Liquid kerosene flows through a venturi meter, as shown in fig. p1.36. the pressure of the kerosene in the pipe supports columns
of kerosene that differ in height by 12 cm. determine the difference in pressure between points a and b, in kpa. does the pressure increase or decrease as the kerosene flows from point a to point b as the pipe diameter decreases? the atmospheric pressure is 101 kpa, the specific volume of kerosene is 0.00122 m3/kg, and the acceleration of gravity is g 5 9.81 m/s2.
We know Pa=Patm+dgh+dgl here Pa is pressure in pipe with higher level of liquid Patm is atmospheric pressure d is density g is gravitational constant h is height of lower liquid l is difference is height of higher liquid So Pb= Patm+dgh here Pb is pressure lower level pipe so Pdiff=Pb-Pa Pdiff=-dgl We know Density of kerosene is the reciprocal of it’s specific volume so d=1/v=1/0.00122=820kg/m3 as g=9.81 and l=12cm Pdiff= - 820*9.81*12/100 Pdiff = -965.304 Pa
Negative sign shows pressure decreases as the kerosene flows from point A to point B as the pipe diameter decreases.