Extension of Emmons' spot theory to flows on blunt bodies

Chen, Karl K.; Thyson, Noel A.

doi:10.2514/3.6281

Cited by 155 publications

(42 citation statements)

References 11 publications

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“…Chen and Thyson [20] discuss a spanwise length scale in the region of transition where the bursts begin to overlap ; that is, where …”

Section: -mentioning

confidence: 99%

“…This is [9] as well as for axisymmetric bodies [20]. Another important mean property -of I(x 1, t) is the "burs t frequency " , N(x 1 ) .…”

Section: (A) This Function Is Zeromentioning

confidence: 99%

“…lam inar flow acoustic pressure boundary layer no i se transition 20. A B51~lA C7 (Continue on reverse side if necessary and identify by block number) (U) ' A theory is presented for the noise radiated by incompressible boundary-layer transition that occurs on an infinite , rigid flat plate.…”

mentioning

confidence: 99%

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On the radiated noise due to boundary-layer transition

Lauchle

1980

The Journal of the Acoustical Society of America

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A theory is presented for the noise radiated by the incompressible boundary-layer transition that occurs on an infinite, rigid flat plate. It is hypothesized that it is the intermittency of the boundary-layer flow within the transition zone that is dominant in noise production. Using Lighthill’s analogy, it is shown that dipole, quadrupole, and octupole sources are generated. The dipole sources are attributable to the shear stress fluctuations that occur in transitional flow while the others are due to fluctuating Reynolds stresses and their images. Under the assumption that dipole sources are more efficient than quadrupoles or octupoles when the Mach number is very small, the power spectrum of the radiated noise due to the dipole contribution is derived. The spectral level rises at 6 dB/octave, peaks at a frequency corresponding to the time it takes for a turbulence burst to convect through the transition region, and then drops off again at 6 dB/octave. The radiation efficiency is analyzed and found to be quite low; it is only 20% of that for a fully developed turbulent boundary-layer flow.

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“…Chen and Thyson [20] discuss a spanwise length scale in the region of transition where the bursts begin to overlap ; that is, where …”

Section: -mentioning

confidence: 99%

“…This is [9] as well as for axisymmetric bodies [20]. Another important mean property -of I(x 1, t) is the "burs t frequency " , N(x 1 ) .…”

Section: (A) This Function Is Zeromentioning

confidence: 99%

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On the radiated noise due to boundary-layer transition

Lauchle

1980

The Journal of the Acoustical Society of America

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“…In a recent paper, Ekaterinaris et al 18 estimated the transition onset location using the empirical Michel's criterion 19 and the transition length using the Chen-Thyson model. 20 This model is based on data for attached flows and gives the turbulent intermittency y tr as Walker et al 21 also used the Chen-Thyson model in combination with a viscous-inviscid interaction method to compute the separation bubble occurring on a NACA 65-213 airfoil in incompressible flow and Re c = 2.4 x 10…”

Section: A Transition Predictionmentioning

confidence: 99%

Analysis of compressible light dynamic stall flow at transitional Reynolds numbers

et al. 1996

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Numerical and experimental results of steady and light dynamic stall flow over an oscillating NACA 0012 airfoil at a freestream Mach number of 0.3 and Reynolds number of 0.54 x 10 6 are compared. The experimental observation that dynamic stall is induced from the bursting of a laminar separation bubble points to the role of transition in influencing the flow development. Its modeling, including the changes in transition onset location and transition length with increase in airfoil angle of attack, is critical for computing the dynamic stall flow properly. In this study, the transition onset point is specified suitably and a simple transition length model is incorporated to determine the extent of the laminar separation bubble. The thin-layer approximations of compressible, Reynolds-averaged, Navier-Stokes equations are used for the numerical solution, with an implicit, upwind-biased, third-order-accurate scheme for the numerical integration. Remarkably good agreement with experiments is obtained in steady flow for the pressure and velocity distributions near the leading edge. Oscillatory airfoil flow results compare favorably on the upstroke, but on the downstroke, the computations do not predict the light stall and vorticity shedding that were observed experimentally.

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“…The correlation was later improved by Gostelow et al (1994) for flows with pressure gradients subject to a range of freestream turbulence intensities. Solomon et al (1995), following the work of Chen and Thyson (1971), developed an improved method to predict transitional flows involving changes in pressure gradients. In this model, the effects of changing streamwise pressure gradient on the breakdown physics and spot spreading rates are taken into account.…”

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confidence: 99%

Predictions of separated and transitional boundary layers under low-pressure turbine airfoil conditions using an intermittency transport equation

Suzen

Huang

Hultgren

et al. 2001

39th Aerospace Sciences Meeting and Exhibit

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A new transport equation for the intermittency factor was proposed to predict separated and transitional boundary layers under low-pressure turbine airfoil conditions. The intermittent behavior of the transitional flows is taken into account and incorporated into computations by modifying the eddy viscosity, µt , with the intermittency factor, y. Turbulent quantities are predicted by using Menter's two-equation turbulence model (SST). The intermittency factor is obtained from a transport equation model, which not only can reproduce the experimentally observed streamwise variation of the intermittency in the transition zone, but also can provide a realistic cross-stream variation of the intermittency profile.In this paper, the intermittency model is used to predict a recent separated and transitional boundary layer experiment under low pressure turbine airfoil conditions. The experiment provides detailed measurements of velocity, turbulent kinetic energy and intermittency profiles for a number of Reynolds numbers and freestream turbulent intensity conditions and is suitable for validation purposes. Detailed comparisons of computational 'Postdoctoral Researcher, Member AIAA. t Associate Professor, Senior Member AIAA.Associate Fellow AIAA § Aerospace Engineer, Senior Member AIAA.

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Extension of Emmons' spot theory to flows on blunt bodies

Cited by 155 publications

References 11 publications

On the radiated noise due to boundary-layer transition

On the radiated noise due to boundary-layer transition

Analysis of compressible light dynamic stall flow at transitional Reynolds numbers

Predictions of separated and transitional boundary layers under low-pressure turbine airfoil conditions using an intermittency transport equation

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