Oil removal from aeroengine bearing chambers presents an on-going challenge for aeroengine designers. Effective scavenging of oil is necessary to avoid excessive heat in the bearing chamber as this may lead to degradation of the oil and deterioration in heat transfer functionality. However the task of oil removal is not trivial. Oil is entrained in a highly rotating environment induced by rotating shafts. Simply "sucking harder" with a scavenge pump may lead to considerable air ingestion, reducing flow area for the oil to exit through and trapping oil in the sump (chamber exit zone) to be heated and mixed with the hot air. In a recent study a sump design incorporating curved walls and a deep offtake region was found to perform well. In the work reported here, shallow variants of this Curved Wall Deep Sump (CWDS) design are investigated. A design of experiments approach was applied. Five geometric parameters controlling the design were identified and these five factors at two levels were analysed using a half fraction factorial resolution Ⅴ design resulting in 16 possible configurations. Performance of the designs was assessed using numerical categorisation of visualisation data relating to extent of hydraulic uplift in the scavenge region. In addition to the geometric factors, the flow condition factors liquid flow rate, shaft speed, and scavenge ratio were also investigated. A statistical software (Minitab) was used to conduct Design of Experiments (DoE) analysis on the data. An ANOVA analysis was also conducted. The study found that the performance of all shallow variants of the CWDS was quite similar - no outstanding design was identified. Deeper, wider designs appeared to perform somewhat better than shallower, narrower ones. The rotated offtake designs appear to be somewhat better than the vertical offttakes. A clear finding is that there is improved performance where liquid is introduced as film rather than as droplets. For reduced hydraulic uplift designs that encourage film flow may perform better.
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