| Anemometry is the measurement of wind force and velocity. Though anemometry technology is fairly well developed, many velocity measurement devices are expensive, large, and/or fragile. Due to these limitations, deploying large numbers of anemometers is difficult, and often unrealistic. The miniature optical-based velocity probe is a new instrument that offers advantages over current state-of-the-art anemometers in terms of lower expense, lower power consumption and lighter weight. The probe consists of a high performance plastic optical fiber, a vertical-cavity surface-emitting laser (VCSEL), and a position sensitive detector (PSD). Light transmitted by the VCSEL shines through the free end of the optical fiber illuminating the surface of the PSD. A drag force, induced by an approach flow, causes the optical fiber to deflect. The PSD measures the deflection of the optical fiber and outputs an analog voltage, which can be directly related to velocity through a calibration curve. Equations for the deflection and natural frequency of the optical fiber, along with numerical simulations in FLUENT were used to make key design decisions in order to optimize the probe to meet the target specifications for atmospheric research. Preliminary calibration experiments show that the velocity probe has the potential to be a viable replacement for other research-quality anemometers. |
