Abstract
An experimental investigation of the propagation of turbulent spots occurring naturally during boundarylayer transition was conducted. Wide-bandwidth heat-transfer instrumentation was used in tracking individual cuibulent spots as they progressed down a flat-plate surface toward fully-developed turbulence. The convection rates of the turbulent/non-turbulent interfaces of the spots in the streamwise direction were determined, as were rates of lateral spreading. The separate effects of compressibility and favourable pressure gradients have been assessed, and some typical results have been reported.
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Abbreviations
- C ie, C_le:
-
fractional propagation rate of the spot leading edge,U le/U∞
- C m, C_m:
-
fractional propagation rate of the spot (“mean”),U m/U∞
- C te, C_te:
-
fractional propagation rate of the spot trailing edge,U te/U∞
- Cr :
-
criterion function
- D :
-
detector function
- dx :
-
distance of propagation of the lateral edge of a turbulent spot in the streamwise direction (mm)
- dz :
-
distance of propagation of the lateral edge of a turbulent spot in the cross-stream direction (mm)
- h :
-
sampling period (s)
- K :
-
acceleration parameter, (ν/U 2∞ )dU ∞/dx
- m :
-
relative signal magnitude
- M ∞ :
-
freestream Mach number
- n :
-
turbulent-spot generation rate (s−1 m−1)
- P :
-
freestream static pressure (N/m2)
- P 0 :
-
total pressure (N/m2)
- q :
-
heat flux (kW/m2)
- Re u :
-
freestream unit Reynolds number at the working-section inlet (m−1),U ∞/ν
- Re θ :
-
local Reynolds number based on momentum thickness,U ∞θ/ν
- T 0 :
-
total temperature (K)
- T w :
-
wall temperature (K)
- Tu :
-
freestream turbulence intensity,u′/U ∞
- t NT :
-
amount of time an unsteady heat-transfer signal is non-turbulent (s)
- t T :
-
amount of time an unsteady heat-transfer signal is turbulent (s)
- U le :
-
turbulent-spot leading-edge velocity (m/s)
- U m :
-
turbulent-spot “mean” velocity (m/s)
- U te :
-
turbulent-spot trailing velocity (m/s)
- U ∞ :
-
local freestream velocity (m/s)
- w :
-
weighting factor
- x :
-
distance from the leading edge of the flat plate (m)
- x 1 :
-
distance from the leading edge of the flat plate to the point of transition onset (m)
- α:
-
turbulent-spot spreading angle (degrees)
- γ:
-
intermittency,t T/(tT+tNT)
- θ:
-
boundary-layer momentum thickness (m)
- ν:
-
kinematic viscosity (m2/s)
- σ:
-
Emmons' non-dimensional turbulent-spot propagation parameter
- τ 5 :
-
smoothing period (s)
References
H.W. Emmons, The laminar-turbuent transition in a boundary layer-part 1.Journal of Aeronautical Sciences 18 (1951) 490–498.
J.J. Riley and M. Gad-el-Hak, The dynamics of turbulent spots. In:Frontiers in Fluid Mechanics. Berlin: Springer-Verlag Publishers (1985) pp. 123–155.
G.B. Schubauer and P.S. Klebanoff, Contributions on the mechanics of boundary layer transition. NACA TN-3489 (1956).
O. Savas,Some measurements in synthetic turbulent boundary layers. Ph.D. Thesis, California Institute of Technology (1979).
B. Cantwell, D. Coles, and P. Dimotakis, Structure and entrainment in the plane of symmetry of a turbulent spot.Journal of Fluid Mechanics 87 (1978) 641–672.
I. Wygnanski, M. Sokolov, and D. Friedman, On a turbulent ‘spot’ in a laminar boundary layer.Journal of Fluid Mechanics 78 (1976) 785–819.
T.S. Mautner and C.W. Van Atta, Wall shear stress measurements in the plane of symmetry of a turbulent spot.Experiments in Fluids 4 (1986) 153–162.
I. Wygnanski, The effects of Reynolds number and pressure gradients on the transitional spot in a laminar boundary layer. In: J. Jimenez (ed.)Lecture Notes in Physics, Berlin: Springer-Verlag Publishers 136 (1981) pp. 304–322.
