Design of the TUMBLE chamber’s turbulence generator • The chamber TUMBLE studied by Le Dortz [2] was modified in order to be able to control the turbulence intensities and the turbulent length scales. • Based on literature review [3], a set of 3 perforated plates were chosen. Introduction IWPD and ICVDCW 2022 August 15-19, 2022 Berlin, Germany Experimental characterization of ignition events in CVC like conditions M. C. de Jesus Vieira, J. Sotton, M. Bellenoue, C. Strozzi maria-clara.de-jesus-vieira@ensma.fr Institut Pprime, CNRS, Université de Poitiers, ISAE-ENSMA, F-86962 Futuroscope Chasseneuil, France Concepts and project overview Concepts and project overview Conclusion and perspectives • Since early development, the thermodynamic cycle used in gas turbines has undergone little change. Over the last decades, an effort has been put into increasing efficiency by reducing losses and raising the overall pressure ratio and peak temperature. One of the most promising new types of cycles is the case where a pressure rise across the combustion process is allowed (CVC). In this case, an ignition in each cycle will be considered and also diluted mixtures with high mean velocities and turbulent flows. The main objective of this work is to experimentally investigate the different phenomena involved in the ignition stage in a CVC application, such as the effect of the dilution by a residual burned gas (RBG), the turbulence intensity, and turbulence length scales. • For this purpose, a lab-scale facility was developed to generate turbulent flow and to allow electrical energy measurements. The setup will allow a well-controlled flow, with the possibility to vary the mean velocity and turbulent scales. The ignition system's energy and power effects on the ignition process will be studied. Definition of RBG composition • In order to define the composition of the synthetic RBG, the main flame properties were analyzed (𝑇𝑏, 𝑆𝐿, 𝛿) • Mixture: Propane/air - 𝜙= 0,7, P = 1 bar and 2 bar and ambient temperature. • The calculations were made using Cantera with the San Diego chemical mechanism [1]. • The mixture chosen was so that the heat release from the RBG produced would be the same. • Synthetic RBG dilution mixture chosen: 5% He + 95% N2 (without H2O). • A mixture of 5% He + 95% N2 is adequate and behaves as a residual burned gas. • The perforated plate design describes the desired turbulence intensity profile. • Optical diagnostics will be made to characterize the turbulence and ignition in the chamber. • MIE [1] measurements will be performed for a propane/air mixture with synthetic RBG dilution. with the new turbulence generator. • For spark duration lower than 0.4 ms, a smaller calorimetry chamber could be used. References [1] Chemical - Kinetic Mechanisms for Combustion Applications, San Diego Mechanism web page, Mechanical and Aerospace Engineering (Combustion Research), University of California at San Diego. http://combustion.ucsd.edu [2] R. le Dortz, “Détermination des caractéristiques fondamentales de combustion de pré-mélange air-kérosène, de l’allumage à la vitesse de flamme : représentativité de surrogates mono et multi-composants.” Thesis. Ecole nationale supérieure de mécanique et d'aérotechnique. [3] N. Mazellier, L. Danaila, and B. Renou, “Multi-scale energy injection: A new tool to generate intense homogeneous and isotropic turbulence for premixed combustion,” Journal of Turbulence, vol. 11, pp. 1–30, 2010, doi: 10.1080/14685248.2010.519708. [4] C. C. Huang, S. S. Shy, C. C. Liu, and Y. Y. Yan, "A transition on minimum ignition energy for lean turbulent methane combustion in flamelet and distributed regimes," Proceedings of the Combustion Institute, vol. 31 I, no. 1, pp. 1401–1409, 2007, doi: 10.1016/j.proci.2006.08.024. [5] C. J. BENITO PAREJO. “Experimental Characterization of Electrical Discharges and Formation of the Ignition Kernel. Application to the Study of Performances of Aeronautical Igniters”. 2019. Thesis. Ecole n