I just cannot get to the answers to these questions, anyone able to help? I need the working out shown.
QUESTION ONE. - A horizontal pipe contains water at a pressure of 250kPa, flowing with a speed of 2m/s. When the pipe narrows to 50% of its original radius, what is;
a) The Speed of the water?
b) The pressure of the water?
The answers should be:
a) 8 m/s
b) 220 kPA
QUESTION 2.
What is the lift force due to Bernoulli's Principle on a planes wing of area of 80m^2 if the air passes over the top of the wing at a speed of 240m/s and under the bottom of the wing at 175m/s? Take the density of air to be 1.3kgm^-3.
Answer should be approximately 1402700 N
Any help would be appreciated so much, thanks in advance.
QUESTION ONE. - A horizontal pipe contains water at a pressure of 250kPa, flowing with a speed of 2m/s. When the pipe narrows to 50% of its original radius, what is;
a) The Speed of the water?
b) The pressure of the water?
The answers should be:
a) 8 m/s
b) 220 kPA
QUESTION 2.
What is the lift force due to Bernoulli's Principle on a planes wing of area of 80m^2 if the air passes over the top of the wing at a speed of 240m/s and under the bottom of the wing at 175m/s? Take the density of air to be 1.3kgm^-3.
Answer should be approximately 1402700 N
Any help would be appreciated so much, thanks in advance.
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(1).
v' = v(A/A')
A = ¼ π D²
v' = v(D/D')²
v' = 2(1/0.5)²
v' = 8 m/s
(2).
P₁ + ρ g h₁ + ½ ρ v₁² = P₂ + ρ g h₂ + ½ ρ v₂²
250 * 1000 + 0 + ½ * 1000 * 2² = P₂ + 0 + ½ * 1000 * 8²
P₂ = 220000 Pa
(2).
P₁ + ρ g h₁ + ½ ρ v₁² = P₂ + ρ g h₂ + ½ ρ v₂²
P₂ - P₁ = ½ ρ v₁² - ½ ρ v₂²
F/A = ½ ρ v₁² - ½ ρ v₂²
F/A = ½ ρ (v₁² - v₂²)
F/80 = ½ (1.3)(240² - 175²)
F = 1402700 Newton
v' = v(A/A')
A = ¼ π D²
v' = v(D/D')²
v' = 2(1/0.5)²
v' = 8 m/s
(2).
P₁ + ρ g h₁ + ½ ρ v₁² = P₂ + ρ g h₂ + ½ ρ v₂²
250 * 1000 + 0 + ½ * 1000 * 2² = P₂ + 0 + ½ * 1000 * 8²
P₂ = 220000 Pa
(2).
P₁ + ρ g h₁ + ½ ρ v₁² = P₂ + ρ g h₂ + ½ ρ v₂²
P₂ - P₁ = ½ ρ v₁² - ½ ρ v₂²
F/A = ½ ρ v₁² - ½ ρ v₂²
F/A = ½ ρ (v₁² - v₂²)
F/80 = ½ (1.3)(240² - 175²)
F = 1402700 Newton
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Sorry, I only know the answer to Q #1-a.
So 'a' has to do with fluid flow continuity. A = area, v = velocity.
A1v1 = A2v2
So the area of a circle is A = pi*r^2
Pi is a constant, so it does not change anything. We can ignore it.
We shall say that the area of the original pipe is 1 for convenience. (Again, ignoring pi)
That means when the pipe narrows, the Area becomes A = (1/2)^2 = (1/4)
When we plug these numbers into the fluid flow continuity equation, we get:
2m/s * 1 m^2 = v2 * (1/4)
2 m^3/s = v2 * (1/4)m^2
-multiply by 4/m^2
8 m/s = v2
v = 8m/s
And there we go.
Sorry I can't help with more of it. I can't remember any pressure equations at the moment.
So 'a' has to do with fluid flow continuity. A = area, v = velocity.
A1v1 = A2v2
So the area of a circle is A = pi*r^2
Pi is a constant, so it does not change anything. We can ignore it.
We shall say that the area of the original pipe is 1 for convenience. (Again, ignoring pi)
That means when the pipe narrows, the Area becomes A = (1/2)^2 = (1/4)
When we plug these numbers into the fluid flow continuity equation, we get:
2m/s * 1 m^2 = v2 * (1/4)
2 m^3/s = v2 * (1/4)m^2
-multiply by 4/m^2
8 m/s = v2
v = 8m/s
And there we go.
Sorry I can't help with more of it. I can't remember any pressure equations at the moment.
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1a) By conservation of volume flow-rate .. A1.v1 = A2.v2
v2 = A1.v1 / A2 = r1².v1 / r2² .. .. π.r1² x 2.0m/s / π(0.50r1)²
v2 = 2 / 0.5² .. .. ►v2 = 8.0 m/s
1b) Using .. ∆P = ½ρ (v1² - v2²)
∆P = ½.1000 kg/m³(2² - 8²) = 500 x -60
∆P = -30000 Pa .. (30 KPa)
P2 = 250 KPa - 30 KPa .. .. .. ►P2 = 220 KPa
2) Using .. ∆P = ½ρ (v1² - v2²)
∆P = ½.1.3 (240² - 175²) = 17534 Pa .. (N/m²)
Lift force .. F = ∆P x A .. .. 17534 N/m² x 80 m² .. .. F = 1.403^6 N
v2 = A1.v1 / A2 = r1².v1 / r2² .. .. π.r1² x 2.0m/s / π(0.50r1)²
v2 = 2 / 0.5² .. .. ►v2 = 8.0 m/s
1b) Using .. ∆P = ½ρ (v1² - v2²)
∆P = ½.1000 kg/m³(2² - 8²) = 500 x -60
∆P = -30000 Pa .. (30 KPa)
P2 = 250 KPa - 30 KPa .. .. .. ►P2 = 220 KPa
2) Using .. ∆P = ½ρ (v1² - v2²)
∆P = ½.1.3 (240² - 175²) = 17534 Pa .. (N/m²)
Lift force .. F = ∆P x A .. .. 17534 N/m² x 80 m² .. .. F = 1.403^6 N