214
9 Characterisation of Flow Properties at the Surface
Fig. 9.21 Principle of oil-film interferometry for skin friction measurement
Fig. 9.22 Oil film method. Measurement of film thickness by interferometry (© ONERA)
The thickness y at any instant t can be measured accurately by an interferometry
technique (see Fig. 9.22) and given as
y =
μ x
τ t
9 Characterisation of Flow Properties at the Surface
Fig. 9.21 Principle of oil-film interferometry for skin friction measurement
Fig. 9.22 Oil film method. Measurement of film thickness by interferometry (© ONERA)
The thickness y at any instant t can be measured accurately by an interferometry
technique (see Fig. 9.22) and given as
y =
μ x
τ t