Lecture 4 Flashcards
stagnation pressure =
total pressure when C is zero, P +0.5densityC^2 = total pressure
types of instruments for measuring velocity and flow rate
pitot tube
pitot static tube
oriface plate
venturi meter
U tube manometer
change in pressure = P2 - P1
U tube manometer equation
see powerpoint
adv of utube manometer
reliable (gravity doesnt change much)
accurate
disadv of utubue manometer
difficult to setup no electronic readout mercury used is toxic needs to be level (liquid cant slosh around) slow
use of utube manometers
calibrating other pressure gauges
pitot tube diagram
see powerpoint
change in pressure =
(density of liquid - density of fluid) * g * height difference
pitot static tube adv
can be made small
cheap robusy simple accurate close to point measurement
disadv of pitot static tube
slow response
must point directly into flow
venturi meter actual volume flow rate
discharge coefficient * ideal volume flow rate
what is beta for a venturi meter
D/d
venturi meter equation
see powerpoint
discharge coefficent =
actual velocity/ideal velocity
pressure recovery diagram
see powerpoint
beta for oriface plate
d/D
what is epsilon in the orifice plate equation
expansibility factor 1 for incompressible fluids
how to solve oriface plate equation and why
iterative approach as reynolds number is in the equation for discharge coefficient
why is the discharge coefficient lower for oriface plates than venturi meters
due to greater number of eddies in the expansion and the reduction
p terms for a tank or reservoir equal to
pressure above fluid - if open tank then it is atmospheric if closed tank = pressure above tank
discharge velocity from a nozzle pressure =
atmospheric pressure
