Experiment No. 1
Fluid Flow Measurements
Cabreros, Ken Nicles
To measure volume flow rate of fluid like air at various loads, by use of pitot-static tube, venture meter, and orifice flow meter.
Fluid flow measurements are performed across the breadth of engineering, eg. flows of oil, gas, petrol, water, process chemicals, effluent are all necessarily and routinely measured. In the research laboratory, advanced flow measurements are providing new insights into a wide range of engineering flow problems in hydrodynamics (eg. wave impact loading on coastal defenses, beach erosion) combustion (eg. low NOx burners, IC engines), ...view middle of the document...
Stagnation pressure is the point in the center stream of the fluid flow where the velocity becomes zero. The fluid flows into the opening,thus, pressure builds up and remains stationary at the stagnation point. The difference of the static pressure and stagnation pressure represents the pressure rise. It measures the difference between the pressures in the two tubes to obtain the relative velocity of a fluid in motion.
The Venturi meter (after Giovanni Venturi, 1746−1822) is designed to cause minimal head loss as the flow passes the restriction. It is a short tube with a tapering-in construction to have a throat at mid-length of tube that causes increase in the velocity of e flow of fluid and a corresponding decrease in fluid pressure and followed by the tapering-out to original diameter of the tube. The quantity of fluid flow in the venturi meter is determined by the equation:
Q =C2gP1-P2W1-A22A12 (1)
Where C = coefficient of discharge of venturi meter
A1= Cross sectional area of pipe at station 1
A2= Cross sectional area of throat of venturi meter
W= Specific weight of air in the manometer
g = acceleration due to gravity
Orifice in a pipe or duct is an opening in a thin plate obstruction inside apipe of duct line used as flow rate measuring device. It consists of concentric sharp edged circular hole in a thin plate that is clamped between the flanges of the pipe or duct. The flow characteristics is the minimum cross section of the stream occurring further downstream from the obstruction plate.
The quantity Q of the fluid flow is similarly obtained from the equation for the venturi meter. However, several factors contribute to the contracting of flow cross section that a coefficient K replaces the coefficient of discharge of the venturi meter, thus
Q =K2gP1-P2W1-A22A12 (2)
Where K = coefficient of flow of orifice flow meter
III. Materials and Equipment
Fig. 1 Pitot-Static tube
Fig. 2 Venturi Meter
Fig. 3 Manometer
Fig. 4 Set of Circles and Bamboo Corks
Fig. 5 Damper and Orifice Flow Meter
The manometer (Fig. 3) was placed on solid mounting, leveled accurately and the built-in level was adjusted to zero. Initial reading of the manometer was recorded to read the small pressure differential. Cross section of the duct (Fig. 1) was subdivided into sixteen regions of equal areas and pitot tube was allowed to transverse each station.
While the damper was set (Fig.5), the air temperature and barometer reading were recorded. The damper was set at point 1 during the use of pitot tube (Fig. 1), venturi meter (Fig. 2) and orifice flow meter (Fig. 5).
The pitot-static tube was connected in such a way that the static pressure was read from the tube manometer. Rubber tubing was connected with the static pressure connection of the...