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

Why?

• Why?

• Combustion, propulsion, chemical and other industrial problems

• How?

• Create SHI – Stationary, (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