Visualization of pilot flame of an optically-accessible coaxially-staged aero-engine lean-burn fuel injector

[EN] The visualization of the pilot flame of a coaxially-staged aero-engine lean-burn fuel injector, not only downstream but also inside of the pilot nozzle, was successfully performed at realistic aero-engine conditions. Optical access toward the inside of the nozzle was achieved through the inner and outer shrouds, both of which were made of transparent quartz. The image distortion caused by complex contours of the two shrouds was corrected by a method based on optical ray tracing, which realized precise determination of spatial intensity distribution of optical signals. Line-of-sight OH chemiluminescence, cross-sectional OH-LIF, kerosene LIF and kerosene Mie scattering were employed as diagnostic tools. The effects of pilot local air-to-fuel ratio on spray flame structure were revealed, both inside and downstream of the pilot nozzle under stable combustions. As the pilot mixture got rich, the main reaction zone moved from inside of the pilot nozzle to the region near the injector lip downstream of the injector exit. The OH-LIF signal was detected near the central axis surrounded by the fuel spray. It was also observed near the back-step of the pilot nozzle for the rich cases. The experiments under combustion oscillation were also conducted and the correlation of phenomena inside and downstream of the pilot nozzle was captured. It was clarified that the reaction enhancement in the outer part of the lip vortex region was caused by the convection of rich mixture, which appeared near the pilot atomizer lip at 150~210deg earlier oscillation phase angle.Matsuura, K.; Uesaka, S.; Iwasaki, T.; Kurosawa, Y.; Yamada, H.; Yamamoto, T.; Hayashi, S. (2017). Visualization of pilot flame of an optically-accessible coaxially-staged aero-engine lean-burn fuel injector. En Ilass Europe. 28th european conference on Liquid Atomization and Spray Systems. Editorial Universitat Politècnica de València. 855-872. https://doi.org/10.4995/ILASS2017.2017.475285587

Plasma polymerization of silicon-containing monomers

Plasma depositions of ultra thin films from seven silicon-containing liquid monomers were investigated using a continuos wave (CW) plasma source. The deposition rate of plasma polymerized films were determined using a quartz crystal microbalance (QCM) technique while the film composition were determined spectroscopiclly using primarily X-ray photoelectron spectroscopy (XPS) and Fourier transform infrared method (FT-IR). The wettability of the plasma-polymerized films was also investigated by measuring the contact angles of water on the film surfaces. It was observed that the C=C absorption band was not present in these films. This observation is consistent with selective polymerization through the double bond. Oxygen was present in all samples investigated and this may be attributed to the quenching of radicals in the film by reactions with oxygen when exposed to atmosphere

Synthesis and dielectric measurements of lead and lead chloride phosphate glasses

A series of binary lead phosphate glasses (PbO)x(P2O5)1-x and lead chloride phosphate glasses, (PbCl2)x(P2O5)1-x have been successfully synthesized with x ranging from 0.1 to 0.5. The objective of the research is to determine the effect of mole fraction and temperature on dielectric properties of phosphate glasses. Frequency ranging from 10-2 to 106 Hz was chosen. The results obtained for the binary lead phosphate glasses showed that the addition of PbO or PbCl2 into the system will decrease the number of cross-links, hence increases the number of the non-bridging oxygen that will eventually weaken the structure bonds of the glasses. We can also say that the stiffness of the lead phosphate glass was decreasing as the mole fraction of PbO or PbCl2 increases. At room temperature, the value of the imaginary component of complex dielectric, ε’’ was seen to decrease with a slope of –1 as the frequency was increase whilst the real part, ε’ also decreased in parallel with ε’’ as the frequency was decreased but later flatten out towards high frequency. The trend was present in both the lead and lead chloride phosphate glasses. This low frequency dispersion could be due to the hopping of electrons or an ion in a potential double well arising at some localized defect. However as the temperature was increased, we found that the behavior of ε’’ was inversely proportional to frequency while ε’ remained relatively constant at all frequency measured. This response is usually associated with direct current conduction in the material in the relevant frequency range

The Erotic and the Vulgar: Visual Culture and Organized Labor's Critique of U.S. Hegemony in Occupied Japan

This essay engages the colonial legacy of postwar Japan by arguing that the political cartoons produced as part of the postwar Japanese labor movement’s critique of U.S. cultural hegemony illustrate how gendered discourses underpinned, and sometimes undermined, the ideologies formally represented by visual artists and the organizations that funded them. A significant component of organized labor’s propaganda rested on a corpus of visual media that depicted women as icons of Japanese national culture. Japan’s most militant labor unions were propagating anti-imperialist discourses that invoked an engendered/endangered nation that accentuated the importance of union roles for men by subordinating, then eliminating, union roles for women

Active control of combustion oscillations in a lean premixed combustor by secondary fuel injection coupling with chemiluminescence imaging technique

An active control of combustion driven oscillations occurring in a lean premixed model combustor is demonstrated by means of a secondary fuel injection. An unstable condition, which leads to self-excited pressure oscillations beyond 170 dB, is chosen as control target. Keeping the inlet air temperature, the air mass flow rate and the overall equivalence ratio, respectively at 700 K, 78 g/s and 0.50, different secondary fuel injection strategies are examined. First, a series of experiments of steady secondary fuel injection is performed using five types of injectors, with secondary fuel percentage (SFP) varying from 2% to 10%. Effects of the angle, location and amount of injection on pressure levels are investigated. A favorable injector is selected from a point of view of control effectiveness, which is evaluated by the reduction in the peak pressure. The degree of phase coupling between pressure and heat-release rate is visualized by a phase-locked chemiluminescence imaging technique. This information is used to detect local sources of instability. To further improve control effectiveness, a closed-loop control, which was designed by the mixed H2/H∞ control algorithm, is applied with the selected injector. The closed-loop control with 2.5% SFP performs peak pressure reduction of 27.7 dB, which is almost 10 dB larger than that of the steady injection method. An explanation for the difference in the reduction levels is given by showing pressure-chemiluminescence correlation maps. On the other hand, little difference exists between the NOx emissions of the steady injection and the closed-loop control. An obvious effectiveness of the closed-loop control is confirmed without losing the low NOx capability