Zasnova merilnika pretoka in smeri zraka

STRMEC, JERNEJ (author), Trontelj, Janez (mentor)

V magistrski nalogi smo opisali razvoj anemometra, ki mora biti poceni, brez premičnih delov, enostaven za izdelavo in porabiti čim manj energije. Kot merilni element smo izbrali diodo zaradi linearnosti spremembe napetosti v odvisnosti od temperature. Pri merjenju smo uporabljali dva senzorja: referenčnega, ki je služil za temperaturno kompenzacijo meritve, in merilnega, ki smo ga segreli in merili hitrost njegovega ohlajanja. Vsak senzor je bil sestavljen iz para zaporedno vezanih diod, s čimer smo dosegli večjo spremembo napetosti pri enaki spremembi temperature. Hitrost pretoka zraka smo izračunali iz meritev spremembe razlike napetosti med senzorjema preko izračuna časovne konstante ohlajanja. V besedilu so najprej opisani različni tipi anemometrov in princip meritve razvitega anemometra na osnovi razlike temperatur med diodama. V naslednjih poglavjih je predstavljen vetrovnik, ki smo ga izdelali za meritve, izbira senzorjev, električna shema in tiskano vezje. Nato smo opisali program za krmiljenje, odčitavanje senzorja in izračun hitrosti vetra, ki smo ga razvili. Na koncu smo opisali proces umerjanja anemometra in predstavili rezultate preizkusnih meritev. Pokazali smo, da izdelani anemometer deluje, a ima meritev s standardnimi, nenamenskimi diodami nekatere omejitve, kot na primer dolg čas meritve. Tak anemometer bi bil lahko uporaben pri vseh meritvah pretoka zraka, pri katerih lahko zagotovimo laminaren pretok zraka.

• Language: Slovenian
• Keywords: anemometer z vročo žico, ocena termične časovne konstante, temperaturna kompenzacija, diode, senzorsko tiskano vezje
• Work type: Master's thesis/paper
• Organization: FE - Faculty of Electrical Engineering
• Year: 2021
• PID: 20.500.12556/RUL-124438
• Publication date in RUL: 21.01.2021

STRMEC, JERNEJ, 2021, Zasnova merilnika pretoka in smeri zraka [online]. Master’s thesis. [Accessed 8 March 2025]. Retrieved from: https://repozitorij.uni-lj.si/IzpisGradiva.php?lang=eng&id=124438

Secondary language

• Language: English
• Title: Air Flow And Air Flow Direction Measurement System Design

Abstract

In the master's thesis we described an anemometer's development, which must be cheap, without moving parts, easy to manufacture and consume as little energy as possible. The diode was chosen as a measuring element due to the voltage change's linearity as a temperature function. We used two sensors in the measurement: a reference, used to compensate for the ambient temperature changes, and a measuring one, which was heated and its cooling rate was measured. Each sensor consisted of a pair of diodes connected in series, thus achieving a more considerable voltage change at the same temperature change. We calculated the air flow rate from measurements of the voltage difference between the sensors by calculating the cooling time constant. The text first describes the different types of anemometers – also, the measurements of the developed anemometer based on the diodes' temperature difference. The following sections present the wind tunnel we designed for the measurements, sensor selection, wiring diagram, and printed circuit board. We then described the control program, sensor reading, and wind speed calculation we developed. Finally, we described the anemometer calibration process and presented the results of experimental measurements. We have shown that the developed anemometer works, but the measurement with standard, general-purpose diodes has some limitations, such as a long measurement time. Such an anemometer could be useful in all air flow measurements where we can ensure laminar airflow.

• Keywords: hot wire anemometer, the thermal time constant estimation, temperature compensation, diodes, sensor printed circuit board