Unraveling interactions between energy harvesting turbomachines and stratified environmental flows

Urgent modeling challenges are emerging as energy infrastructure rapidly expands in scale and complexity in response to soaring energy demand and climate change. This expansion is triggering new interactions between environmental flows and engineering systems. Energy infrastructure largely operates in stratified environmental flows such as atmospheric boundary layers and oceans/rivers. Beyond modeling these high Reynolds number, stratified, and turbulent environmental flows, there are also unresolved, multi-scale interactions between energy harvesting turbomachines and the environment that challenge predictive tools for devices such as wind and hydrokinetic turbines. We develop flow decompositions that separate the background environmental flow from the engineering system. First, we isolate turbine rotor aero/hydrodynamics from turbulent wakes. Using analysis of scale-resolving large eddy simulations and modeling that enforces integral conservation of mass, momentum, and energy, we develop analytical models of rotors in nonideal conditions that frequently occur in environmental flows including rotor-inflow misalignment and blockage. Then, we isolate turbulent wakes from the stratified, turbulent environment and we use large eddy simulations to identify the primary physical processes that control wake recovery and morphology. We develop a fast-running model of wake turbulence kinetic energy and we couple it with a wake momentum model based on the parabolized Reynolds Averaged Navier Stokes equations, accounting for stratified environmental turbulence. The fast-running wake model is coupled with the analytical rotor modeling and validated against large eddy simulations of turbulent wakes in the stratified atmospheric boundary layer.