Research
Wind-turbine wake modeling with Atmospheric Boundary Layer
The long-term goal is to advance our understanding and capability to predict atmospheric boundary-layer turbulence and its interaction with wind turbines through synergy of controlled laboratory experiments, numerical modelling and field observation. We are interested in such scientific questions as: ) how to characterize the turbulence scale generated from wind farm wake-ABL interaction? 2) How far will the wind farm induced turbulence last and how much is the turbulence level increased compared to the ambient atmospheric boundary layer? 3) What are the effects of complex terrain (e.g., topography, high canopies, water surface and urban area), sharp transition of roughness/thermal conditions on wind turbine wakes? These question are essential to evaluate wind resources, predict wind farm energy production capability and assess wind farms impact on momentum, heat and moisture exchange between the land surface and atmosphere.
Wind Hazard Mitigation by Biomimicry and Bio-inspiration
The losses in billion-dollar disaster events in the U.S. are dominated by strong-wind-caused damage, destruction, and civil structure failure. Severe windstorms (such as hurricanes and tornadoes) and related water hazards have caused more than 90% of insured losses, and windstorms alone lead to 80% of losses. Post-disaster surveys have evidenced that failure of roofs and roof coverings accounts for the majority of the damage to low-rise buildings, including residential, commercial, and industrial buildings less than 18 meters. To enhance the wind resilience of low buildings, there is a critical need for effective mitigation strategies to reduce the damaging effects of roof suctions induced by flow separation and rooftop vortices.
The NSF CAREER project has set two scientific objectives: 1) to advance understanding of funda mental flow physics of rooftop vortices at high Reynolds number and 2) to create Nature-inspired flow control strategies to suppress rooftop vortices and thus mitigate adverse wind effects. In the five-year project, systematic wind-tunnel experiments will be conducted in the simulated hurricane-type winds at the Wall of Wind (WOW), Florida International University (FIU) facility through the NSF NHERI program. The ultimate goal is to enhance the wind resilience of low-rise buildings in extreme winds, such as hurricanes and tornadoes. The research is original, creative, and potentially transformative because the improved understanding of vortex dynamics governing the worst roof suction leads to better flow prediction models and enhanced wind design provisions. The bio-inspired innovation will amplify cost-effective, high-performance mitigation strategies that open opportunities and motivate radical thinking in broader engineering fields. The research significantly contributes to the design and reconstruction of wind-resilient low-rise buildings that will address the windstorm’s threats to life and property and remarkably reduce the destructive impact on our society.
Particle-laden Flows
Particle-laden flows pose great challenges to both scientists and engineers. For example, wind-blown sand flows are hard to model and predict, partly due to our incapability of measuring wind velocities in the dense saltation layer just above the ground. As an another example, when aircrafts operate in arid regions, dust particles of various sizes are entrained into engines and cause eroding blades and seals, seriously degrading turbine cooling performance. The goal is to quantify the turbulent flow and particle dynamics by developing new non-intrusive flow measurement techniques and data processing methods. High-speed photography combined with PIV will be applied to the particle-laden flow over a flat surface in a wind tunnel and unsteady flow in the conjunction of an engine air-particle separator for unmanned air vehicle applications.
