Das Projekt "Vorhaben 2.3.4.A" wird vom Umweltbundesamt gefördert und von Technische Universität Darmstadt, Fachgebiet Reaktive Strömungen und Messtechnik durchgeführt. Die TU Darmstadt entwickelt ein Laser-Hygrometer auf Basis der Tunable Diode Laser Absorption Spectroscopy (direkt-TDLAS) zur Zwei-Linien-Thermometrie an Hochdruck-Brennkammern. In einem zweiten Schritt wird planare laserinduzierte Fluoreszenz am OH-Radikal zur zeitlich hochaufgelösten Diagnostik in der Hauptreaktionszone einer Gasturbinenbrennkammer angewendet. Zunächst wird eine Selektion geeigneter Absorptionslinien und die Neubestimmung deren spektroskopischer Liniendaten durchgeführt. An die Charakterisierung der Laser schließt sich die Konzeption des Spektrometers und die Erprobung an einem Modellbrenner der RSM-Hochdruckkammer an. Schließlich wird das Spektrometer zur Gastemperaturmessung an der Versuchsbrennkammer HBK2(DLR Köln) eingesetzt. Des Weiteren wird die Eignung der Nutzung des an den Brennkammerwänden entstehenden Streulichts untersucht. Im Bereich der Highspeed - OH- PLIF wird die Einkopplung der UV-Laserstrahlung in die Brennkammer realisiert. Darauffolgend erfolgt die PLIF Messung am SCARLET Rig (HBK3) an der DLR Köln.
Das Projekt "Metrology for pressure, temperature, humidity and airspeed in the atmosphere: Upper air measurements: sensors and techniques" wird vom Umweltbundesamt gefördert und von Physikalisch-Technische Bundesanstalt durchgeführt. Water vapour is the most important greenhouse gas in the earths atmosphere and a key component for physical and chemical atmospheric effects. Measurement of atmospheric humidity (in terms of volume concentration of water, or relative humidity) is absolutely essential to understand atmospheric radiation transport, atmospheric chemistry, cloud formation or precipitation and thus also for advanced climate models needed to simulate climate change effects. One of the big challenges of water vapour measurements is the wide dynamic range of the water content in the atmosphere covering nearly five orders of magnitude. While under standard ambient conditions (20 C, 1013 hPa) the average volume fraction of water in temperate climate zones is in the range of 1 to 2 percent and about 5 percent in the tropic regions, in higher elevations humidity decreases as temperature decreases and reaches its minimum (of only a few ppm) near the tropopause in a heights between 8 and 15 km depending in latitude. This wide dynamic range with a factor of more than 10 000 is a real challenge for humidity sensors of any type. Numerous humidity sensors have been developed for atmospheric measurements on platforms from ground to airborne like planes or balloons, as well as various more or less home made protocols for their calibration. However, the very few intercomparisons for field instruments to validate their performance revealed significant uncertainties of 10Prozent and beyond even in between the best, well established instruments and a severe lack of consistent calibration protocols not to mention traceability to national humidity standards. In order to provide consistent atmospheric humidity data especially in field situations improved calibration instruments and protocols (preferably traceable to national standards) need to be developed and established in the community and a new generation of traceable field humidity sensors is needed.
Das Projekt "Luftfahrzeuggestuetzte Messungen von Aerosolen und verbundeen Spurengase" wird vom Umweltbundesamt gefördert und von Max-Planck-Institut für Kernphysik durchgeführt. AAGRA will carry out coordinated balloon-borne measurements of aerosols and related trace gases in the winter polar stratosphere, including measurements of: aerosol size, aerosol number densities, aerosol composition (H2SO4, SO2, HNO3, NH3), condensable gases (H2SO4, HNO3, H2O), optical properties of aerosols (depolarization, index of refraction, shape), aerosol back scattering ratio. The AARGA measurements will, within the framework of SESAME, be closely coordinated with air-borne and ground-based measurements of stratospheric species. In particular, close coordination with ground-based LIDAR measurements will be possible. Furthermore, AARGA measurements will be coordinated with satellite observations, particularly of aerosol properties. Measurements of the properties of aerosols (composition, size, number densities, optical properties) condensed trace gases (H2SO4, HNO3, H2O), and related trace gases (HNO3, HCI), affected by aerosol-catalyzed reactions will be performed using various instruments and methods. A BAMAS (Balloon-borne Mass Spectrometer) - BAMAS-CIMS (Chemical Ionization Mass Spectrometry): Mass spectrometer measurements of trace gases. BAMAS-VACA (Volatile Aerosol Composition Analyses): Mass spectrometer measurements of compounds of volatile aerosols. BAMAS-IOMAS (Ion Mass Spectrometer): Mass spectrometer measurements of ambient ions. Concentration of gaseous H2SO4 can be inferred from ion composition measurements. B. ELHYSA (Etude de I'Hygrometrie Stratospherique et des Aerosols). ELHYSA is a combined water vapour and aerosol instrument. H2O is measured by a frost-point hygrometer. Particle and concentration of aerosols are measured by a laser diode particle counter.