Bernauli Flashcards
(21 cards)
What is flow in fluid dynamics?
Flow is a measure of the volume of fluid that flows per unit of time. Units are, for example, litres per minute.
Define mass flow rate.
Mass flow rate is the mass of fluid passing a point in a system per unit of time. Units are, for example, kg/s.
What does flow velocity refer to?
Flow velocity refers to how quickly the fluid is moving, measured in m/s.
How is pressure defined in fluid dynamics?
Pressure is a measure of force applied on an area. Units are, for example, N/mm² or Pa.
What is viscosity?
Viscosity is a measure of a fluid’s resistance to deformation at a given rate.
What is an incompressible fluid?
An incompressible fluid is one whose density does not change when the pressure changes.
State Bernoulli’s principle.
Bernoulli’s principle states that an increase in the speed of a fluid occurs simultaneously with a decrease in pressure or potential energy.
What does the Bernoulli equation represent?
The Bernoulli equation represents the conservation of energy principle applied to flowing fluids.
What is the relationship between pressure and flow velocity according to Bernoulli’s principle?
In regions where flow velocity increases, fluid pressure decreases.
State Bernoulli’s equation.
P + 0.5ρv² + ρgh = constant.
What assumptions does Bernoulli’s equation make?
- The fluid has constant density/is incompressible
- The flow is steady
- There is no friction.
How is mass flow rate calculated?
Mass flow rate = ρvA.
What happens to mass flow rate when pipe diameter changes?
The mass flow rate must be the same at all points along the pipe.
Fill in the blank: The volume flowing through a hydraulic system can be found by multiplying the cross sectional area by the _______.
[flow velocity]
What is the formula for pressure in a hydraulic system?
Pressure, P = force × area.
What is the effect of a tapered pipe on flow velocity?
A change in the cross sectional area changes the flow velocity.
True or False: Bernoulli’s principle can be used to calculate the lift force on an aerofoil.
True.
What results from the pressure difference above and below an aircraft wing?
An upwards lifting force (lift).
How is lift force calculated using Bernoulli’s principle?
Lift forces can be calculated using Bernoulli’s equations when the distribution of speed is known.
What is the unit of measure for viscosity?
The unit of measure for viscosity varies but is commonly expressed in Pascal-seconds (Pa·s).
Fill in the blank: The qualitative behaviour associated with Bernoulli effect is the lowering of fluid pressure in regions where the flow velocity is _______.
[increased]
