A New Look at Sound Generation by Blade/Vortex Interaction

1985 ◽  
Vol 107 (2) ◽  
pp. 224-228 ◽  
Author(s):  
J. C. Hardin ◽  
J. P. Mason
Keyword(s):  
Low Frequency ◽  
Initial Position ◽  
Sound Pulse ◽  
Two Dimensional ◽  
Vortex Interaction ◽  
Dimensional Problem ◽  
Sound Generation ◽  
Blade Vortex Interaction ◽  
Vortex Velocity

As a preliminary attempt to understand the dynamics of blade/vortex interaction, the two-dimensional problem of a rectilinear vortex filament interacting with a Joukowski airfoil is analyzed in both the lifting and nonlifting cases. The vortex velocity components could be obtained analytically and integrated to determine the vortex trajectory. With this information, the aeroacoustic low-frequency Green’s function approach could then be employed to calculate the sound produced during the encounter. The results indicate that the vortex path deviates considerably from simple convection due to the presence of the airfoil and that a reasonably sharp sound pulse is radiated during the interaction whose fundamental frequency is critically dependent upon whether the vortex passes above or below the airfoil. Determination of this gross parameter of the interaction is shown to be highly nonlinearly dependent upon airfoil circulation, vortex circulation, and initial position.

Novel method for calculating two-dimensional blade vortex interaction

AIAA Journal ◽  
1997 ◽  
Vol 35 ◽  
pp. 909-912
Author(s):  
Ronald J. Epstein ◽  
John A. Rule ◽  
Donald B. Bliss
Keyword(s):  
Two Dimensional ◽  
Vortex Interaction ◽  
Blade Vortex Interaction ◽  
Novel Method

scholarly journals On the convection of heat from small cylinders in a stream of fluid: Determination of the convection constants of small platinum wires, with applications to hot-wire anemometry

1914 ◽  
Vol 90 (622) ◽  
pp. 563-570 ◽  
Keyword(s):  
Unit Volume ◽  
Unit Length ◽  
Stream Line ◽  
Two Dimensional ◽  
Dimensional Problem ◽  
Hot Wire ◽  
Stream Lines ◽  
Hydrodynamical Problem ◽  
Uniform Stream

Sections 1 and 2.- Until comparatively recently, the problem of solving the equations of heat conduction in the case of a solid cooled by a stream of fluid had received little attention, although the general problem was formulated by Fourier himself as long ago as 1820. In 1901 the problem was taken up by Boussinesq, and many cases were dealt with in his memoir of 1905. By means of an extremely elegant transformation Boussinesq was able to express the general equation for the two-dimensional problem in a linear form: by transforming the equation to the set of orthogonal curvilinear co-ordinates determined by the stream-lines and equipotentials of the hydrodynamical problem of the flow of a uniform stream of velocity V past the cylindrical obstacle, the equation for the temperature θ at any point of the fluid takes the form ∂ 2 θ /∂ α 2 + ∂ 2 θ /∂ β 2 = 2 n ∂ θ / ∂β , (1) where the curves α = constant represent the stream-lines and β = constant the equipotentials. The constant n is given by the relation 2 n = c V/ k = s σV/ k , where c is the specific heat of the fluid per unit volume, s that per unit mass, σ its density, and k its thermal conductivity. If the surface of the cylinder be the particular stream-line α = 0, and the critical equipotentials be the curves β =o and β = β 0 , the heat-flux per unit length of the cylinder is given by H = -∫ β 0 0 k ∂ θ /∂ α 0 dβ . (2) where the integral is taken to include the two branches of the stream-lines α = 0.

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