Amodel test of a tractor-trailer rig is performed in a wind tunnel. the drag force, fd, is found to depend on the frontal area, a, wind speed, v, air density, r, and air viscosity, µ. the model scale is 1: 4 (e. g., 1 m in the model is equivalent to 4 m in the prototype), frontal area of the model is a = 0.625 m2 . a. obtain a set of dimensionless parameters suitable to characterize the model test results

Explain the difference laminar and turbulent flow. explain it with the shear stress and the velocity profiles.

Manometers are good examples of measuring instruments, nowadays they are not as common as before. a)-capacitive probe gauges b)-gravitational gauges deformation ) gauges d)-digital gauges

Refrigerant-134a enters the compressor of a refrigerator as superheated vapor at 0.14 mpa and -10°c at a rate of 0.05 ka/s and leaves at 0.8 mpa and 50°c. the refrigerant is cooied in the condenser to 0.72 mpa and 26'c. it is then throttled to 0.15 mpa. sketch the t-s diagram for the system and evaluate: 6) the rate of heat removai from the refrigerated space (kw), it) the power input to the compressor (kw), ii) the isentropic efficiency of the compressor (%), and iv) the cop of the refrigerator.