Author/Editor		Bunc, Matjaž; Rozman, Janez
Title		Another way of a liquid flow measurements by using a specially designed turbine
Translated title		Način merenja pretoka tekočin s posebno turbino
Type		članek
Source		Inf MIDEM
Vol. and No.		Letnik 30, št. 3(95)
Publication year		2000
Volume		str. 165-7
Language		eng
Abstract		We designed a special measuring turbine which is suitable for measurements of flow of various liquids in laboratory and animal experiments in medicine. Specifically, the turbine was designed for measurements of blood flow in isolated working pig hearts. The basic principle of measuring of liquid flow through the turbine is based on measurement of the time elapses when the rotor rotates by one degree. For this purpose, the rotor is equiped with circular and transparent foil having a ring of 360 black lines printed near the circumference of the foil and oriented towards its centre. Sensory part is realized using two infra-red light-emitting diodes mounted on one side of the foil and two photo transistors as sensors of the tramsitted infra-red light mounted on the other. By this way, the direction of rotation of the rotor can be identified. The characteristics of electronic part of the turbine are as follows: voltage regulated output, ranging from 0 to +- 2.048 V, factor of a transformation described as 1 revolution of a rotor/s = 500 mV at the output (changeable by the programme), calculating time is 2 ms and resolution is 1 mV (11bits). The electronic part is powered by external power supply of 5V. The turbine showed a linear response at a continuous saline flow up to 3,000 ml min-1 at pressure loads of between 20 and 220 cm H2O. Pressure drop across the turbine depends on the volume flow and was 1 mmHg at 100 ml min-1 and 5mmHg at 7,000 ml min-1. A rotating moment 1.25x10-4 kg m2 s-1 was calculated. The lowest volume change of a bolus of saline solution, detected by the turbine, was 1.6 ml. Similar, suitable adapted turbine could be used also for measurments of much bigger liquid flows.
Summary		Izdelali smo posebno merilno turbino, ki je primerna za merenje pretoka različnih tekočin pri laboratorijskih in živalskih poskusih v medicini. Pravzaprav smo izdelali turbino za merenje pretoka krvi na izoliranih paršičjih srcih. Osnovni princip merjenja pretoka tekočin skozi turbino sloni na merenju časa, ki preteče, ko se rotor turbine zavrti za eno stopinjo. V ta namen je na rotor nameščena okrogla, prozorna folija, na kateri je v bližini oboda natisnjenih 360 kratkih, pol stopnje širokih, v redišče usmerjenih črnih črtic. Senzorski del je realiziran tako, da sta na eno stran folije nameščeni dve infrardeči svetleči diodi in na drugo stran dva foro transistorja. Tako lahko določimo tudi smer vrtenja turbine. Karakteristike elektronskega dela turbine so: napetostni izhod v območju od 0 do +- 2.048 V, faktor pretvorbe 1 ibr/s = 500 mV, zgornja meja (programsko dolčeno) 2.048 V, čas izračuna 2 ms in resolucija 1 mV (11 bitov). Elektronika je preko omrežnega pretvornika napajanja z enosmerno napetostjo 5V. Pri tlakih v območju med 20 in 220 cm H2O in pretokih fiziološke raztopine do 3000 ml/min je signal na izhodu turbine povsem linearno odvisen od pretoka. Padec tlaka na turbini je odvisen od pretočnega volumna in je pri pretoku 100 ml/min enak 1 mmHg ter pri pretoku 7000 ml/min enak 5 mmHg. Vrtilni moment je bil empirično izračunan in znaša 1.25x10-4 kg m2 s-1. Najmanjša sprememba volumna, ki ga zazna turbina je enaka 1.6 ml. Ustrezno predelano turbino je moč uporabiti za merjenje celiko večjih pretokov tekočin.
Descriptors		BLOOD FLOW VELOCITY CARDIAC OUTPUT BIOMEDICAL ENGINEERING SWINE