Engineering topics

Gedge, M. R.

Publications and source records attributed to Gedge, M. R..

3 records

NASA NTRS1980

A design procedure for fan inflow control structures

Significant differences exist in the noise generated by engine in flight and engines operating on the test stand. It was observed that these differences can be reduced by use of an inflow control structure (ICS) in the static test configuration. The results of the second phase of a three phase program are described and the results of a test program conducted to assess and modify various theoretical models, leading to the development of an ICS design system is summarized.

Gedge, M. R.↗

NASA NTRS1980

Studies on proper simulation during static testing of forward speed effects on fan noise

Significant differences exist in the noise generated by engines in flight and engines operating on the test stand. It was observed that these differences can be reduced by the use of an inflow control structure (ICS) in the static test configuration. The results of the third phase of a three phase program are described. The work performed in the first two phases which dealt with the development of a model for atmospheric turbulence, studies of fan noise generated by rotor turbulence interaction, and the development of an inflow control structure design system are summarized. The final phase of the program covers procedures for performing static testing with an ICS projecting the resulting static test data to actual flight test data. Included is a procedures report which covers the design system and techniques for static testing and projecting the static data to flight.

Peracchio, A. A.↗

NASA NTRS1979

Analytical models for use in fan inflow control structure design. Inflow distortion and acoustic transmission models

Analytical models were developed to study the effect of flow contraction and screening on inflow distortions to identify qualitative design criteria. Results of the study are that: (1) static testing distortions are due to atmospheric turbulence, nacelle boundary layer, exhaust flow reingestion, flow over stand, ground plane, and engine casing; (2) flow contraction suppresses, initially, turbulent axial velocity distortions and magnifies turbulent transverse velocity distortions; (3) perforated plate and gauze screens suppress axial components of velocity distortions to a degree determined by the screen pressure loss coefficient; (4) honeycomb screen suppress transverse components of velocity distortions to a degree determined by the length to diameter ratio of the honeycomb; (5) acoustic transmission loss of perforated plate is controlled by the reactance of its acoustic impedance; (6) acoustic transmission loss of honeycomb screens is negligible; and (7) a model for the direction change due to a corner between honeycomb panels compares favorably with measured data.

Gedge, M. R.↗