High-altitude ice crystal icing of aero engine is a serious threat to flight safety. Previous studies on ice crystal icing focused on the influence of air flow on ice crystals, but ice crystals also affect the engine flow field, which is often ignored in the research on the influence of ice crystals on engines. Numerical simulation based on Eulerian method is adopted to realize the two-way coupling between the compressor air flow and the particles in this study. The approach is demonstrated using the NASA compressor stage 35. The changes of compressor and particle parameters with different inlet total water content, relative humidity, and median volume diameter are calculated and analyzed, and the influence of ice crystal on the compressor performance is studied. The results show that the variation of relative humidity has a great influence on the particle temperature, median volume diameter, and wet bulb temperature. Median volume diameter has a great influence on the melt ratio. The variation of total water content has little effect on particle temperature, total water content, median volume diameter, and wet bulb temperature. The particle parameters are affected by the flow field of the compressor. The parameters show that the icing is easy to occur at the leading edge of NASA stage 35 stator. By contrast, the overall compressor characteristics, after ice particle injection, the total pressure ratio, and isentropic efficiency of the compressor are increased without considering ice crystal accretion, and the chocking boundary and stall boundary are not affected.
The turbulent flow between shrouded contra-rotating disks was numerically studied with a two-layer turbulence model and a modified Launder-Sharma low-Reynolds number k-e model. The dissipation rate decrease caused by solid body rotation was considered in the second model. The comparisons of the effectiveness between these two turbulence models for capturing the critical radius of flow structure transition and reproducing the flow velocity measurements data were presented. For the flow between shrouded disks rotating at the same speed but in opposite senses, that is, the angular velocity ratio of the two disks equals to 21, the Stewartson-type flow structure is found in the cavity. For the flow with one disk rotating more slowly than the other, Stewartson-type flow coexists with Batchelor-type flow, that is, Batchelor-type flow occurs radially outward of the stagnation point where two opposing boundary layer flows meet, and Stewartson-type flow occurs radially inward. The stagnation points near the slower disk move radially outward as the angular velocity ratio decreases toward 21. Theory of rotating fluids with the presence of centrifugal and Coriolis forces stemming from the disk rotation is employed to manifest the flow structure transition mechanisms as the rotation ratio of the disks is varied. The source of the earlier transition to turbulent flow in counter-rotating disk cavity compared with rotor-stator disk cavity is also explained through the research of instability of the flowing free shear layer formed by the counter secondary circulations. With the aid of the numerical results obtained from the two turbulence models, it is found that a more turbulent flow in the core can destroy the Batchelor-type flow and creates a larger Stewartson-type flow region.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.