A Combined Experimental and Computational Study of the LAPCAT II Supersonic Combustor

Axel Vincent-Randonnier, Vladimir Sabelnikov, A Ristori, Niklas Zettervall, Christer Fureby
2018 22nd AIAA International Space Planes and Hypersonics Systems and Technologies Conference   unpublished
Dual-mode ramjet propulsion systems are suggested for the next generation high-speed flight vehicles. Here, we combine experimental measurements of high-speed (subsonic and supersonic) combustion at different operating conditions in the LAPCAT-II dual-mode ramjet combustor with Large Eddy Simulations (LES) using finite rate chemistry models and new skeletal H 2 -air combustion chemistry. The LAPCAT II combustor consists of four sections, and experiments have been performed for wall injection of
more » ... H 2 in a Ma 2.0 vitiated airflow for total pressures and temperatures of p 0 =0.40 MPa, 1414 K<T 0 <1707 K, and a fixed equivalence ratio of φ=0.15. For this p 0 the combustor is over-expanded, and the transition from supersonic to subsonic flow occurs at the start of the fourth combustor section. The flow and combustion diagnostics include measurements of p 0 and T 0 upstream of the combustor, wall-pressure profiles and Schlieren and OH* chemiluminescence imaging. The computational set-up consists of the full combustor, from the nozzle to the dump-tank. The computational model is composed of a compressible finite rate chemistry LES model, using the mixed subgrid flow model and the Partially Stirred Reactor (PaSR) combustion model, together with a new 22 step H 2 -air reaction mechanism. Qualitative as well as quantitative comparisons between experiments and simulations show reasonable agreement, but also reveal a high sensitivity of both the LES predictions and the experiments to T 0 . The LES results are further used to describe the underlying mechanisms of flow, wall-injection, mixing, self-ignition and turbulent combustion, and how these interrelated processes are modified by increasing the total temperature under otherwise identical conditions.
doi:10.2514/6.2018-5208 fatcat:kyadv2mbm5fqjkieszvl67e65q