Jet engines, scramjets, rockets, and solar energy receivers have been the focus of a sequence of computational projects at Stanford University. Featuring a combination of computer science and multi-physics turbulence simulations, the research is funded by US Department of Energy within the Advanced Simulation and Computing (ASC) Program. A common theme of the applications above is the coupled nature of the physical processes involving turbulent transport, combustion, radiation, compressible fluid mechanics, multiphase flow phenomena, etc. The research portfolio includes not only the development of the engineering models and software tools required for the simulations, but also innovations in high performance computing and machine learning aimed at enhancing simulation speed. To build confidence and improve the prediction accuracy of such simulations, the impact of uncertainties on the quantities of interest must also be measured. The talk will focus on the numerical simulations of particle laden turbulence subject to radiation and the laser-based rocket ignition and will illustrate the main challenges and innovations introduced.