Lovely Professional University 2009 B.Tech Information Technology Assignment 3- Mechanical Engneering - Question Paper

MEC 251

ASSIGNMENT 3


ques. 1: obtain the acceleration and the vorticity components at a point (1,1,1) for the subsequent flow field:

u = two x2 + three y, v = - two xy + three y2 + three zy, w = - 1.5 z2 + two xz – nine y2z

ques. 2: Water flows through a circular pipe. At 1 section, diameter is 0.3 m, the static pressure is 260 kPa gauge, the velocity is 3m/s and the elevation is 10 m above ground level. The elevation at a part downstream is 0 m, and the pipe diameter is 0.15 m. obtain the gauge pressure at the downstream part. Frictional effect may be neglected. presume density of water to be 999 km/m3

ques. 3: An external mouthpiece converges from the inlet up to the vena contracta to the shape of the jet and then it diverges gradually. The diameter at the vena contracta is 20 mm and the total head over the centre of the mouthpiece is 1.44 m of water above the atmospheric pressure. The head loss in the flow through the converging passage and through the diverging passage may be taken as 1 percent and 5 percent respectively of the total head at the inlet to the mouthpiece. What is the maximum discharge that can be drawn through the outlet and what should be the corresponding diameter at the outlet. presume that the pressure in the system may be permitted to fall to 8m of water beneath the atmospheric pressure head, and the liquid conveyed is water.

ques. 4: compute the work necessary to compress air in an insulated cylinder from a quantity of 6ft3 to a quantity of 1.2ft3. The initial temperature and pressure are 50o F and 30 psia, respectively.

ques. 5: 2 kg of superheated steam at 400oC and 600 kPa is cooled at constant pressure by transferring heat from a cylinder until the steam is completely condensed. The surroundings are at 25o. Determine the net entropy production due to this process.

ques. 6: A diesel cycle, with a compression ratio of 18, operates on air with a low pressure of 200 kPa and a low temperature if 200o C. If the high temperature is limited to 2200 K, determine the thermal efficiency and the MEP. Also compute the efficiency of an Otto cycle operating with the identical compression ratio.

ques. 7: Air enters the compressor of a gas turbine at 100 kPa and 25oC. For a pressure ratio of five and a maximum temperature if 850o C, determine the back work ratio and the thermal efficiency for this Brayton cycle, assuming that compressor and the gas turbine both having efficiency of 75%

Earning:   Approval pending.