Based on the flow reactor with optical accesses, autoignition characteristics of the n-decane transient injection in non-vitiated air crossflow was studied at various conditions relevant to gas turbine combustor: the air crossflow pressure of 1.7 MPa, the crossflow temperatures of 750 K and 1000 K, and the jet-to-crossflow momentum ratios of 55 and 72, and Weber number of 250. Photoelectric sensor was installed at the exit of the nozzle to record the time of fuel injection; Photomultiplier equipped with CH\* chemiluminescence filter was installed in the end of the flow reactor to detect the time of the autoignition. the autoignition delay time was defined as the time interval between the fuel injection into the flow reactor and the radical emission from ignition kernel. Statistical distributions (probability density) of random ignition delays of non-premixed spray with adequate convergence were estimated based on histograms, and the dependences of the distributions on reactor pressure, temperature and jet-to-crossflow momentum ratio were parametric studied. A total of 100 experiments were conducted under the same operating conditions to acquire the probability distribution. The results confirm the existence of the stochastic behavior of n-decane spray autoignition in the crossflow, and the distributions show good agreement with the theoretical Gaussian functions, which were determined by sample mean and standard deviation of ignition delay data. By the results of high-speed camera, the study proved that due to instability nature of fuel primary breakup and stochastic atomization process, the formation conditions of the autoignition kernel are stochastic, which leads to the probability distribution of ADT. The probability distribution becomes more concentrated with the increase of temperature and momentum ratio. And finally, the correlations for the mean and standard deviation of the ignition delay, covered by the aforementioned operating conditions, were developed as a function of the above parameters.


Experimental Study on Random Autoignition of N-Decane Spray in Crossflow at Evaluated Pressure

Division / Sponsor:
International Gas Turbine Institute (IGTI)

Paper Proceedings: https://asmedigitalcollection.asme.org/GT/GT2020/volume/84058

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