Development and calibration of a self-recording cup anemometer for wind speed measurement

Abstract

The design, development and calibration of a digital wind speed measuring device (cup anemometer) has been carried out. The instrument design consists of six electronics block stages: Power stage which supplies power through either a direct current (DC) or an alternating current (AC), input (sensor) stage which senses the number of revolutions per minute (rpm), the clock/triggering stage which was designed to monitor the time interval between the break and makeup of the pulses, and the output stage which comprises the counting stage, decoders/memory stage and lastly the seven segment display. Each block was designed in stages, simulated and constructed to give the required output, utilizing various low-power integrated circuits (ICs). The output results were then interfaced to give the final desired result. The mechanical aspect of the device was composed of a casing and three conical shape cups which was made from acrylics materials, aluminium spindle with bearings. The device after development was calibrated against the standard (Delta-T) anemometer, type ANI for accuracy and performance evaluation. The calibration statistics showed a high correlation coefficient r = 0.93 at P ≤ 0.05 between the standard and the developed anemometer. Also, sensitivity analysis of the developed anemometer gave 1.2 rpm/ms^-1. The developed instrument is useful in climatic studies especially in areas of irrigation agriculture, aviations, pollution control and radioactive development.

Key words: Wind speed, cup anemometer, sensor, decoder, spindle.