We have used the pressure-sensitive paint (PSP) intensity and lifetime methods for basic research and PSP measurements in wind tunnels and turbomachines, to investigate and understand the qualitative and quantitative aerodynamic measurements mainly in transonic flow. We performed a number of investigations in different speed ranges from transonic to low-speed flow and compared them with conventional techniques like pressure taps and light sheets. The influence of errors was checked and a comparison with numerical methods performed. Various models were investigated, from the basic configuration of a double-delta-wing up to a complex Airbus A340 half model and oscillating turbine blades. Finally, two excellent PSP systems are now available to perform precise measurements and support the theory using these techniques.

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Delta wing 0.17 0.3 Car-model 0.12 0.12 NACA 0012 0.30 1 DLR-Gottingen, GERMANY Sullivan [7] I Jet interaction I ABSTRACT 3Pressure field measurements on a wing profile are conducted to evaluate the accuracy of a measurement system using the so called "binary" or "two-color''Pressure Sensitive Paint (PSP) for low-speed (40-60 &sec) environments. A part of the wing surface was coated with a binary paint. Two different light sources, a high pressure Xenon-flash lamp and a nitrogen laser were used for the excitation of the paint. The resulting fluorescence fields were acquired by a 16-bit CCD slowscan camera. In front of this camera two different optical devices, a filter-shifting system or alternative a beamsplitting system, each of them were equipped with appropriate optical filters to separate the two different spectral emission wavelen,g of the paint, were used. Results shows that this optical pressure measurement system is able to resolve the small pressure changes on the model surface. Due to model movement and model deformation in between the image acquisition of the "wind-off' and "wind-on" images the necessity to use a binary paint for precise pressure measurements is clearly visible. These PSP-System working with binary paint can achieve pressure resolution in the region of 1 mbar. NOMENCLATURE= luminescence intensity = quenching constant = partial pressure of oxygen = local static pressure = calibration coefficients of a paint = response time = thickness of the binder layer = diffusion coefficient of oxygen = aspect ratio SUBSCRIPTS 0 ref = reference condition = absence of oxygen (vacuum conditions)

With a first application of semiconductor lasers to absorption measurements of seeded atomic Rb in high-enthalpy flow fields, a diagnostic technique for time-resolved determination of flow velocity and gas temperature with a line-shape analysis was developed. In our measurements a GaAlAs diode laser was used to scan repetitively at 15 kHz over 1.3 cm(-1) across the D(2) resonance transition (5S(1/2) ? 5P(3/2), 780.2 nm) of seeded atomic Rb to obtain multiple absorption line shapes. The time-dependent signal contains highly resolved spectral line-shape information, which we interpret by fitting the spectrally resolved line shapes to Voigt profiles. Kinetic temperatures in the range 900-1400 K and gas velocities in the range 3900-6200 ms(-1) were obtained from the Doppler-broadened component of the line shape and from the Doppler shift, respectively, of the absorption frequency.

Pressure Sensitive Paint (PSP) provides a pressure map on the whole surface of a wind tunnel model without transducers and tubing. In principle there are two different ways to gather experimental data -by using the fluorescent decay time of excited luminophore molecules (lifetime method) or by detecting its integrated fluorescent emission (intensity method). During the last five years PSP measurements utilizing the intensity of the luminescence are performed at DLR with pyren-based paints. This paint is characterized by its low temperature sensitivity and high quantum efficiency -due to these qualities the lifetime technique is also developed for this paint type. PSP measurements utilizing the lifetime of the luminescence are independent to particles in the flow (dust, oil, condensed water, etc.), changing in density, light source instabilities and light reflection and less sensitive to the model movements because there is no need for a reference image. The short luminescence decay time of pyren in the order of 50 ns gives the possibility to investigate fast flow processes (pressure measurements on helicopter blades, propellers, turbines, etc.). Using the same paint for the intensity as well as the lifetime technique a simultaneously application will complete the existing PSP system.