Development and Initial Evaluation of an Acoustic Apparatus Used For Testing of Farfield Noise Emitted by a Propeller in a Short Duct
| العنوان: | Development and Initial Evaluation of an Acoustic Apparatus Used For Testing of Farfield Noise Emitted by a Propeller in a Short Duct |
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| المؤلفون: | Oleson, R. Duane |
| تفاصيل مُضافة: | Patrick, H.V.L. advisor Embry-Riddle Aeronautical University. Department of Aerospace Engineering. Howard Patrick Allen Ormsbee Charles Eastlake Oleson, R. Duane |
| Call Numbers: | TL706.N6 O447 1997eb |
| وصف مادي: | 1 online resource (x, 137 leaves) : illustrations |
| مستخلص: | The purpose of this thesis was to design, construct and evaluate an apparatus which was used for testing of acoustic emissions by a propeller in a short duct. An apparatus was designed based on a combination of acoustic principles and a desire to be able apply the knowledge gained to a practical application such as an ultralight aircraft in an effort to reduce the overall noise levels emitted. The apparatus consisted of a 35 horsepower ultralight engine, a four bladed ultralight propeller, and a duct constructed of a foam core covered with fiberglass. Initial evaluations compared noise levels from the apparatus both with and without the shroud in place, as well as various engine silencer configurations. The data gathered proved the apparatus was actually about 6 dB louder with the shroud than without the shroud as a result of strong rotor-stator interactions. Based on the initial evaluations, this apparatus demonstrated its potential for further testing and acoustical work in the principles of rotor-stator interactions, short duct acoustics, and active noise control applications with the long range goal being to reduce the acoustic emissions from propeller driven aircraft. |
| الموضوعات: | Airplanes Noise., Propellers, Aerial., Noise control., Avions Bruit., Hélices (Aéronautique), Bruit Lutte contre., noise control., Airplanes Noise, Noise control, Propellers, Aerial |
| مصطلحات الفهرس: | Aerospace Engineering |
| URL: | |
| الإتاحة: | Open access content. Open access content |
| ملاحظة: | Also available in print. "Daytona Beach, Florida, April 1997." Includes bibliographical references (leaves 87-88). Acknowledgements ; Abstract ; Table of contents ; List of tables ; List of figures -- 1. Introduction. 1.1. Background ; 1.2. Theory. 1.2.1. Active noise control theory ; 1.2.2. Basic duct theory and cutoff concepts. 1.2.2.1. One dimensional duct ; 1.2.2.2. Axisymmetric ducts ; 1.2.3. Rotor-stator interaction tones ; 1.3. Past work. 1.3.1. Shrouded propellers ; 1.3.2. ANC in ducts ; 1.4. Purpose of the project -- 2. Apparatus, procedure, and initial data. 2.1. Apparatus. 2.1.1. Overview ; 2.1.2. Engine and propeller ; 2.1.3. Shroud ; 2.2. Data acquisition. 2.2.1. Instrumentation ; 2.2.2. Procedures ; 2.2.3. Verification of recorded bandwidth ; 2.3. Initial data analysis. 2.3.1. Performance data ; 2.3.2. Power-spectrum plots -- 3. Results. 3.1. Without shroud. 3.1.1. OASPL tones ; 3.1.2. Frequency spectra. 3.1.2.1. Propeller tones ; 3.1.2.2. Engine tones ; 3.1.3. Nearfield noise ; 3.2. Shroud in place. 3.2.1. OASPL measurements ; 3.2.2. Frequency spectra. 3.2.2.1. Rotor-stator tones ; 3.2.2.2. Engine tones ; 3.2.3. Nearfield Mikes ; 3.3. Engine noise -- 4. Implications from the results. 4.1. Rotor-stator interaction investigation ; 4.2. Future application of ANC -- 5. Conclusions and future recommendations. 5.1. Conclusions ; 5.2. Future recommendations. 5.2.1. Survey of complete apparatus ; 5.2.2. Rotor-stator evaluation ; 5.2.3. ANC installation -- References -- Appendix. A. ROTAX 377 engine specifications and accessories ; B. Coordinated for modified NACA 4312 airfoil ; C. Procedures for construction of shroud ; D. Comparison of A-weighted data to linear data ; E. Test instrumentation and equipment part numbers ; E. Test instrumentation and equipment part numbers ; F. Spectral plots of acoustical data. |
| أرقام أخرى: | FER oai:commons.erau.edu:db-theses-1225 1014343308 |
| المصدر المساهم: | From OAIster®, provided by the OCLC Cooperative. |
| رقم الأكسشن: | edsoai.on1014343308 |
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