Unsteady Aerodynamic Reactions on Airfoils in Cascade
01 May 1955-Journal of the Aeronautical Sciences (American Institute of Aeronautics and Astronautics (AIAA))-Vol. 22, Iss: 5, pp 297-302
About: This article is published in Journal of the Aeronautical Sciences.The article was published on 1955-05-01. It has received 14 citations till now. The article focuses on the topics: Airfoil & Camber (aerodynamics).
Citations
More filters
TL;DR: The history of research on rotating blade noise is reviewed in this paper, from early studies of propeller radiation to current work on aircraft-engine fans, with emphasis on fundamental aspects of aerodynamic sound generation by blades.
65 citations
TL;DR: The applicability of the vortex method to cascades of oscillating airfoils is assessed by computing the unsteady incompressible lift, drag, and moment for small incidence, thickness, and vibratory displacement as discussed by the authors.
Abstract: The applicability of the vortex method to cascades of oscillating airfoils is assessed by computing the unsteady incompressible lift, drag, and moment for small incidence, thickness, and vibratory displacement—the so-called "classical" case. The results for a limited sampling of cascade geometries, reduced frequencies, vibration amplitudes, and interblade phase angles are in excellent agreement with available analytical results. Instantaneous streamline patterns and discretized vorticity distributions are presented as an aid in physical understanding. The importance of the interblade phase angle as a governing parameter is confirmed. Then the effects of mean incidence, vibration amplitude, and stagger angle are studied. Important new results are presented showing the evolution of the classical reactions into the stalled-flow reactions with incidence, frequency, and amplitude as parameters. In particular, the complicated interaction is demonstrated between the structural frequency of the blades (considered as one of the "inputs" to a nonlinear aeroelastic system) and the output frequency spectrum of the aerodynamic reactions. The implications for future direction of research and design code implementation are discussed.
20 citations
TL;DR: In this article, a modified form of the vortex method is used to simulate the flow over an infinite linear cascade of airfoils, and a computational scheme based on a modified version of the Vortex Method is presented.
Abstract: At off-design conditions turbomachines may experience flow separation from the cascaded airfoils and the circumferential pattern of stalled and unstalled airfoils propagates about the flow annulus. The unsteady periodic nature of propagating stall will force blade vibration; stall flutter of the blades may occur if stall synchronization occurs and the propagation frequency is entrained by the blade natural frequency. A computational scheme based on a modified form of the vortex method is used to simulate the flow over an infinite linear cascade of airfoils.
16 citations
01 Jan 2017
TL;DR: In this article, the authors focus on the flow-acoustics of axial flow machinery from helicopter blades to automotive cooling fans, and consider the special acoustic considerations brought about by the rotational motion of the blades relative to the acoustic medium.
Abstract: This chapter focuses on the flow-acoustics of axial flow machinery from helicopter blades to automotive cooling fans. This chapter will consider the special acoustic considerations brought about by the rotational motion of the blades relative to the acoustic medium; that multiple flow excitations may coexist, providing varied spectral quality in different frequency ranges; the modifications of blade forces owing to the interactions of blades in the rotor with each other and with other blade rows; and the frequency–wave number matching of the rotor with ingested disturbances on the one hand and with acoustical modes of enclosures on the other. The chapter starts with an examination of the fundamental characteristics of unsteady loads and of noise from rotating vanes, before discussing the important performance features of rotating machinery. Free-field rotor noise and self-noise of blades will be described, as well as examining turbulent and deterministic blade interaction sounds due to nonuniform inflow, and the fundamental acoustics of ducted rotors and centrifugal fans.
8 citations
References
More filters
Book•
01 Jan 1902
TL;DR: The volume now gives a somewhat exhaustive account of the various ramifications of the subject, which are set out in an attractive manner and should become indispensable, not only as a textbook for advanced students, but as a work of reference to those whose aim is to extend the knowledge of analysis.
Abstract: This classic work has been a unique resource for thousands of mathematicians, scientists and engineers since its first appearance in 1902 Never out of print, its continuing value lies in its thorough and exhaustive treatment of special functions of mathematical physics and the analysis of differential equations from which they emerge The book also is of historical value as it was the first book in English to introduce the then modern methods of complex analysis This fifth edition preserves the style and content of the original, but it has been supplemented with more recent results and references where appropriate All the formulas have been checked and many corrections made A complete bibliographical search has been conducted to present the references in modern form for ease of use A new foreword by Professor SJ Patterson sketches the circumstances of the book's genesis and explains the reasons for its longevity A welcome addition to any mathematician's bookshelf, this will allow a whole new generation to experience the beauty contained in this text
8,965 citations
119 citations
33 citations
32 citations