Engineering topics

Gliebe, Philip R.

Publications and source records attributed to Gliebe, Philip R..

4 records

NASA NTRS2003

Ultra-High Bypass Engine Aeroacoustic Study

A system study was carried out to identify potential advanced aircraft engine concepts and cycles which could be capable of achieving a 5 to 10 EPNdB reduction in community noise level relative to current FAR36 Stage 3 limits for a typical large-capacity commercial transport aircraft. The study was directed toward large twin-engine aircraft applications in the 400,000 to 500,000 pound take-off gross weight class. Four single rotation fan engine designs with fan pressure ratios from 1.3 to 1.75, and two counter-rotating fan engine configurations were studied. Several engine configurations were identified which, with further technology development, could achieve the objective of 5 to 10 EPNdB noise reduction. Optimum design fan pressure ratio is concluded to be in the range of 1.4 to 1.55 for best noise reduction with acceptable weight and Direct Operating Cost (DOC) penalties.

Gliebe, Philip R.↗

NASA NTRS2003

Aircraft engine with inter-turbine engine frame supported counter rotating low pressure turbine rotors

An aircraft gas turbine engine assembly includes an inter-turbine frame axially located between high and low pressure turbines. Low pressure turbine has counter rotating low pressure inner and outer rotors with low pressure inner and outer shafts which are at least in part rotatably disposed co-axially within a high pressure rotor. Inter-turbine frame includes radially spaced apart radially outer first and inner second structural rings disposed co-axially about a centerline and connected by a plurality of circumferentially spaced apart struts. Forward and aft sump members having forward and aft central bores are fixedly joined to axially spaced apart forward and aft portions of the inter-turbine frame. Low pressure inner and outer rotors are rotatably supported by a second turbine frame bearing mounted in aft central bore of aft sump member. A mount for connecting the engine to an aircraft is located on first structural ring.

Seda, Jorge F.↗

NASA NTRS1996

Improved NASA-ANOPP Noise Prediction Computer Code for Advanced Subsonic Propulsion Systems: Fan Suppression Model Development - Volume 2

The Aircraft Noise Predication Program (ANOPP) is an industry-wide tool used to predict turbofan engine flyover noise in system noise optimization studies. Its goal is to provide the best currently available methods for source noise prediction. As part of a program to improve the Heidmann fan noise model, models for fan inlet and fan exhaust noise suppression estimation that are based on simple engine and acoustic geometry inputs have been developed. The models can be used to predict sound power level suppression and sound pressure level suppression at a position specified relative to the engine inlet.

Kontos, Karen B.↗

NASA NTRS1995

UHB Engine Fan Broadband Noise Reduction Study

A study has been completed to quantify the contribution of fan broadband noise to advanced high bypass turbofan engine system noise levels. The result suggests that reducing fan broadband noise can produce 3 to 4 EPNdB in engine system noise reduction, once the fan tones are eliminated. Further, in conjunction with the elimination of fan tones and an increase in bypass ratio, a potential reduction of 7 to 10 EPNdB in system noise can be achieved. In addition, an initial assessment of engine broadband noise source mechanisms has been made, concluding that the dominant source of fan broadband noise is the interaction of incident inlet boundary layer turbulence with the fan rotor. This source has two contributors, i.e., unsteady life dipole response and steady loading quadrupole response. The quadrupole contribution was found to be the most important component, suggesting that broadband noise reduction can be achieved by the reduction of steady loading field-turbulence field quadrupole interaction. Finally, for a controlled experimental quantification and verification, the study recommends that further broadband noise tests be done on a simulated engine rig, such as the GE Aircraft Engine Universal Propulsion Simulator, rather than testing on an engine statically in an outdoor arena The rig should be capable of generating forward and aft propagating fan noise, and it needs to be tested in a large freejet or a wind tunnel.

Gliebe, Philip R.↗