Week 10 Flashcards
Why do quantities between model and prototype disagree?
Measurement Effects
Model Effects
Scale effects
What type of similarity is necessary for a perfect model-prototype similarity?
Mechanical Similarity, which is made up of:
Geometric similarity
Kinematic similarity
Dynamic Similarity
How is inertial force represented in fluid dynamics?
(rho)(L^2)(V^2)
How is gravitational force represented in fluid dynamics?
(rho)(L^3)(g)
How is viscous force represented in fluid dynamics?
(υ)(L^3)(g)
How is surface tension force represented in fluid dynamics?
sigma*L
How is elastic compression force represented in fluid dynamics?
E*(L^2)
How is pressure force represented in fluid dynamics?
p*(L^2)
Define Froude number, F.
(inertial force/gravity force)^0.5
Define Reynolds number, R.
inertial force/viscous force
Define Weber number, W.
inertial force/surface tension force
Define Cauchy number, C
inertial force/elastic force
Define Euler number, E
pressure force/inertial force
What are scale effects due to with regards to F?
reduced flow velocity
What are scale effects due to in R?
larger viscous losses in model
What are scale effects due to in W?
Too large air bubbles and faster air detrainment
Wave celerit of short wave is affected
Reduced discharge for small water depths
What are scale effects due to in C?
structure interacting with water behaves too stiff and strong.
Water and air are too hard in the model
What are scale effects due to in E?
Cavitation can not be observed in model if atmospheric pressure is not scaled
What is the scale factor for length?
λ
What is the scale factor for mass?
(rho-prototype/rho-model)*(λ^3)
What is the scale factor for mass moment of inertia (J) ?
(rho-prototype/rho-model)*(λ^5)
What is the scale factor for area moment of inertia?
λ^4
What is the scale factor for water velocity?
λ^0.5
What is the scale factor for air velocity?
(λ^0.5)*(1/Beta)
What is the scale factor for acceleration?
1
What is the scale factor for time?
λ^0.5
What is the scale factor for frequency?
λ^(-0.5)
What is the scale factor for angle?
1
What is the scale factor for force?
(rho-prototype/rho-model)*(λ^3)
What is the scale factor for moment?
(rho-prototype/rho-model)*(λ^4)
What is the scale factor for stiffness?
(rho-prototype/rho-model)*λ
What is the scale factor for stress?
(rho-prototype/rho-model)*λ
What is the scale factor for power?
(rho-prototype/rho-model)*(λ^3.5)
What is the scale factor for thrust coefficient?
(rho-prototype/rho-model)*(Beta^2)
