Simplified Laminar Boundary-Layer Calculations for Bodies of Revolution and Yawed Wings

Rott, Nicholas; Crabtree, L. F.

doi:10.2514/8.2381

Cited by 59 publications

(4 citation statements)

References 20 publications

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“…The value of 8 , is a function of the particular headform and the wetted surface velocity distribution. Using the pressure distributions given by Brennen ( 1968) for the wetted surface of a cavitating sphere and the approximate integral method of Rott & Crabtree (1952) 8, was found to be given by I,/(Ru/U) (R and v being the radius of the sphere and the kinematic viscosity) where I was estimated as 0.3, varying negligibly with cavitation number within the range 0 < r < 0.4.…”

Section: MI = 2tt(cmmentioning

confidence: 99%

The dynamic balances of dissolved air and heat in natural cavity flows

Brennen

1969

J. Fluid Mech.

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In steady, fully developed and unventilated cavity flows occurring in practice, air (originally dissolved in the water) and heat are diffused through the fluid towards the interface providing a continuous supply of air and vapour to the cavity. This must be balanced by the rate of entrainment of volume of air and vapour away from the cavity in the wake. These equilibria which determine respectively the partial pressure of air within the cavity and the temperature differences involved in the flow are studied in this paper. The particular case of the cavitating flow past a spherical headform has been investigated in detail. Measurements indicate a near-linear relation between the partial pressure of air in the cavity and the total air content of the water. From a second set of experiments, designed to estimate the volume rates of entrainment under various conditions by employing artificial ventilation, it appears that this is a function only of tunnel speed and cavity size within the range of the experiments. A simplified theoretical approach involving the turbulent boundary layer on the surface of the cavity is then used to estimate the rates of diffusion into the cavity. The resulting air balance yields a partial pressure of air/air content relation compatible with experiment. The water vapour or heat balance suggests that the temperature differences involved are likely to be virtually undetectable experimentally.

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Section: MI = 2tt(cmmentioning

confidence: 99%

The dynamic balances of dissolved air and heat in natural cavity flows

Brennen

1969

J. Fluid Mech.

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“…A crude estimate of this constant can be obtained either by reducing the axisymmetrical problem to a Falkner-Skan flow using Mangler's transformation and approximating to the outer flow (for example by threedimensional sink flow) or by applying-since the flow is accelerating-a simple method of the Kkm&n-Pohlhausen type, e.g. Walz's method as extended by Rott & Crabtree (1952) using the pressure distribution near the lip as computed by Frank1 for slit flow.…”

Section: The Euler Limitmentioning

confidence: 99%

Gaskinetics and gasdynamics of orifice flow

Liepmann

1961

J. Fluid Mech.

144

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The paper gives the result of a study on the efflux of gases through circular apertures. The problem is considered as an example of a transition from the gasdynamic to the gaskinetic régime.The mass flow of helium, argon and nitrogen was measured for a range of upstream pressures corresponding to (mean free path)/(aperture diameter) from about 50 to 5 × 10−3; within this range the transition from molecular effusion to inviscid, transonic flow takes place. The theory for the two asymptotic limits is discussed and first-order corrections to the free molecular and inviscid limit formulae are given.

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“…The Reynolds number of the secondary stream was 42,000 for all four cycles; the Reynolds number of the tertiary stream ranged from 17,000 in cycle A to 25,000 in cycle D. These values are low enough to support laminar boundary layers at the exits of the secondary and tertiary streams. A compressible Thwaites method [32] was used to calculate of the boundary-layer thickness by approximating the annular secondary and tertiary ducts as twodimensional. The calculated displacement thickness of the secondary flow is 0.024 mm.…”

Section: Viscous Effectsmentioning

confidence: 99%

Aeroacoustics of Three-Stream High-Speed Jets from Coaxial and Asymmetric Nozzles

Papamoschou

Johnson

Phong

2014

Journal of Propulsion and Power

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The development of three-stream variable-cycle turbofan engines for tactical aircraft provides an opportunity for noise reduction by shaping the exhaust of the secondary and tertiary streams. The paper reviews an experimental study of subscale three-stream jets operating at high specific thrust and issuing from rapid-prototyped nozzles. Exhaust conditions at four set points, with variable tertiary pressure ratio and bypass ratio, were determined using thermodynamic cycle analysis. Nozzles were fabricated for each set point and featured coaxial and non-coaxial exit geometries. The operating conditions were simulated using precisely metered helium-air mixtures, and far-field noise surveys were collected using a 24-microphone array. For a low-bypass ratio, a coaxial configuration offers no significant noise benefit compared to the single-stream primary jet. Configurations with offset secondary or tertiary streams offer significant noise reduction in the direction of the thicker flow. For an overall bypass ratio around 0.5, reductions of 5.1 dB in overall sound pressure level and 4.2 dB in effective perceived noise level were attained.

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Simplified Laminar Boundary-Layer Calculations for Bodies of Revolution and Yawed Wings

Cited by 59 publications

References 20 publications

The dynamic balances of dissolved air and heat in natural cavity flows

The dynamic balances of dissolved air and heat in natural cavity flows

Gaskinetics and gasdynamics of orifice flow

Aeroacoustics of Three-Stream High-Speed Jets from Coaxial and Asymmetric Nozzles

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