Many critical engineering applications such as jet engines, rocket engines, gas pipelines, wind tunnels, etc., rely on internal compressible flows. While designing these systems engineers try to achieve their goals with minimal losses from compressible waves and friction. In this course we will look into various aspects of internal compressible flows. We will begin with one-dimensional flows with heat addition and friction. Then we will analyze quasi-1D flows and apply the knowledge to the analysis of converging–diverging nozzles, diffusers and wind tunnels. Lastly, we will discuss the method of characteristics and use it in the design of supersonic nozzles.