Supersonic Combustion Models Application in Advanced Propulsion Concepts

Hydrogen/Air Supersonic Combustion Modelling and Validation for Scramjet Applications

“…The optimal scheme arises as a suitable trade-off between the accuracy, required for a reliable description of ignition and combustion phenomena and the computational cost, associated with the available calculation speed and memory storage capacity. For this purpose, a preliminary zero-dimensional kinetic analysis of hydrogen/air combustion at the most relevant operative conditions for this application was performed using seven kinetic mechanisms of hydrogen ignition and combustion, selected as the most suitable ones based on the author's experience and the literature review by Gerlinger et al [2], Olm and co-workers [3] and Hu et al [4] i.e., both the detailed [5] and reduced version of the Jachimowski mechanism [6][7], CRECK -2012 [8], Kéromnès -2013 [9] and Z22 --2018 [10]. Moreover, further two full mechanisms i.e., Aramco-II [11][12][13] and GRI-Mech 3.0 [14], conceived respectively for large hydrocarbons and natural gas modelling, but in any case, endowed with a well-established H2/O2 submechanism, were investigated and used as references.…”

“…In addition, full 3D CFD analyses were carried out in order to numerically rebuild the achievements of a specifically conducted experimental testing campaign and compare laser absorbance measurements to computational predictions and evaluate the accuracy and reliability of such chemical/physical models. In particular, a reduced version of the Jachimowski scheme [6][7] was compared to the mechanism developed by Zettervall.…”

Specific features of ignition and flameholding of hydrocarbon fuels in high-speed flow

“…The di©culties of the use of hydrocarbon fuels as compared with gaseous systems are caused by the longer residence times required for vaporization, mixing, and completion of chemical reactions [57]. In general, the key elements for successful operation ¦eld and to determine the e¨ects of di¨erent fuel injection schemes on the overall scramjet combustion e©ciency [27,31]. Di¨erent arrangements were compared in terms of species mixing e©ciency and overall combustion optimization.…”

“…In some cases, the location of fuel injectors and the angle of injector ori¦ces are varied to determine the optimum injection scheme. All combustor con¦gurations include a backwardfacing step, cavity, or struts [32] and their combinations [31] to provide §ame-holding and stabilization in the combustor; for example, mixing e©ciencies are predicted for 10 di¨erent injection schemes. The comparative results indicate that the fuel injection con¦guration with opposing injector pairs located in the cavity, on the step, and the ramp are the most e©cient, resulting in 73 percent combustion e©ciency [30].…”

“…In spite of numerous studies of combustion chambers with supersonic §ow, up to now, there are no acceptable methods of calculation, which would allow predicting reliably the mechanism and conditions of ignition and combustion stabilization. As a rule, the calculation methods are based on empirical or semiempirical relations, which use the experimental results [7,31,34]. Considering the complexity of the phenomenon and multiparametric character of the problem, these methods have limited applicability and do not always provide satisfactory results.…”