PARP1 is required for adhesion molecule expression in atherogenesis

Aims Atherosclerosis is the leading cause of death in Western societies and a chronic inflammatory disease. However, the key mediators linking recruitment of inflammatory cells to atherogenesis remain poorly defined. Poly(ADP-ribose) polymerase 1 (PARP1) is a nuclear enzyme, which plays a role in acute inflammatory diseases. Methods and results In order to test the role of PARP in atherogenesis, we applied chronic pharmacological PARP inhibition or genetic PARP1 deletion in atherosclerosis-prone apolipoprotein E-deficient mice and measured plaque formation, adhesion molecules, and features of plaque vulnerability. After 12 weeks of high-cholesterol diet, plaque formation in male apolipoprotein E-deficient mice was decreased by chronic inhibition of enzymatic PARP activity or genetic deletion of PARP1 by 46 or 51%, respectively (P < 0.05, n ≥ 9). PARP inhibition or PARP1 deletion reduced PARP activity and diminished expression of inducible nitric oxide synthase, vascular cell adhesion molecule-1, and P- and E-selectin. Furthermore, chronic PARP inhibition reduced plaque macrophage (CD68) and T-cell infiltration (CD3), increased fibrous cap thickness, and decreased necrotic core size and cell death (P < 0.05, n ≥ 6). Conclusion Our data provide pharmacological and genetic evidence that endogenous PARP1 is required for atherogenesis in vivo by increasing adhesion molecules with endothelial activation, enhancing inflammation, and inducing features of plaque vulnerability. Thus, inhibition of PARP1 may represent a promising therapeutic target in atherosclerosi

A test rig for investigations of gas turbine combustor cooling concepts under realistic operating conditions

In the current paper, a new test rig for the characterization of advanced combustor cooling concepts for gas turbine combustors is presented. The test rig is designed to allow investigations at elevated pressures and temperatures representing realistic operating conditions of future lean low emission combustors. The features and capabilities of the test rig in comparison to existing rigs are described. The properties of the hot gas flow are measured in order to provide the necessary data for a detailed analysis of the measured cooling effectivity of combustor wall test samples. Results of the characterization of the velocity and temperature distribution in the hot gas flow at the leading edge of the test sample at pressures up to p<=10 bar and near wall hot gas temperatures up to TF<= 1800 K are presented

A Test Rig for Investigations of Gas Turbine Combustor Cooling Concepts under Realistic Operating Conditions

In this paper a new test rig for the characterization of advanced combustor cooling concepts for gas turbine combustors is introduced. The test rig is designed to allow investigations at realistic operating conditions of future lean combustors at elevated pressures and temperatures. The features and capabilities of the test rig in comparison to existing rigs are described. The properties of the hot gas flow are measured in order to provide the necessary data for an detailed analysis of the measured cooling efficiency of combustor wall test samples. Results of the characterization of the velocity and temperature distribution in the hot gas flow at the leading edge of the test sample at pressures up to p=10bar and global flame temperatures up to T=2000K are presented

Validation methodology for the development of low emission fuel injectors for aero-engines

This contribution describes a newly derived devel-opment chain for the early design and validation phases of lean burning injectors allowing a faster and cheaper design process. It comprises an initial con-cept definition, design optimizations based on CFD and a design validation by qualitative fuel flow tests, followed by the application of laser diagnostic meth-ods. Finally, emission and operability characteristics are determined at real operating conditions. The comprehensiveness of the applied development chain has been proved to significantly reduce NOx emissions of the lean burners and to generate vali-dated design rules for the fuel injectors analyzed in this study

Characterization of Advanced Combustor Cooling Concepts under Realistic Operating Conditions

For future low emission aero engine combustors a significant reduction of cooling air consumption is required. Quantitative data of the performance of advanced cooling concepts in a realistic environment in addition to existing data from scaled isothermal investigations is needed by combustor designers for further improvements. The effect of the cooling air properties on the cooling effectiveness of different advanced cooling concepts at realistic operating conditions is analyzed. Adapting of the measuring techniques and correction of the exhaust gas radiation will be especially addressed. An introduction into basic cooling design considerations is included

Stabilität intern gestufter Magermodule, Kühlungseigenschaften fortschrittlicher Brennkammerschindeln

Verschiedene Varianten eines intern gestuften Magermoduls wurden u.a. unter Einsatz Laser-optischer Verfahren untersucht im Hinblick auf Verteilung des flüssigen und gasförmigen Kraftstoffs, Zonen der Wärmefreisetzung, der Geschwindigkeitsverteilung des Strömungsfeldes sowie Tropfen-Größen und –Geschwindigkeiten des Kerosin-Sprays. Dabei wurde die Auswirkungen unterschiedlicher geometrischer Konfigurationen zur Strömungsführung sowie verschiedener Stufungsverhältnisse auf Stabilität und Pilotierungswirkung sowie das Ausbrandverhalten des Pilotbrenners charakterisiert. Weitere Experimente dienten der Untersuchung des Kraftstoff-Systems im Hinblick auf Umfangshomogenität. Die Untersuchungen an verschiedenen Brennkammer-Schindeln zeigten den Einfluss der Bohrungen zur Effusionskühlung sowie der Betriebsparameter. Flachere Bohrungswinkel verbessern die Kühleffektivität; ferner wurden der Einfluss von Heissgasdruck und –Temperatur, Kühllufttemperatur sowie Druckverlust aufgezeigt

