A two-dimensional wedge with an included angle of 10◦(i. e the wedge semi-angle is5◦) is placed in a wind tunnel which has parallel walls. If the Mach number in thefreestream ahead of the wedge is 2.5, and if the center-line of the wedge is inclinedat an angle of 4◦to the direction of the air flow, find the Mach numbers upstreamand downstream of the oblique shock waves after they are reflected off the upperand lower walls of the tunnel. Also sketch the flow pattern marking the angles thewaves make to the tunnel walls.

Air is to be cooled in the evaporator section of a refrigerator by passing it over a bank of 0.8-cm-outer-diameter and 0.4-m-long tubes inside which the refrigerant is evaporating at -20°c. air approaches the tube bank in the normal direction at 0°c and 1 atm with a mean velocity of 4 m/s. the tubes are arranged in-line with longitudinal and transverse pitches of sl- st 1.5 cm. there are 30 rows in the flow direction with 15 tubes in each row. determine (a) the refrigeration capacity of this system and (b) pressure drop across the tube bank. evaluate the air properties at an assumed mean temperature of -5°c and 1 atm. is this a good assumption?