i need the answers please Mohamed is a member of a sports car group at Bahrain P
ID: 2995054 • Letter: I
Question
i need the answers please
Mohamed is a member of a sports car group at Bahrain Polytechnic and he wants to view a testing of a new car to the Fluid Mechanics laboratory using the wind tunnel. The technician - engineer explained to him that a diffuser is used to slow the air flow and exhaust it. He also mentioned that the velocity at the exit of the diffuser should be less than 2.5m/s for safety considerations. The problem is that the temperature has not been checked and if it is higher than 37o C, it will be harmful to the environment. The technician also informed Mohamed that we know the temperature at diffuser inlet is lOo C, the pressure 85kPa and the inlet diameter is equal to 1.5m. He asked him to explore if the air of the wind tunnel is safe to exhaust after flowing through the diffuser. Proposed steps: Produce a simple schematic of the above lab test. (LOs: 2) (10%) Which assumption(s) you are oblige to do in order to calculate the requested temperature? (LOs: l, 2) (10%) Define or determine the velocity values of the air at the inlet and at the outlet of the diffuser (LOs: 1, 2) (10%) Define or determine the temperature of the air at the inlet and at the outlet of the diffuser. (LOs: 2, 3) (20%) Show if the air is safe to exhaust to the outside environment and give recommendations related to this issue. (LOs: 2, 3) (10%)Explanation / Answer
b)
The air flows adibaticallyy.
c)
Density at inlet rho1 = P1 / (R*T1)
= 85000 / (287*(273+10))
= 1.046 kg/m^3
rho1*A1*V1 = rho2*A2*V2
1.046*(pi/4*1.5^2)*V1 = (P2 / (R*T2))*(pi/4*d2^2)*2.5
2.355*V1 = (100,000 / (287*T2))*d2 ^2 *2.5
V1 = 369.9*d2 ^2 / T2.................1
P1 + 1/2*rho1*V1 ^2 = P2 + 1/2*rho2*V2 ^2
85000 + 1/2*1.046*(369.9*d2 ^2 / T2) ^2 = 100,000 + 1/2*(100,000 / (287*T2))*2.5 ^2...............2
Using eqn 2, if we know d2, we can calculate T2.
Then using eqn 1 and putting d2 and T2, we can find V1.
d)
T2 can be found as shown above.
e)
If T2 > 37 deg C, it is not safe. Otherwise safe.
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