Optical Measurements of the Reacting Two-Phase Flow in a Realistic Gas Turbine Combustor at Elevated Pressures

A rectangular sector of a realistic axially staged gas turbine combustor of Rolls-Royce Deutschland was operated at elevated pressures. Optical measurements of the reacting two-phase flow were performed using Phase Doppler Anemometry (PDA) and two planar light sheet techniques, laser induced fluorescence (LIF) and Mie scattering. The constraints, e.g. limited optical access, combustor with several injectors in line and strong soot luminescence, affecting the optical set-up for PDA measurements are discussed. The PDA measurements were conducted at a combustor inlet pressure of p = 6 bar. With an estimated error in the size measurement of up to = 10 % caused by the change of the refractive index, it was still possible to obtain quantitative results of the mean diameter. The error of the liquid volume concentration is higher and difficult to assess. Images of the planar Mie scattering are used as a consistency check of the PDA data. The light sheet techniques deliver supplementary information. Imaging of kerosene LIF of an isothermal spray at atmospheric pressure was used to calculate the liquid volume concentration. A comparison with results from PDA measurements revealed a good agreement. Under reacting conditions kerosene LIF was limited to qualitative information on the distribution of liquid and vaporized fuel mainly because of the temperature dependency of the fluorescence quantum yield. At higher pressure the applicability of LIF was limited by the absorption of the UV laser light in the dense spray. Imaging of the planar Mie scattered light was possible at combustor inlet pressures up to p = 20 bar, giving qualitative information on the distribution of the liquid fuel

SDLA/DLAS measurements on the APZ combustor at DLR

This presentation describes measurements performed using an infrared diode laser absorption spectrometer (DLAS) in an Atmospheric Primary Combustor (APZ) at DLR Cologne. This work was performed in the frame of the European Project MENELAS “Minority effluent measurements of aircraft Engine emissions by infrared Laser Spectroscopy” (5th Framework). A description of the burner and the optical accessible combustor are given. The combustor was operated at atmospheric pressure and air preheat temperature and equivalence ratio were set to provide a temperature, velocity and species distribution typical for future low emission combustors. Spatially resolved measurements of the gas velocity, temperature and composition (O2, CO, CO2, NOx and unburned hydrocarbons) in the reacting burner flow field and at the combustor exit are presented. The measurements were conducted with generally accepted standard techniques using Laser Doppler Anemometry (non-intrusive), thermocouple probes and conventional exhaust gas analysis respectively. The measured results act as a benchmark and reference for the SDLA/DLAS measuring campaign. The DLAS instrument was used primarily on the CO molecule to acquire series of measurements on inside and outside combustor(5 mm scanning horizontal and vertical). Measurements were performed with a repetition rate of 20kHz to cope with the temporal fluctuations of the combustor. Data reduction allowed deriving pressure, temperature and CO concentration on the absorption path. The given values are hence averaged values but there were some attempts to compare with the results of the classical probing. Spatial deconvolution is yet to be performed for a more thorough exploitation and comparison. The CO2 molecule was also probed but wavelength and envelope calibration are more difficult because of inadequate spectral filtering and ambient CO2 presence giving intense background absorption lines. Some H2O lines were also found present in the spectra which are still being data reduced. There was also trials to probe the NO molecule but the allowed NO lines with the present laser diodes did not have sufficient sensitivity to probe the weak NO concentration present in/outside the combustor. This first attempt of DLAS in an APZ combustor proved that infrared absorption spectroscopy is possible in such a media. Improvements in data acquisition, spectral filtering and data reduction are now necessary for a better exploitation of this technique to perform measurements of pressure, temperature and concentrations of CO, CO2, NO and H2O in such combustion devices

In situ measurement and validation of gaseous species concentrations of a gas turbine model combustor by tunable diode laser absorption spectroscopy

In the framework of a European research project, ONERA and DLR have studied the applicability of infrared laser techniques to gas turbine combustor measurements. The final goal is to replace gas analysis with probe measurements by optical techniques fulfilling the ICAO standards for engine emission measurements. Infrared laser absorption spectroscopy has the potential for fast, high spatial resolution measurements of combustion species with rugged equipment and therefore might contribute to the reduction of combustor development time and cost. Furthermore, the measurement of minor species in the combustor could help the understanding of the combustion process in the gas turbine. The tunable diode laser absorption technique of ONERA was used to probe CO, CO2, NO and H2O. The apparatus and measurement procedure including the upgrades for the combustor measurements are described. Successful measurements were achieved with CO inside and outside of the combustor. The reactive flow field of the model combustor was characterized with conventional measurement techniques. The CO measurements by TDLAS were compared with probe measurements that could be weighted by temperature and velocity measurements. Furthermore, temperature information was derived from the Laser measurements. The results are compared and further improvements are discussed