Christensen Receives NSF CAREER Award

Assistant Professor Kenneth Christensen was one of four University of Illinois faculty members to receive a 2007 National Science Foundation CAREER Award. The Award will provide five years of funding for Christensen to study coupled roughness/pressure-gradient effects and reduce the complexity of highly irregular roughness in wall turbulence. The NSF CAREER Award recognizes and supports the activities of scholars early in their careers. Awardees are often considered to be emerging leaders in their respective fields.

Christensen, who is also the recipient of a 2006 Air Force Office of Scientific Research Young Investigator Award, is interested in studying the complexities of technologically relevant flows. One example is the flow over turbine blades where both surface roughness and strong pressure gradients can have a profound impact on the efficiency of both airborne and land-based turbines. He is particularly interested in understanding how the surface irregulartities that develop over time on turbine blades--due to pitting, deposition and other wearing--affects the air flow around them. He uses digitized topologies of actual damaged turbine blades to reconstruct three-dimensional topological models of the highly-irregular surfaces using power-deposition printing technology. The flow over the surface replicas is then studied in a boundary-layer wind tunnel using particle image velocimetry.

A key goal of the NSF grant will be to determine the coupled impact of highy irregular surface roughness and strong pressure gradients on the flow. Such influences often occur on the pressure surface of a turbine blade, where surface damage is most pronounced and strong favorable pressure gradients exist. Such knowledge may help improve predictions of turbine efficiency over time and ultimately extend turbine lifetimes.