Fluid Measurement and Similitude Flashcards
What is a pitot tube?
A hollow tube that is placed longitudinally in the direction of fluid flow, allowing the flow to enter one end at the fluid’s velocity of approach.
What is a pitot tube used for?
It is used to measure the velocity of flow.
What happens in a pitot tube?
When fluid enters the pitot tube, it is forced to come to a stop at the stagnation point, and its kinetic energy is transformed into static pressure energy.
What equation can be used to find the stagnation pressure at the stagnation point?
The Bernoulli equation.
How do you find the upstream fluid velocity in a pitot tube?
Since the velocity of the fluid inside the tube is zero, the upstream velocity can be calculated if the static and stagnation pressures are known.
What does the differential manometer do in a venture meter?
It measures the difference in static pressures between the throat and upstream points.
What is a venture meter used for?
To calculate the flow rate of the fluid.
What is the orifice meter used for?
It is used to measure flow rates in small pipes.
What is the vena contracta?
The point of minimum area and minimum pressure in a orifice meter.
What is similitude or mechanical similarity?
A model that can be used to predict the performance of the prototype.
What does complete mechanical similarity require?
It requires geometric, kinematic and dynamic similarity.
What is geometric similarity?
Means that the model is true to scale in length, area, and volume.
What is kinematic similarity?
Requires that the flow regimes of the model and prototype be the same.
What is dynamic similarity?
Means that the ratios of all types of forces are equal for the model and the prototype.
How is complete dynamic similarity achieved?
When all the similarity laws are satisfied.
