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JRI Research Team Develops Very Low Cost Device that Transforms Directional Anemometers into Unidirectional Anemometers



Two students from different Southern California high schools participated in a research project that developed a novel device which, when placed around an anemometer that measures wind speed for wind moving in one direction, can transform that same anemometer into a device that accurately measures wind speed from any direction. This is accomplished by redirecting the wind moving past the new device so that it passes through the anemometer in a preferred direction and measuring this wind as it passes through.


The group, consisting of Anoushka Bose of Francis Parker High School in San Diego, Timothy Lee of Arcadia High School in Arcadia, and their Research Mentor noted that the way that air flows over curved objects affects their wind speed and the detailed pressure around them. They reasoned that if air were flowing around an object with a larger curvature on one side, it would move faster and thereby generate a lower pressure at the surface. This is precisely how wings on airplanes function. If the pressure on one surface was higher than that on another, a hole bored through might generate an jet of air in the object. When they made a crude model out of piping, wood, and paper, the idea seemed to work.


Originally, the group's hope was to use the internal jet to generate a lateral thrust – a thrust that might push the object sideways. This would be accomplished by redirecting the airflow internally, generating a sideways push. If enough of these were placed in a circle, they reasoned, the combined thrust might be enough to generate a rotation. Yet they soon realized that the thrust one might expect from the push was so small that they could not expect it to be useful.


The team eventually also realized that the wind that flowed vertically through their devices, dubbed “windbenders” by the group, didn't depend on the direction it was coming from. This meant that if the anemometer they were using, a hot wire-type anemometer that measures the cooling of an electrically heated wire, could be calibrated to measure the current wind speed using the slower internal jet, the device could be used as an omnidirectional anemometer.  Moreover, the final device can be made from epoxy-coated styrofoam, which can be quite durable and extremely cheap to make either as a completed product or as a one-off prototype.

A diagram of a directional anemometer embedded in a windbender.


In order to test their plan, the group constructed a wind tunnel and used it to experimentally test the devices. They also constructed several prototypes and used this to determine efficacious designs of the device. The plan worked and they were able to perform the calibration on several different versions of the devices. The group compiled their results in a scientific paper entitled A Differential Pressure Anemometer”, submitted it to the 2015 International Conference on Remote Sensing and Development, and were invited to Auckland, New Zealand to present their research results. The paper will be published in the conference proceedings.


Interestingly, this meant that although the idea didn't work well as a windmill, it did work well as an envelope for a directional anemometer. The project had the added bonus lesson that sometimes science doesn't go where you think or hope it will; sometimes it generates results very different from expectations. 


Timothy Lee is now a freshman at the University of California, San Diego. Anoushka Bose is a senior, currently preparing college applications.


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