Propagation of sound waves through a blade row: I. Analysis based on the semi-actuator disk theory
TL;DR: In this article, the transmission and reflection coefficients of axial-flow compressor ducts were studied theoretically using semi-actuator disk theory, and the effects of flow Mach number, angle of incidence, wavelength and stagger angle on sound propagation were investigated.
About: This article is published in Journal of Sound and Vibration.The article was published on 1970-03-01. It has received 95 citations till now. The article focuses on the topics: Mach number & Wavelength.
Citations
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01 Aug 1991
TL;DR: In this article, aeroacoustic related problems are evaluated, and approaches to their solutions are suggested without extensive tables, nomographs, and derivations, focusing on underlying physical concepts.
Abstract: Methodology recommended to evaluate aeroacoustic related problems is provided, and approaches to their solutions are suggested without extensive tables, nomographs, and derivations. Orientation is toward flight vehicles and emphasis is on underlying physical concepts. Theoretical, experimental, and applied aspects are covered, including the main formulations and comparisons of theory and experiment. The topics covered include: propeller and propfan noise, rotor noise, turbomachinery noise, jet noise classical theory and experiments, noise from turbulent shear flows, jet noise generated by large-scale coherent motion, airframe noise, propulsive lift noise, combustion and core noise, and sonic booms.
129 citations
TL;DR: In this paper, the effect of blade spacing on sound propagation through a blade row with finite blade spacing is investigated theoretically, in which the kernel function of the aerodynamic integral equation is expressed by several series of the exponential functions, under which many circumferential modes propagate as the transmitted wave and reflected wave for one mode of incident waves.
113 citations
TL;DR: In this article, the transmission and reflection of plane sound waves incident upon a single cascade of finite plates is solved by means of the finite Wiener-Hopf technique, and the results are given in explicit form containing an infinite number of constants.
78 citations
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: In this paper, it was shown that the acoustic resonance is an axial standing wave of a spinning acoustic mode with three periods around the circumference of the compressor, which occurs only if the aerodynamic load in the compressor is high, because the mode needs a high circumferential Mach number for resonance conditions.
Abstract: Nonharmonic acoustic resonance was detected in the static pressure and sound signals in a four-stage high-speed axial compressor when the compressor was operating close to the surge limit. Based on prior research reported in the literature and measurements of the resonance frequency, Mach number of the mean flow, and the axial and circumferential phase shifts of the pressure signal during resonance, it is shown that the acoustic resonance is an axial standing wave of a spinning acoustic mode with three periods around the circumference of the compressor. This phenomenon occurs only if the aerodynamic load in the compressor is high, because the mode needs a high circumferential Mach number for resonance conditions. Mathematics of existing analyses of acoustic resonances in turbomachinery complex and have therefore rarely resulted in published examples of good agreement with real engine data. The present paper provides suitable, physically based simplifications of the existing mathematical models which are applicable for modes with circumferential wavelengths of more than two blade pitches and resonance frequencies considerably higher than the rotor speed.
60 citations
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01 Feb 1958
36 citations
33 citations
28 citations
TL;DR: In this paper, the effect of the presence of the walls is shown to be very significant near the resonant frequency and, for certain conditions, to be large even at frequencies well removed from resonance.
Abstract: The problem of the determination of the air forces on an oscillating airfoil between plane walls has, until recently, been treated only for incompressible flow. The present paper is concerned with the important effects of compressibility, which may be of significance in such problems as the measurement of oscillating air forces or of wing flutter characteristics in wind tunnels, and in the flutter of airfoils in cascade. The possibility of the existence of an acoustic resonance phenomenon under certain critical conditions is discussed. The integral equation for the compressible case, as obtained by Runyan and Watkins in NACA T N 2552, is reviewed briefly and a method of solving the equation is given. The procedure is applied to a number of selected cases at various Mach numbers and tunnel heights. The effect of the presence of the walls is shown to be very significant near the resonant frequency and, for certain conditions, to be large even at frequencies well removed from resonance.
25 citations