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Mechanical Engineering
Two systems have the following equations of state, where R is the gas constant per mole. The mole numbers are N1 = 3 and N2 = 5. The initial temperatures are T1 = 175 K and T2 = 400 K. What is the temperature once equilibrium is reached (in Kelvin)?
Mechanical Engineering
Two systems have the following equations of state and are contained in a closed cylinder, separated by a fixed, adiabatic and impermeable piston. N1 = 2 and N2 = 1.5 moles. The initial temperatures are T1 = 175 K and T2 = 400 K. The total volume is 0.025 m3. The piston is allowed to move and heat transfer is allowed across the piston. Determine the final temperature of the system (in Kelvin).
Mechanical Engineering
A compressor of 25 kg is mounted on isolator as shown in the figure.
The isolator is idealized by a spring and a damper of damping ration đ= 0.3 . it is found that the compressor suffers from vibration due to unbalance of 0.001 sin50t. also, it is found that all the maximum impressed force is transmitted to the floor. What will be the TR and the maximum Ft  to the floor when the excitation force becomes 0.005sinwt ?
Mechanical Engineering
Linear plate elements and linear solid elements can easily be used in the same mode true or false
Mechanical Engineering
A hydro-electric plant is planned for a site where the available head is 286 m with an
average flow of 42 m3/s.
1.1 What is the available hydraulic power?
1.2 Assuming an overall efficiency of 88% and a runner rotational speed of 450 rpm,
what is the dimensionless specific speed?
1.3 What kind of turbine is suggested for this application?
In order to predict the operational performance of the turbine, it is decided to do tests on
a 1:20 scale model turbine operating under a head of 4 m.
1.3 At what speed is the model expected to run at?
1.4 What flow rate would have to be provided for the model?
1.5 What power is the model expected to deliver?
average flow of 42 m3/s.
1.1 What is the available hydraulic power?
1.2 Assuming an overall efficiency of 88% and a runner rotational speed of 450 rpm,
what is the dimensionless specific speed?
1.3 What kind of turbine is suggested for this application?
In order to predict the operational performance of the turbine, it is decided to do tests on
a 1:20 scale model turbine operating under a head of 4 m.
1.3 At what speed is the model expected to run at?
1.4 What flow rate would have to be provided for the model?
1.5 What power is the model expected to deliver?
Mechanical Engineering
The suction lift of a double acting reciprocating pump is 3.6m, the suction pipe length is 5m of
110 mm diameter tubing with f=0.01(Darcy). The cylinder diameter is 160mm and the piston
stroke is 400mm. Assume simple harmonic motion is considered. The vapour pressure is 2.4m
(absolute) and atmospheric pressure is 10.3m. (Hint: Consider at start of stroke)
1.1. Sketch the indicator diagrams to aid you in your calculations.
1.2. Determine the maximum speeds at it can be run under the following conditions:
(a) No air vessel on the suction side. (Ignore friction for (a))
(b) A large air vessel on the suction side close to the pump.
110 mm diameter tubing with f=0.01(Darcy). The cylinder diameter is 160mm and the piston
stroke is 400mm. Assume simple harmonic motion is considered. The vapour pressure is 2.4m
(absolute) and atmospheric pressure is 10.3m. (Hint: Consider at start of stroke)
1.1. Sketch the indicator diagrams to aid you in your calculations.
1.2. Determine the maximum speeds at it can be run under the following conditions:
(a) No air vessel on the suction side. (Ignore friction for (a))
(b) A large air vessel on the suction side close to the pump.
Mechanical Engineering
(c) In order to avoid excessively high stress in the pipeline during valve closure, it is proposed that the time to fully close the valve is not shorter than 15 s. Is this a safe closure time given that the maximum allowable hoop stress in the pipe is 110 MPa? Use a steady discharge of 15 m3 /s if you were not successful with part (a). (Aide mem: hoop stress, ĎH= pd/2t , where p,d,t are pipe pressure, diameter and wall thickness respectively.)
Mechanical Engineering
c) A 50 mm-diameter propeller was installed in a 150 mm-diameter water pipe and the propeller speed was measured for a range of water discharge in the pipe. The water had a density and dynamic viscosity of 1000 kg/m3 and 0.00112 Ns/m2 respectively. The measured results were as follows:
Q (litres/s): 12 28 45 63 95 120 160 180
N (rps): 5 10 15 20 30 40 60 80
Plot the dependence of propeller coefficient against propeller Reynolds number. A geometrically similar propeller with diameter 100 mm was installed in a 300 mm-diameter pipe conveying oil with density 800 kg/m3 and dynamic viscosity 0.007 Ns/m2 . Estimate the discharge in the oil pipe for measured propeller speeds of 40 rps and 90 rps.
Q (litres/s): 12 28 45 63 95 120 160 180
N (rps): 5 10 15 20 30 40 60 80
Plot the dependence of propeller coefficient against propeller Reynolds number. A geometrically similar propeller with diameter 100 mm was installed in a 300 mm-diameter pipe conveying oil with density 800 kg/m3 and dynamic viscosity 0.007 Ns/m2 . Estimate the discharge in the oil pipe for measured propeller speeds of 40 rps and 90 rps.
Mechanical Engineering
The intensity distribution of solar radiation peaks at a wavelength of approximately 500 nm. Assuming the Sun radiates like a black body, calculate the flux of photons leaving the sun in W/m2.
Mechanical Engineering
Consider the same plate as in the previous question: a square plate of L=1
m side attached to a torsionnal spring of stiffness 10Nm/rad. The mass of the plate is M=1
Kg. Now the air flow is coming from the left at 10m/s. What is the eigenfrequency (Hz) of this oscillator?
