![]() ![]() Close the screw, after pumping, to retain the pressure in the system. This can be accomplished by attaching the hand pump tube to the air bleed valve, opening the screw, and pumping air into the manometers. If needed, the manometer levels can be adjusted by using an air pump to pressurize them. The maximum flow will be determined by having a maximum (h 1) and minimum (h 5) manometer readings on the baseboard. Open the air bleed screw slightly to allow air to enter the top of the manometers (you may need to adjust both valves to achieve this), and re-tighten the screw when the manometer levels reach a convenient height.Open the bench valve and allow flow through the manometers to purge all air from them, then tighten the air bleed screw and partly open the bench valve and the apparatus flow control valve.Remove the cap from the air valve, connect a small tube from the air valve to the volumetric tank, and open the air bleed screw.Close both the bench valve and the apparatus flow control valve.The following steps should be taken to purge air from the pressure tapping points and manometers:.Gradually open the bench valve to fill the test section with water. Connect the apparatus inlet to the bench flow supply, close the bench valve and the apparatus flow control valve, and start the pump.If the test section needs to be reversed, the total head probe must be retracted before releasing the mounting couplings. Install the test section with the 14° tapered section converging in the flow direction.(A sprit level is attached to the base for this purpose.) For accurate height measurement from the manometers, the apparatus must be horizontal. Level the apparatus base by adjusting its feet.Place the apparatus on the hydraulics bench, and ensure that the outflow tube is positioned above the volumetric tank to facilitate timed volume collections.The velocity of flow at any section of the duct with a cross-sectional area of is determined as:įor an incompressible fluid, conservation of mass through the test section should be also satisfied (Equation 1a), i.e.:Ī YouTube element has been excluded from this version of the text. The flow velocity is measured by collecting a volume of the fluid (V) over a time period (t). ![]() The conservation of energy or the Bernoulli’s equation can be expressed as: This probe is inserted into the duct with its end-hole facing the flow so that the flow becomes stagnant locally at this end thus: The total head (h t) may be measured by the traversing hypodermic probe. In which is called the velocity head (h d). Therefore, Bernoulli’s equation for the test section can be written as: The pressure head (h), thus, is calculated as: The hydrostatic pressure (P) along the flow is measured by manometers tapped into the duct. In this experiment, since the duct is horizontal, the difference in height can be disregarded, i.e., z 1=z 2 These two laws and the definition of work and pressure are the basis for Bernoulli’s theorem and can be expressed as follows for any two points located on the same streamline in the flow: Thus, the input mass and energy for a given control volume are equal to the output mass and energy: These assumptions are also based on the laws of conservation of mass and energy. \)īernoulli’s theorem assumes that the flow is frictionless, steady, and incompressible. ![]()
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