Portland State Magazine Winter 2008

Weislogel's specialty may be obscure, but the basic concept is simple. On Earth, fluid management systems like water mains and automobile fuel tanks work with gravity to move their contents around. Weislogel and his co-investigators, including Purdue University's Steven Collicott, are investigat– ing how the shape and dimension of their containers can help move liquids when gravity doesn't apply. While the immediate applications of chis technology are improved water and fuel systems for spacecraft, there is also an extensive array of poten– tial applications here on Earth. "The better we understand how capillary flow works in space, the better we can make these systems work on the ground," Weislogel says. "The possibilities are limitless for things like biological scaffolds"-peptide-based, laboratory– grown support systems chat can help spinal cord injury patients regenerate nerve tissue, "high-efficiency fuel cells chat rely on capillary flow, and things like better laptop cooling systems, which are driven by wicking." BY DAY, WEISLOGEL can be found in a PSU classroom, teaching courses in Applied Fluid Mechanics and Thermo– dynamics as well as Capillary Flows and Phenomena. In his "spare" time, he and his grad students are immersed in grant– funded research for NASA, the National Science Foundation, and private corporations. Most of the experiments they design are focused on unlocking the mysteries of capillary flow, including what happens when the surface of a liquid comes into contact with a solid. "Wicking"-the phenomenon chat occurs when you dip the corner of a paper towel in water-is one example of capillary flow. On Earth, gravity tends ro overwhelm and dampen capillary force. But in space, in the near-absence of gravity, capillary forces express themselves freely. Introduce a rotating vane to a specially designed vessel, for example, and the agitated liquid-silicone oil, in the case ofWeislogel's NASA experi– ments-reacts far differently than it does on Earth. Careful review of the ultra-slow-motion videos of the zero-g NASA experiments reveals nuances of liquid behavior that exponen– tially multiply the data Weislogel and his colleagues would obtain from a similar, earthbound experiment. NASA is interested in Weislogel's research because of the unique engineering challenges inherent in a zero-g environ- In his campus lab, Prof. Mark Weislogel's work is bound by gravity, unlike his capillary flow experiments aboard the International Space Station, which astro– nauts have conducted on at least seven expeditions. ment. Instead of hugging the bottom of the tank as it does on Earth, liquid rocket fuel, for example, becomes a free-floating blob of liquid, reacting to the motion of the shuttle vehicle. The less fuel is in rhe tank, the more room the "blob" has to move around, and the more acute the problem becomes. "Aboard the shurde, you don't want to have liquid shifting unpredictably from one side of a container to the ocher," Weislogel says. "It may sound like a small thing, but when you're talking about 80,000 pounds of rocket fuel, that's a pretty significant weight shift. If you didn't predict it, that would be very bad; Ir would shift the entire center of gravity on the ship." By changing the geometry of the containers used to carry liquids on board the shuttle-say, from a cylinder to an ellipse-and introducing simple elements like internal vanes to shift the liquid from one part of the container to another, Weislogel and colleagues are helping NASA solve such vex- ing problems. "Most of the older systems rotated to produce artificial gravity," he explains. "That adds risk, mass, and power draw. The solutions we're designing are more passive and elegant. They may or may not perform as well, but then again, they may not need to." BECAUSE NASA IS PLEASED with the information gen– erated by Weislogel's 19 capillary flow experiments aboard the International Space Station, it has asked him to help design the futuristic fluid delivery systems aboard its next-generation Crew Exploration Vehicle (CEV). The CEV, currently sched– uled for deployment in 2014, will be capable of carrying a crew of four into lunar orbit. It's an exciting prospect. But for now, Weislogel is keeping his feet firmly on the ground. After a career that included 10 years at NASA and a stint at a private aerospace firm in Colorado, he chose Portland State. "I wanted to come to PSU because it was the most inter– esting place in the Northwest that I looked at," Weislogel says. "I felt PSU was on the rise, and I wanted to be a part of that. I love the whole student-teacher thing. I love helping my students along their path and firing them up about sci– ence. They're really good-they can do anything. I really like chem-don't tell them chat, but I do." ■ WINTER 2008 PORTLAND STATE MAGAZINE 17