{"id":5484,"date":"2020-02-06T09:14:00","date_gmt":"2020-02-06T08:14:00","guid":{"rendered":"https:\/\/www.presticebdt.com\/?p=5484"},"modified":"2023-09-23T13:32:34","modified_gmt":"2023-09-23T11:32:34","slug":"hot-wire-anemometer-and-flow-measurement","status":"publish","type":"post","link":"https:\/\/www.presticebdt.com\/el\/hot-wire-anemometer-and-flow-measurement\/","title":{"rendered":"\u039c\u03ad\u03c4\u03c1\u03b7\u03c3\u03b7 \u03c1\u03bf\u03ae\u03c2 \u03b1\u03ad\u03c1\u03b1: \u03b5\u03c0\u03b5\u03be\u03ae\u03b3\u03b7\u03c3\u03b7 \u03b1\u03bd\u03b5\u03bc\u03cc\u03bc\u03b5\u03c4\u03c1\u03bf\u03c5 \u03b8\u03b5\u03c1\u03bc\u03bf\u03cd \u03c3\u03cd\u03c1\u03bc\u03b1\u03c4\u03bf\u03c2"},"content":{"rendered":"

\u00a0Air Flow Measurement: hot wire anemometer<\/h1>\n

Experimental aerodynamics: how hot wire anemometer tecnique works<\/h2>\n

Air flow measurement and hot wire anemometer.
\n<\/strong><\/h3>\n

In the study of experimental aerodynamics, it is necessary to know the speed of the flow<\/strong> and to have indications on the air flow (in our case) that surrounds a body.<\/p>\n

\u03a4\u03bf flow meter<\/strong> is the instrument for measuring the flow rate, volumic or mass, of a fluid, liquid or aeriform.<\/p>\n

What is a hot wire anemometer?<\/h4>\n

The hot wire anemometer is precisely a static flow meter<\/strong>, normally used to determine the air speed in ventilation ducts. It is composed of a resistance thermometer<\/strong>, that means a resistance whose value is proportional to the temperature<\/strong>, which is fed by an electric current of known intensity, such as to bring it to a temperature higher than that of the fluid to be measured. This resistance is immersed in the fluid whose speed is to be measured. The fluid will cool the resistance proportionally to its speed<\/strong> allowing it to go back to it.<\/p>\n

\"Hot<\/a>

Hot wire anemometer.<\/p><\/div>\n

The advantages of this instrument are mainly due to the very small dimensions<\/strong> that can be taken by the probe. This allows you to make measurements in various positions in the pipe, to disturb the flow of the fluid in a minimal way, to have a very high response speed (in the order of kHz)<\/strong> that allows you to detect the speed variations due to turbulence.<\/p>\n

The disadvantages are related to the dependence of the calibration on various factors such as the characteristics of the fluid, its pressure and its temperature.<\/p>\n

How the hot wire anemometer works?<\/h3>\n

\u03a4\u03bf operating principle of HWA<\/strong> – Hot Wire Anemometer<\/strong> – at constant wire temperature is positioned with an axis perpendicular to the current speed of a known flow.<\/strong> The probe allows to measure instantaneous physical quantities (which vary over time). A hot wire probe is indispensable for detecting, for example, the fluctuations present in the turbulent boundary layer or also instantaneous quantities in other turbulent flows such as the jet and the wake.<\/p>\n

To perform this function, hot wire anemometry must meet the following requirements:<\/p>\n