Abstract: A fan assembly for a gas turbine engine includes a fan including a plurality of fan blades. Each fan blade extends radially outwardly from a fan hub to a blade tip. The plurality of blade tips define a fan diameter. A nacelle surrounds the fan and defines a fan inlet upstream of the fan, relative to an airflow direction into the fan. The nacelle has a forwardmost edge defining an inlet length from the forwardmost edge to a leading edge of a fan blade of the plurality of fan blades. A ratio of inlet length to fan diameter is between 0.20 and 0.45. A nacelle inner surface defines a nacelle flowpath. The nacelle flowpath has a convex throat portion and a concave diffusion portion between the throat portion and the leading edge of the fan blade at a bottommost portion of the nacelle.

Abstract: A fan assembly for a gas turbine engine includes a fan including a plurality of fan blades extending radially outwardly from a fan hub to a blade tip defining a fan diameter. A nacelle surrounds the fan and defines a fan inlet upstream of the fan, relative to an airflow direction into the fan. The nacelle has a forwardmost edge defining an inlet length from the forwardmost edge to a leading edge of a fan blade. A ratio of inlet length to fan diameter is between 0.20 and 0.45. A nacelle inner surface defines a nacelle flowpath having a convex throat portion and a diffusion portion between the throat portion and the leading edge of the fan blade at a topmost portion of the nacelle. The throat portion has a minimum throat radius measured from a fan central axis greater than a blade tip radius.

Abstract: A gas turbine engine comprises a nacelle and a fan rotor carrying a plurality of fan blades. The nacelle is formed with droop such that one portion extends axially further from the fan blades than does another portion. The nacelle has inner periphery that is substantially axially symmetric about a center axis of the rotor from either a throat of the nacelle at a substantially bottom dead center location, or a point of inflection at which the inner periphery of the nacelle at substantially bottom dead center merges a convex portion into a concave portion.

Abstract: A gas turbine engine assembly according to an example of the present disclosure includes, among other things, a fan including a plurality of fan blades, a diameter of the fan having a dimension D that is based on a dimension of the fan blades, each fan blade having a leading edge, a geared architecture configured to drive the fan, a turbine section configured to drive the geared architecture, a compressor section including a first compressor and a second compressor, and an inlet portion forward of the fan. A length of the inlet portion has a dimension L between a location of the leading edge of at least some of the fan blades and a forward edge on the inlet portion. A dimensional relationship of L/D is between about 0.2 and about 0.45.

Abstract: A gas turbine engine that includes a fan nacelle and a core nacelle that provide a bypass flow path radially between. The fan nacelle has an inlet including a throat. The inlet has an inlet forward-most point. A fan is arranged in the bypass flow path and rotatable about an axis. The fan has a leading edge recessed from the inlet forward-most point an inlet length in an axial direction. A spinner has a spinner length from a spinner forward-most point to the leading edge. A ratio of the spinner length to inlet length is equal to or greater than about 0.5.

Abstract: According to an example embodiment, a gas turbine engine assembly includes, among other things, a fan that has a plurality of fan blades. A diameter of the fan has a dimension D that is based on a dimension of the fan blades. Each fan blade has a leading edge. An inlet portion is situated forward of the fan. A length of the inlet portion has a dimension L between a location of the leading edge of at least some of the fan blades and a forward edge on the inlet portion. A dimensional relationship of L/D is between about 0.2 and about 0.45.

Abstract: A liner assembly for an aircraft engine housing includes a noise attenuation structure that is covered by a face sheet. The face sheet covering the noise attenuation structure includes a surface having a plurality of circumferentially spaced apart acoustic energy absorption areas that are interspersed between a corresponding plurality of acoustic energy reflective areas. The acoustic energy reflective areas scatter higher order acoustic modes into a plurality of lower order modes. The difficult to attenuate lower order acoustic modes produced by the various acoustic energy cancel each other out to provide significant improvement in liner noise reduction efficiency.

Abstract: A method for determining transmit power spectral density (PSD), includes: calculating time sharing parameters corresponding to transmission patterns for all users in each frequency band; and determining transmit PSD according to the transmission patterns and the time sharing parameters. A device for determining a transmit PSD including a calculation module and a PSD determining module is disclosed as well. Using the solution, the time for determining the transmit PSD can be saved.

Abstract: A liner assembly for an aircraft engine housing includes a noise attenuation structure that is covered by a face sheet. The face sheet covering the noise attenuation structure includes a surface having a plurality of circumferentially spaced apart acoustic energy absorption areas that are interspersed between a corresponding plurality of acoustic energy reflective areas. The acoustic energy reflective areas scatter higher order acoustic modes into a plurality of lower order modes. The difficult to attenuate lower order acoustic modes produced by the various acoustic energy cancel each other out to provide significant improvement in liner noise reduction efficiency.

Abstract: The film thickness and surface profile of a test sample consisting of optically dissimilar regions are measured by phase-shifting interferometry. Conventional phase-shifting interferometry at a given wavelength is performed to measure the step height between two regions of the surface. The theoretical measured step height as a function of the film thickness is then calculated. A set of possible solutions corresponding to the experimentally measured-height are found numerically or graphically by searching the theoretically generated function at the measured height. If more than one solution exists, the phase-shifting procedure is repeated at a different wavelength and a new theoretical measured-height as a function of the film thickness is calculated for the optical parameters of the materials at the new wavelength, yielding another set of possible solutions that correspond to the newly measured height. The number of repetitions of the procedure depends on the number of unknowns of the test sample.