Advanced Ducted Engine Nacelle Aerodynamics and Integration Testing

McCall, Jack; Tracksdorf, Peter; Heinig, Klaus

doi:10.1115/1.2906660

Cited by 3 publications

(1 citation statement)

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“…In independent experimental studies, McCall et al [41] and Ingraldi et al [42] reported that interference drag penalties in high-bypass ratio nacelle installations were approximately the same as for conventional-type nacelles (BP R = 18 vs. BP R = 6 in the latter study). Instead, wave drag due to shock waves forming on the nacelle surface was identified a challenge in short nacelles [40].…”

Section: Previous Work On Low-fpr Propulsor Performancementioning

confidence: 99%

Ultra-Short Nacelles for Low Fan Pressure Ratio Propulsors

Peters¹,

Spakovszky²,

Lord³

et al. 2014

Volume 1A: Aircraft Engine; Fans and Blowers

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This thesis addresses the uncharted inlet and nacelle design space for low pressure ratio fans for advanced aeroengines. A key feature in low fan pressure ratio (FPR) propulsors with short inlets and nacelles is the increased coupling between fan and inlet. The thesis presents an integrated fan-nacelle design framework, combining a spline-based tool for the definition of inlet and nacelle surfaces with a fast and reliable body-force-based approach for the fan rotor and stator blade rows. The new capability captures the inlet-fan and fan-exhaust interactions and the flow distortion at the fan face and enables the parametric exploration of the short-inlet design territory. The interaction of the rotor with a region of high streamwise Mach number at the fan face is identified as the key aerodynamic mechanism limiting the design of short inlets. The local increase in streamwise Mach number is due to flow acceleration along the inlet internal surface coupled with a reduction in effective flow area. For a candidate short-inlet design with inlet length to fan diameter ratio L/D = 0.19, the streamwise Mach number at the fan face near the shroud increases by up to 0.16 at cruise and by up to 0.36 at off-design conditions relative to a long-inlet baseline propulsor with L/D = 0.5. As a consequence, the rotor locally operates close to choke, resulting in fan efficiency penalties of up to 1.6 % at cruise and 3.9 % at off-design. For inlets with L/D < 0.25, the benefit from reduced nacelle drag is offset by the reduction in fan efficiency, resulting in propulsive efficiency penalties. Based on a parametric inlet study, the recommended inlet L/D for engine propulsive efficiency benefits is suggested to be between 0.25 and 0.4. A candidate design with L/D = 0.25 maintains the cruise propulsive efficiency of the baseline case without jeopardizing fan and LPC stability at off-design conditions. On the aircraft system level, fuel burn benefits are conjectured to be feasible due to the reductions in nacelle weight and drag compared to an aircraft powered by the long-inlet baseline propulsor.

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Section: Previous Work On Low-fpr Propulsor Performancementioning

confidence: 99%