Frequency scanning filtered Rayleigh scattering is able to simultaneously provide time-averaged measurements of pressure, temperature and velocity in gaseous flows. By extending the underlying mathematical model, a robust alternative to existing approaches is introduced. Present and proposed model functions are then characterized during a detailed uncertainty analysis. Deviations between the analytical solution of a jet flow experiment and measured results could be related to laser-induced background radiation as well as the Rayleigh scattering’s spectral distribution. In applying a background correction method and by replacing the standard lineshape model by an empirical formulation, detrimental effects on pressure, temperature and velocity accuracies could be reduced below 15 hPa, 2.5 K and 2.7 m s−1.
The flow field of a Ranque-Hilsch vortex tube is characterized experimentally. Firstly conventional probe based technology is used in order to measure inlet and outlet temperatures as well as to acquire temporally resolved wall pressure data over a wide range of operating conditions. Secondly the filtered Rayleigh scattering technique is employed in order to gather detailed temporally averaged planar information on the vortex tube's flow topology. These measurements form the basis of a detailed numerical study in part II of this contribution.
ZusammenfassungDie Messung von Temperatur- und Geschwindigkeitsfeldern spielt eine wichtige Rolle sowohl in der Luftfahrt als auch in der Energie- und Verfahrenstechnik. Mit laseroptischen Verfahren können hochaufgelöste Messungen von Strömungen vorgenommen werden, aber üblicherweise sind Partikel für die Lichtstreuung einzubringen. In diesem Beitrag wird eine neuartige Methode vorgestellt, die keinerlei Streupartikel benötigt und eine gleichzeitige flächige Messung von Temperatur und Geschwindigkeit erlaubt. Die Methode basiert auf der spektralen Auswertung von gefilterter Rayleigh-Streuung. Durch die Verwendung einer kalibrierten analytischen Modellfunktion kann die Messunsicherheit des Systems reduziert werden.
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