Y. Katz, A. Seifert, and I. Wygnanski, On the evolution of a turbulent spot in a laminar boundary layer with a favourable pressure gradient.Journal of Fluid Mechanics 221 No. 12 (1990) 1–22.
R. Sankaran and R.A. Antonia, Influence of a favourable pressure gradient on the growth of a turbulent spot.AIAA Journal 26 No. 7 (1988) 885–887.
M. Gad-el-Hak, R.F. Blackwelder, and J.J. Riley, On the growth of turbulent regions in laminar boundary layers.Journal of Fluid Mechanics 110 (1981) 73–95.
T. Matsui, Visualization of turbulent spots in the boundary layer along a flat plate in a water flow. In: R. Eppler and H. Fasel (eds.)Laminar-Turbulent Transition. Berlin: Springer-Verlag Publishers (1980) pp. 288–296.
D.L. Schultz and B.J. Bellhouse, Determination of mean and dynamic skin friction, separation, and transition in low-speed flow with a thin-film heated element.Journal of Fluid Mechanics 24 (1966) 379–400.
F.K. Owen, Transition experiments on a flat plate at subsonic and supersonic speeds.AIAA Journal 8 No. 3 (1970) 518–523.
D.J. Doorly, M.L.G. Oldfield, and C.T.J. Scrivener, Wake-passing in a turbine rotor cascade. In:Heat Transfer and Cooling in Gas-Turbine Engines. Agard CP-390 (1985) Paper No. 7.
J.E. LaGraff, D.A. Ashworth, and D.L. Schultz, Measurement and modelling of the gas turbine transition process as disturbed by wakes.ASME Journal of Turbomachinery 111 (1989) 162–168.
R.P. Shiply, N.T. Birch, H. Riedel, K.H. Horstmann, and P. Lücking, A European Collaborative NLF Nacelle Flight Demonstrator. In:Proceedings of the 1st European Forum on Laminar-Flow Technology. Hamburg: (1992). Also In:Aviation Week and Space Technology 21 No. 12 (1992).
N. Bown, T.M. Cain, P.J. Magari, and T.V. Jones, Analysis of NLF testing. Oxford University O.U.E.L. Report (1993).
T.V. Jones, D.L. Schultz, and A.D. Hendley, On the flow in an isentropic light piston tunnel.ARC 34217 (1973).
J.P. Clark, P.J. Magari, T.V. Jones, and J.E. LaGraff, Experimental studies of turbulent-spot parameters using thin-film heat-transfer gauges.AIAA Paper No. 93-0544 (1993).
D.L. Schultz and T.V. Jones, Heat transfer measurements in short-duration hypersonic facilities.NATO Agardograph 165 (1973).
M.L.G. Oldfield, H.J. Burd, and N.G. Doe, Design of wide-bandwidth analogue circuits for heat-transfer instrumentation in transient tunnels. In:Proceedings of the 16th Symposium of ICHMT. Dubrovnik: Hemisphere Publications (1982).
R. Narasimha, The laminar-turbulent transition zone in the boundary layer.Progress in Aerospace Sciences 22 (1985) 29–80.
T.B. Hedley and J.F. Keffer, Turbulent/non-turbulent decisions in an intermittent flow.Journal of Fluid Mechanics 64 (1974) 645–678.
J.P. Clark, T.V. Jones, D.A. Ashworth, and J.E. LaGraff, Turbulent-spot development in a Mach 0.55 flow. In:Proceedings of the Royal Aeronautical Society Boundary Layer Transition and Control Conference (1991) Paper No. 21.
R. Narashimha, Recent advances in the dynamics of the transition zone.ISABE Paper No. 91-7006 (1991).
D.J. Doorly and F.T. Smith, Initial-value problems for spot disturbances in incompressible and compressible boundary layers.Journal of Engineering Mathamatics 26 (1992).
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Clark, J.P., Jones, T.V. & LaGraff, J.E. On the propagation of naturally-occurring turbulent spots. J Eng Math 28, 1–19 (1994). https://doi.org/10.1007/BF02383602
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DOI: https://doi.org/10.1007/BF02383602