natural hail. This method can more realistically simulate natural hail environments and can be used for the fine design of airworthiness certification criteria.