Current Research Projects

Electric Powered Aircraft and Aerodynamics of Distributed Propulsion

Battery technology and autonomous control have advanced to a point where electric-powered passenger aircraft, with approximately 2–4 passengers (i.e., air taxis), are becoming feasible. Electric motors scale very differently than gas turbine engines, and have very different power curves, allowing for things like short or even vertical takeoff and landing, and distributed propulsion (many small propellers instead of a few big propellers). Distributed propulsion systems can allow for greater redundancy, control authority, performance, and maneuverability. However, operating many rotors in close proximity, or spread around the vehicle, creates strong aerodynamic interactions that are not well understood. We are developing an analysis and design methodology based on a vortex particle method to more accurately capture wake interactions and perform novel design studies for air taxi applications. Using electric motors affects all systems and thus completely changes the way the aircraft is designed. We are exploring optimization-driven design studies to improve electric powered aircraft.

Wind Farm Optimization

The wakes behind wind turbines reduce the potential power production of other turbines in the farm. This problem is further complicated because the wind speed and direction change frequently both temporally and spatially. Layout design seeks to reduce wake interactions through optimization. This is a particularly challenging optimization problem. The design space is filled with local optima and the problems may have hundreds of design variables and thousands of constraints. We have been developing wake models that enable efficient optimization procedures and have been exploring design studies of large wind farms, including simultaneous design of the layout, the turbines themselves, and their orientations.

High Altitude Long Endurance Aircraft

Aircraft can be used to provide internet in developing areas of the world at a lower cost than deploying new satellites. The challenge is that such aircraft need to be persistent (i.e., stay airborne for months at a time). This drives the aircraft design to very large wing spans in order to reduce lift-dependent drag, and to very high altitudes where wind speeds are low. Wings that are simultaneously lightweight and large in span, are highly flexible and create unique unsteady aerodynamic and structural dynamic challenges. We are working on high-fidelity approaches to analyze and design such configurations. These challenges are applicable not only to flexible aircraft wings, but also to wind turbine blades and other aeroelastic applications. The performance requirements of HALE aircraft necessitate a multidisciplinary design optimization approach considering tradeoffs in aerodynamic performance, structural dynamics, weight, solar energy capture, battery storage, electric propulsion, and cost. We are developing design tools and methodologies, and working on different aircraft design concepts and strategies to help make telecommunication access available in more parts of the world.

Wind Turbine Design

Wind turbines are complex multidisciplinary systems that operate in a fundamentally unsteady environment. Blade design is particularly challenging as the blades are often long and slender, make extensive use of composites, and are subject to cyclic and unsteady loading. Similarly, towers must be strong and lightweight and drivetrains must withstand all required mechanical loads. We develop efficient multidisciplinary models to capture complex aerodynamic, structural loading, and economic tradeoffs. Using optimization we explore novel configurations and wind farms that use more than one type of turbine.