Frequent fliers know that extreme weather can keep them grounded.
It may be inconvenient, but there’s good reason why airlines follow rigorous operating procedures during ice and snow conditions. The Air Florida Flight 90 crash in 1982 and USAir Flight 405 crash in 1992 are just two examples of catastrophic failure directly attributed to snow and ice buildup on aircrafts.
When ice droplets accumulate and freeze on the wings of airplanes, they cause a serious safety hazard. A buildup of ice on the wings, horizontal stabilizers and tail not only adds weight, but more importantly affects the flow of air over the airplane by increasing drag and reducing lift. A sheet of ice the thickness of a compact disc can reduce lift by 25%, according to the Icing Branch at NASA’s Glenn Research Center.
Ice sensors can have a mitigating effect in detecting ice formation quickly and accurately, noted a research team from the University of British Columbia’s Okanagan’s School of Engineering. Targeting aviation as well as renewable energy industries, the researchers are focusing their latest research on improving the real-time response of the sensors to determine frost and ice buildup.
Assistant professor Mohammad Zarifi and his team at UBCO’s Okanagan MicroElectronics and Gigahertz Applications (OMEGA) Lab had previously developed a sensor that detects the precise moment when ice begins to form on a surface. They chose microwave resonators based on several criteria: high sensitivity, low power, ease of fabrication and planar profile.
A microwave resonator sensor with built-in heating capability was patterned into the plane. Sensing tests were performed on surfaces with anti-icing coatings as a way to test the effectiveness of the materials. In addition, the split-ring resonator was assessed for its ability to evaluate various de-icing methods. Operating at 5.82 GHz, the sensor could effectively distinguish between ice and water by detecting changes in the dielectric properties around its surface.
The sensors can identify ice accumulations in real-time while calculating the rate of melting. This is crucial data for aviation, for keeping flights on time and renewable energy applications, Zarifi explained.
The patented sensor, which includes a protective layer, is currently being tested by the aviation industry through a rigorous approval process, Zarifi noted. The research is funded by the Department of National Defense and will enable the researchers to improve the sensor’s capabilities.
“We received a great deal of interest from the aviation and renewable energy industries stemming from our initial findings, which pushed us to expand the boundaries of the sensor’s responsiveness and accuracy,” said Zarifi.
Meanwhile, the researchers uncovered another first: Their sensor can detect salty ice, which freezes at colder temperatures. Understanding and monitoring saltwater ice formation is of interest because saltwater ice on oil rigs and marine infrastructure can create issues. Zarifi and his team are working toward the introduction of microwave/radar-based technology to meet such challenges.
By incorporating an antenna into the sensor, the results can be shared in real-time with the operator in order to address the buildup, noted Zarifi.
The technology can be modified for various applications including ice and moisture sensing. To this end, the OMEGA Lab is working with a number of wind turbine companies to adapt the sensors into wind farms.
According to Zarifi, the sensors can be mounted at the same altitude of the blades without having to be mounted to the blades. This removes certain calculation variables that are related to motion, making the wind turbine application a slightly more straightforward proposition, he said.
The research was published in the journal Applied Materials and Interfaces.