| Autor: |
R. D. Cuthbertson, D. P. Johnson, B. N. Shivashankara |
| Rok vydání: |
1990 |
| Předmět: |
|
| Zdroj: |
13th Aeroacoustics Conference. |
| DOI: |
10.2514/6.1990-4023 |
| Popis: |
General Electric has developed an Ultra-high bypass open rotor engine(UDF@’ engine)When Boeing was studying the use this engine with counter rotating propulsors, possible noise increase due to installation on the aft end of the fuselage was one of the concerns. Such noise increase could be due to the inflow distortion and acoustic diffraction. To determine the installation effects, a test of a scale model of the U D e r o puisor was conducted at the German-Dutch wind tunnel (DNW) in Holland. To simulate installation effects, models of pylon, fore-shortened-aft-fuselage and empennage were used. These could be added in various combinations to enable effects of individual items to be determined. A pylon trailing edge blowing technique was tested to reduce the impact of installation effects. The test results showed that the addition of the pylon upstream of the propulsor could increase the front rotor blade passage frequency(BPF) by as much as 10-12 dB with negligible effect on interaction tones. Addition of the fuselage increased the front rotor BPF by an additional 2-3 dB and also impacted the interaction tones. The root-flow at the attachment point of the pylon to the fuselage was also seen as a source of noise increase. BPF of the front rotor was seen to increase monotonically as the pylon was brought close to the propulsor and when the fuselage was moved closer to the propulsor tip. Pylon trailing edge blowing technique was found to be successful in reducing the pylon wake and the root-flow distortion and was capable of bringing the installed configuration front BPF levels back down close to the isolated propulsor levels. Comparison of data taken at Boeing Transonic Wind Tunnel facility with that taken at DNW agreed reasonably well providing confidence in repeatability of model propulsor data and in noise data taken at BTWT with acoustically treated tunnel walls. |
| Databáze: |
OpenAIRE |
| Externí odkaz: |
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