Shawn Siroka, a doctoral student in the Penn State Department of Mechanical Engineering, has developed new heat flux sensors in gas turbine engines. Siroka is one of the researchers in the Steady Thermal Aero Research Turbine (START) Laboratory focused on advancing turbine energy production by understanding how they mitigate and handle extreme temperatures.
“People have been studying heat transfer for more than 300 years,” Siroka said in an article appearing on Penn State’s website. “We have a good grasp of it, but since it’s such an incredibly complex subject, there is still room for me to explore and try new things.”
Research gas turbines, like those housed in the START Lab, are critical tools for both industry and government, where new ways to improve the technology’s efficiency and performance are investigated and eventually implemented in power plants and jet engines. Particularly, Siroka’s research has delved into thin film heat flux gauges (HFGs), which are flexible sensors that measure temperatures in these test turbines.
“Essentially, these HFGs are measuring the energy that goes in or out of the turbine blade,” he said. “Having that data helps predict the lifecycle or durability of the part and also helps you understand how effectively that part is being cooled.”
Siroka teamed with Karen Thole, distinguished professor, mechanical engineering department head and the START Lab director, and Reid Berdanier, assistant research professor of mechanical engineering, in visiting the University of Oxford in 2019. There, researchers have developed HFGs to be used within their short-duration turbines. The Penn State team sought to understand the challenges they’d face in using these components for the START Lab’s continuous-duration needs.
“We were able to take what we learned and bring it back to the START Lab,” Siroka said. “We decided we would expand on what Oxford has previously done while leveraging our resources at Penn State, specifically the Nanofabrication Lab.”
The challenge posed to the researchers had added complexity. The use of HFGs has largely been limited to short-duration turbines, which typically operate on a scale of minutes or seconds at a time. In comparison, the START Lab’s signature continuous-duration equipment regularly operates for 8-10 hours a day to provide more in-depth data and analysis of the turbine, closer mimicking a real-world application.
“When gas engines operate on a plane or in power generation, they are always operating in a steady condition, like the facilities at the START Lab,” Siroka said. “That means when we are conducting tests in steady conditions, we can do a more apples-to-apples comparison.”
Siroka’s work detailed the nanofabrication process for these improved HFGs and provided a better calibration method to address the potential deterioration of the instruments, which becomes critical when the component is subjected to the harsher exposure of a continuous-duration rig.