SLIDE 1
Rho vee aaaah
0 = Σ [휌V⟂A]incoming + Σ [휌V⟂A]outgoing
For steady flow through a fixed volume.
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Danger
(휌|V⟂|A)1 = (휌|V⟂|A)2 “if A increases, then V must decrease”
- der?
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Rho vee aaaah 0 = [ V A ] incoming + [ V A ] outgoing For steady - - PowerPoint PPT Presentation
Rho vee aaaah 0 = [ V A ] incoming + [ V A ] outgoing For steady - - PowerPoint PPT Presentation
Rho vee aaaah 0 = [ V A ] incoming + [ V A ] outgoing For steady flow through a fixed volume. 1|10 Danger (| V | A ) 1 = (| V | A ) 2 if A increases, then V must decrease oder? 2|10 Photo US Navy (1961,
SLIDE 2
SLIDE 3
Photo US Navy (1961, public domain) 3|10
SLIDE 4
Photo CC-by-sa by Airwolfhound 4|10
SLIDE 5
Photo by Lori Losey / NASA (public domain, 2007) 5|10
SLIDE 6
Rolls-Royce Spey
Photo CC-by-sa Arjun Sarup 6|10
SLIDE 7
Possibly Wrong Fluid Mech
1 only true if 휌 remains constant.
OK for water flows. No heat transfer, no expansion! Supersonic flow: A ↘ can lead to V ↘ because 휌 ↗.
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SLIDE 8
Smaller A, larger V?
Photo CC-by by Amy Stanley 8|10
SLIDE 9
Possibly Wrong Fluid Mech
2 There is no causal relationship.
A2 ↘ may mean V2 ↗, but... nothing guarantees A2V2 remains constant! (maybe ̇ m ↘). Increases in velocity are not “for free”: they require force be applied and energy be spent.
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SLIDE 10
Are you using the mass balance equation to predict velocity? → also ask yourself: what force, what power required?
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