Computational fluid dynamics simulations and validation of a novel constant volume combustion jet engine

The constant volume combustion thermodynamic cycle, or Humphrey Cycle, if made practical in a jet engine, can provide enormous benefits over the traditional jet engine cycle, the Brayton Cycle, which is a constant pressure cycle. These advantages include increased thermal efficiency, lower specific fuel consumption, and higher specific impulse. Other just as important benefits inherent in a constant volume device include simplicity of design, the ability to miniaturize the device because of the simplicity, low cost, damage tolerance, expendability, and a high thrust-to-weight ratio. This device has the potential to provide extremely high thrust in an austere, economical package. All of these attributes, when proven feasible, have the ability to provide a propulsion source for military and civilian applications alike, including applications in miniaturized unmanned aerial vehicles (UAVs). The purpose of this study was to computationally model, validate and understand the physics of a possible constant volume combustion jet engine, including the combustion and fluid mechanics of such a device. Specifically, the investigation included studying different engine geometries, valve designs and timing, various air inlet and fuel mixing schemes, operating frequencies, along with the effects of a convective air stream when a supporting vehicle is in flight at various airspeeds. This investigation sought to maximize thrust and minimize fuel consumption, and thus develop a jet engine with many possible future applications.