Why? Why? Combustion, propulsion, chemical and other industrial problems How?



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tarix19.12.2017
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Why?

  • Why?

    • Combustion, propulsion, chemical and other industrial problems
  • How?

    • Create SHIStationary, (nearly) Homogeneous, and (nearly) Isotropic flow and mixing: closed vessels and/or propellers, HEV…
  • The ‘porcupine’: R. Betchov, 1957

  • Synthetic jets’ in cubic chamber - W. Hwang and J.K. Eaton (E. Fluids, 2003)

  • Propellers - Birouk, Sahr and Gokalp (F. Turb. & Comb, 2003)

  • Synthetic jets - J.P. Marié

  • French Washing Machine



























III. DESCRIPTION of the FLOW: fluctuating field; local approach;

  • 3-rd order SF

  • 2-nd order SF with the Kolmogorov constant Ck=2 ..

  • Normalized dissipation which L? Attention to initial conditions versus universality .. However, a reliable test

  • The most reliable test is the 1—point energy budget equation, when the pressure-related terms could be neglected (point II).







III. DESCRIPTION of the FLOW: fluctuating field; PIV for determining small scale properties

  • The other tests

  • 2-rd order SF with the Kolmogorov constant

  • Normalized dissipation which L? Attention to initial conditions versus universality .. However, a reliable test

  • for

  • The most reliable test is the 1—point energy budget equation, when the pressure-related terms might be neglected (point II).



III. DESCRIPTION of the FLOW: fluctuating field; back to PIV for determining small scale properties



III. DESCRIPTION of the FLOW: fluctuating field; back to PIV for determining small scale properties



III. DESCRIPTION of the FLOW: fluctuating field; back to PIV for determining small scale properties



III. DESCRIPTION of the FLOW: fluctuating field; back to PIV for determining small scale properties







III. DESCRIPTION of the FLOW: fluctuating field; LDV for determining small scale properties

  • a) LDV in 1 point  mean velocity, RMS, small-scales quantities (definitions, correlations, SF2, SF3, 1-point energy budget equation… ). Good to determine the RMS and to compare with the PIV results (15% difference).

  • Drawback: Taylor’s hypothesis is needed, in a flow where the turbulence intensity varies from 100% to infinity (stagnation points ..).

  • LDV in two points simultaneous measurements of one velocity component in 2 spatial points (separation parallel to the measured velocity direction)… many points.

  • Different methods: SF2, SF3, definition of

  • 1-point energy budget equation (pressure … good for point II).



















Results




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