Prediction of Noise Field of a Propfan at Angle of Attack [chapter]

Edmane Envia
1993 Unsteady Aerodynamics, Aeroacoustics, and Aeroelasticity of Turbomachines and Propellers  
A method for predicting the noise field of a propfan operating at angle of attack to the oncoming flow is presented. The method takes advantage of the high-blade-count of the advanced propeller designs to provide an accurate and efficient formula for predicting their noise field. The formula, which is written in terms of the Airy function and its derivative, provides a very attractive alternative to the use of numerical integration. A preliminary comparison shows rather favorable agreement
more » ... able agreement between the predictions from the present method and the experimental data. Lighthill stress tensor. S(r) and V(r) represent the propeller blade surfaces and the volume surrounding the blades: respectively: ni's:are components of the outward unit normal to S. It should be noted that the convention for the direction of the unit normal is opposite that of Goldstein's. The medium Form Approved REPORT DOCUMENTATION PAGE OMB No. 0704-0188 Public reporting burden for this¢ctlectlonof Information Is estimated to average 1 hour per response, Includingthe time for revlewlng instructions,searching existingdata sources, gaihedng and maintainingthe data needed, and com#ofing and reviewingthe collectionof information. Send comments regardingthis burden estimate or any other aspect of this collectionof information,Including suggestions for redudng this burden,to Washington HeadquartersServices, Diredorate for informationOperationsand Reports, 1215 Jefferson Davia Highway, Suite 1204, Arlington,VA 22202-4302, and to the Office of Managementand Budget, PaperworkReduction Project (0704-0188), Washington,DC 20503. 14. SUBJECT TERMS Propeller noise; Angle of attack; Moving medium formulation; Uniform asymptotic expansion; Asymptotic formula; Perturbation method 17. SECURITY CLASSIFICATION OF REPORT Unclassified NSN 7540-01-280-5500 18. SECURITY CLASSIFICATION OF THIS PAGE Unclassified 19. SECURITY CLASSIFICATION OF ABSTRACT Unclassified 15. NUMBER OF PAGES 22 16. PRICE CODE A03 20. LIMITATION OF ABSTRACT Standard Form 298 (Rev. 2-8g) Prescribed by ANSI Std. Z39-18 298-102
doi:10.1007/978-1-4613-9341-2_35 fatcat:ctxjiilotfajpoez7kpw2ujpsq