This paper describes a numerical study of the laser-pulse ignition sequence occurring in the combustion chamber of the M3 facility at DLR-Lampoldshausen. Our methodological approach relies on a variable fidelity modeling of the main phenomena of interest. In-house tools are fed with spatially homogeneous, isochoric, forced ignition problems, to derive a simplified methane/oxygen kinetic mechanism. The kernel formation after the laser pulse energy deposition is firstly studied in a one-dimensional framework, so as to test the simplified kinetic mechanism ability to reproduce the ignition behavior. The kernel initiation is also simulated in a two-dimensional mixing layer, to assess the ability of the simplified mechanism to accurately describe both the kernel initiation and its spatial propagation. Both the one- and two-dimensional simulations are carried out by means of a wavelet-based CFD library. Next, a lumped analysis of the events connected with the ignition sequence is carried out by adopting a well-stirred reactor model for the M3 chamber. The numerical results are compared to experiments carried out by DLR-Lampoldshausen, and the discrepancies are discussed. Finally, the whole M3 geometry and ignition sequence are simulated by means of an Unsteady Reynolds-averaged Navier-Stokes (URANS) model under the axi-symmetric flow approximation. The URANS results are compared with the experimental data, showing that URANS axi-symmetric calculation are able to provide a rather accurate picture of the ignition transients. Nevertheless, some issues on the quantitative accuracy of the URANS predictions are found and discussed in detail.
Numerical analysis of laser-pulse transient ignition of oxygen/methane mixtures in rocket-like combustion chamber
Martelli, E.;
2019
Abstract
This paper describes a numerical study of the laser-pulse ignition sequence occurring in the combustion chamber of the M3 facility at DLR-Lampoldshausen. Our methodological approach relies on a variable fidelity modeling of the main phenomena of interest. In-house tools are fed with spatially homogeneous, isochoric, forced ignition problems, to derive a simplified methane/oxygen kinetic mechanism. The kernel formation after the laser pulse energy deposition is firstly studied in a one-dimensional framework, so as to test the simplified kinetic mechanism ability to reproduce the ignition behavior. The kernel initiation is also simulated in a two-dimensional mixing layer, to assess the ability of the simplified mechanism to accurately describe both the kernel initiation and its spatial propagation. Both the one- and two-dimensional simulations are carried out by means of a wavelet-based CFD library. Next, a lumped analysis of the events connected with the ignition sequence is carried out by adopting a well-stirred reactor model for the M3 chamber. The numerical results are compared to experiments carried out by DLR-Lampoldshausen, and the discrepancies are discussed. Finally, the whole M3 geometry and ignition sequence are simulated by means of an Unsteady Reynolds-averaged Navier-Stokes (URANS) model under the axi-symmetric flow approximation. The URANS results are compared with the experimental data, showing that URANS axi-symmetric calculation are able to provide a rather accurate picture of the ignition transients. Nevertheless, some issues on the quantitative accuracy of the URANS predictions are found and discussed in detail.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.