I enjoyed developing three experiments with the ZeroG Team during my undergrad at UW-Madison. Participating in NASA’s Reduced Gravity Student Flight Opportunities Program, I joined students from across the nation in designing experiments to be performed in a microgravity environment. Over three years, we submitted three research proposals, and NASA selected two of these experiments for investigation aboard the DC-9B Weightless Wonder. This plane achieves microgravity (zero-g) by flying a parabolic path, during which the plane, occupants, and experiments experience zero gravity for 30 seconds. My flights capped 11 consecutive years of UW experiments in this program; see below for descriptions.
2006-7: Measuring Capillary Forces in Microgravity
Our team designed an experiment to research capillary action in microgravity. Capillary action is the phenomena that allows plants to transport liquid from their roots up to the highest branches. In contrast to terrestrial applications, microgravity fluid systems cannot rely on gravity to collect fluids; instead the absence of gravity often ‘allows’ fluids to get trapped in the corners of tanks far from the tank exit. In these cases, the fluid cannot be drawn out of the tank, and though unspent, is useless. To better understand this situation, this experiment measured the flow velocities of two liquids as they flowed up five differently-angled surfaces (see video, below). These velocities are a function of the fluid properties and the surface geometry; interpreting our results will guide fluid system design to avoid trapped-fluid scenarios. This research can also be applied to transporting fluids in space without pumping.
2007-8: Spray Cooling in Microgravity
In this experiment we researched the effectiveness of spray cooling in microgravity. Spray cooling uses an array of nozzles to create a turbulent fluid mixture on some hot device for the purpose of cooling that device. The hot device may be a microprocessor or laser diode, where instead of a heat sink and/or fan (as you find in your computer), we’re using a liquid cooling loop with fluid sprays that impinge on the heated surface. Whereas the amount of energy that heat sinks can dissipate limited by the velocity and ‘energy absorption capability’ of air, using a liquid provides a substantially greater capability. A simple schematic of the test chamber is below, as are our documents. This research was presented at the 2009 Space, Propulsion, and Energy Sciences International Forum in Huntsville, AL.
2008-9: Continued Investigation of Linear Spray Cooling
Our previous spray cooling experiment answered some questions but motivate a number of others. In my Junior year we proposed a new array design and a more thorough characterization of spray cooling in microgravity. The new array design was precisely machined from a single piece of aluminum, as opposed to the array of tubes used in previous linear spray arrays. Unfortunately, NASA’s support was reduced by 2/3rds and we were not selected to fly this experiment.
The new array concept:
As mentioned, UW has been active in this program for a number of years; here are some of the materials I’ve collected which document our research.