Ultrasonic flowmeter cia siab rau kev nthuav tawm ntawm ultrasonic tsis nyob hauv nruab nrab ntws los sau cov ntaub ntawv ntws ntawm cov kua dej, thiab cov tau txais ultrasonic tsis tuaj yeem kuaj xyuas cov dej ntws, thiab tom qab ntawd hloov mus rau hauv tus nqi ntws.
Lub ultrasonic flowmeter xam qhov ceev thiab ntws ntawm cov kua raws li lub sij hawm sib txawv ntawm lub propagation ntawm lub ultrasonic yoj nyob rau hauv cov kev taw qhia rau pem hauv ntej thiab rov qab kev taw qhia nyob rau hauv cov kua.
Cov sensors nyob rau hauv tus dej ntws thiab downstream ntawm qhov ntsuas yuav ib txhij emit ultrasonic pulses, ib tug yog propagated upstream thiab lwm yam yog propagated upstream. Kev nthuav tawm ceev ntawm ultrasonic mem tes nyob rau hauv pem hauv ntej txaus yog ceev tshaj qhov uas nyob rau hauv lub rov qab ntws. Vim tias qhov kev ncua deb ntawm ob lub pulses yog tib yam, qhov sib txawv ntawm lub sijhawm sib kis ncaj qha cuam tshuam qhov loj ntawm cov dej tshaj tawm. Qhov loj dua lub sij hawm sib txawv ntawm ob lub ultrasonic pulses, qhov loj dua tus nqi ntws.
θ yog lub kaum sab xis ntawm lub acoustic beam thiab ntws cov kev taw qhia ntawm cov kua, M yog tus naj npawb ntawm linear propagation ntawm lub acoustic beam nyob rau hauv cov kua, D yog lub cheeb ntawm cov yeeb nkab, T1 yog lub sij hawm propagation ntawm lub acoustic beam nyob rau hauv cov kua. Cov kev taw qhia zoo, T2 yog lub sijhawm nthuav tawm ntawm cov kab hluav taws xob acoustic nyob rau hauv qhov kev taw qhia rov qab, ΔT yog lub sijhawm sib txawv, ΔT=T1 -- T2.