Drag Coefficients of Spheres in Hypersonic Non-Continuum Flow PDF Download
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Author: John F. Wendt
Publisher:
ISBN:
Category :
Languages : en
Pages : 43
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Book Description
A modulated force probe with a sensitivity in the microgram range was employed to measure the drag forces on spheres in the Mach 5 range with an R.M.S. error of + or - 1%. Flow properties in the free jet were used to calculate sphere drag coefficients. The resulting values cover the flow regimes from near-free-molecule to transitional. A correlation parameter - an 'effective' Knudsen number based on body-free stream molecular collisions - is shown to provide a reasonable correlation for a large variety of sphere drag measurements.
Author: John F. Wendt
Publisher:
ISBN:
Category :
Languages : en
Pages : 43
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Book Description
A modulated force probe with a sensitivity in the microgram range was employed to measure the drag forces on spheres in the Mach 5 range with an R.M.S. error of + or - 1%. Flow properties in the free jet were used to calculate sphere drag coefficients. The resulting values cover the flow regimes from near-free-molecule to transitional. A correlation parameter - an 'effective' Knudsen number based on body-free stream molecular collisions - is shown to provide a reasonable correlation for a large variety of sphere drag measurements.
Author: MAX. KINSLOW
Publisher:
ISBN:
Category :
Languages : en
Pages : 58
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Drag of spheres was measured under hypersonic, cold-wall, support-free conditions in a nonreacting (vibration frozen) flow. Data were obtained for a nominal free-stream Mach 11 and for Reynolds numbers from 1 to 10 based on conditions immediately downstream of the bow shock and sphere diameter. These data were supplemented by measurements at a nominal Mach 10 where a conventional balance was used, and Reynolds numbers downstream of the shock as high as 10,000 were investigated in the cold-wall condition. The experimental results were analyzed both from the point of view of continuum flow with second-order viscous effects, and from the standpoint of a noncontinuum concept, taking account of first collisions between reemitted and free-stream molecules. Data from other sources were used to enlarge the present study and, in particular, to support the evaluation of K2 which represents the influences of vorticity, curvature, thick boundary layer, slip, and temperature jump. K2 was found to be negative in sign. The form of the derived equation for Cd/Cd(free molecular), where Cd is the drag coefficient, Cd/Cd free molecular appears to fit the experimental data over a considerable range of Knudsen numbers if a free constant is used in the expression for mean free path. (Author).
Author: David J. Masson
Publisher:
ISBN:
Category : Atmospheric density
Languages : en
Pages : 38
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Author: Neil Arthur Zarin
Publisher:
ISBN:
Category : Drag (Aerodynamics)
Languages : en
Pages : 148
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Author:
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ISBN:
Category : Aeronautics
Languages : en
Pages : 520
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Author: A. B. Bailey
Publisher:
ISBN:
Category :
Languages : en
Pages : 97
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A comprehensive set of measurements was made in a ballistic range which permits the sphere drag coefficient to be derived with an uncertainty of approximately +2 or -2 percent in the flight regime 0.1
Author: Jerome Aroesty
Publisher:
ISBN:
Category : Aerodynamics, Supersonic
Languages : en
Pages : 318
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Book Description
Sphere drag coefficients were measured in the Berkeley Low Density Wind Tunnel at Mach equals 2, 4, and 6, and free stream Reynolds numbers between 10 and 10,000 for both insulated and cold wall conditions. The measurements indicate that sphere drag in this regime is strongly dependent on the Reynolds number behind a normal shock wave, and only weakly dependent on Mach number. In addition, it was found that a decrease in wall temperature/stagnation temperature (T sub w/T sub o) from 1 to 0.26 was accompanied by a 5 - 10% decrease in the drag coefficient. A precision microbalance was used to obtain data for insulated spheres, and a moving model technique was used to obtain data for small spheres falling freely through a wind tunnel jet. These latter tests were performed using both cold and insulated models. The results on insulated spheres at M equal 2 and 4 were in good agreement with the measurements of other investigators. The results of the cold wall tests indicate that for Mach numbers greater than 5 in air, sphere drag coefficients are a function only of T sub w/T sub o and the post normal shock Reynolds number. (Author).
Author: C. R. Ortloff
Publisher:
ISBN:
Category :
Languages : en
Pages : 12
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A survey of numerical results of low-density transitional regime drag coefficients and number density distributions about slender, cold-wall, conical vehicles at hypersonic speeds is presented. The transitional regime results have been obtained from numerical solutions of Rosen's restricted variational principle representation of the Boltzmann equation, which has been shown to be equivalent at Galerkin's method of solution of operator equations. Transitional regime drag coefficients are compared with near free molecule and viscous interaction predictions of drag coefficients. Number density profiles for the transitional regime are also given and compared with known qualitative features of near continuum flow fields to assess the validity of results obtained by the variational method. Results indicate that the drag coefficient varies smoothly from known viscous interaction predictions and reaches the limiting value of 2 when the freestream Knudsen number is on the order of unity for the class of slender cones considered. A decrease of cone-half-angle, with Knudsen number fixed, results in a steeper rise of the drag coefficient curve toward the limiting high Knudsen number value of 2. For cone half-angles on the order of 5 degrees, the drag coefficient curve exhibits an overshoot over the free molecule value. (Author).
Author:
Publisher:
ISBN:
Category : Science
Languages : en
Pages : 86
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Author: A. S. Hersh
Publisher:
ISBN:
Category : Aerodynamics
Languages : en
Pages : 44
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