Abstract: A nacelle defining an intake is provided for channelling and conditioning freestream airflow to a fan of a ducted fan gas turbine engine. The nacelle intake comprises in flow series an intake lip, and a diffuser. The intake lip has at its forwardmost end a highlight which is a closed loop defining a boundary between inner and outer surfaces of the nacelle, and the diffuser terminates at its rearwardmost end at a front face of the fan. The intake has a circumferentially extending shock control bump or a series of circumferentially spaced shock control bumps formed thereon.

Abstract: A nacelle for a turbofan gas turbine engine, having in flow series an intake lip, a diffuser and a fan casing. The diffuser has, in flow series, a main section and a recessed section adjacent to the fan casing. A transition region, such as a step, slope or curve, is provided between the main section and the recessed section. In some arrangements the transition region may be configured to promote flow separation and the formation of a separation bubble in the recessed section.

Abstract: A nacelle for a turbofan gas turbine engine, having in flow series an intake lip, a diffuser and a fan casing. The diffuser has, in flow series, a main section and a recessed section adjacent to the fan casing. A transition region, such as a step, slope or curve, is provided between the main section and the recessed section. In some arrangements the transition region may be configured to promote flow separation and the formation of a separation bubble in the recessed section.