Combination of FRS-, PSP-, and LDV measurements to describe the velocity and pressure distributions in the flow around and on the surface of a hemisphere
M. Dues(1), J. Steinbock(1), A. Siswanto(1), S. Melnikov(1), F. Namockel(2), M. Schäferling(2), P. Guntermann(3), H. Hayer(3), U. Doll(4), I. Röhle(5)
1: ILA R&D GmbH, Jülich, Germany
2: FH Münster (FHM), Münster, Germany
3: European Transonic Windtunnel (ETW), Köln, Germany
4: Department of Mechanical and Production Engineering, Aarhus University, Denmark
5: Fachbereich II, Berliner Hochschule für Technik, Germanny
DOI:
This article presents the combination of three optical measurement techniques—Filtered Rayleigh Scattering (FRS), Pressure Sensitive Paint (PSP), and Laser Doppler Velocimetry (LDV) — applied to a test object of particular interest for fundamental research: the hemisphere. In addition to the compelling measurement data, a comparison of the velocity data obtained via FRS and LDV is presented. The pressure distribution on the surface is recorded using pressure-sensitive paint (PSP) that is illuminated in the UV range. The dye emits light with a wavelength of around 650 nm, its intensity depends on the static pressure or the oxygen concentration. The velocity and pressure distribution in a cross-sectional plane behind the hemisphere is measured using the frequency scanning filtered Rayleigh scattering method (fs-FRS), which allows the planar detection of the velocity, pressure, and temperature distribution in the flow. The reconstructed FRS velocity is validated with Laser Doppler Velocimetry (LDV) measurements. 25 20 m/s 25 20 local pressure 20 15 1.00 950 15 y in mm y in mm 0.75 10 940 0.50 10 pressure in hPa 0.25 930 5 0.00 5 x/D 920 0.25 0 0 30 20 10 0 10 20 30 0.50 910 30 20 10 0 10 20 30 x in mm 0.75 x in mm 900 1.00 2 1 0 1 2 3 890 z/D 12 0 12 24 36 48 60 12 0 12 24 36 48 60 axial velocity in m/s (LDA) axial velocity in m/s Figure 1. Geometric Figure 3. Surface pressure, layout of the halfsphere Figure 2. Vector-plot of Figure 4. Contour-plot of determined by PSP. experiment. the in-plane velocity the axial velocity obtained obtained by FRS. by LDV.
