热能与动力工程,专业英语期末考题.doc

选择题： If the system does not exchange energy with surroundings, it is an _________ A open system B closed system C isolated system D ontrol volume 2. If the temperature of the liguid is lower than the saturation emperature for the existing pressure,it is called a_________liquid. A superheated B subcooled C saturation D dry saturated 3. If the efficiency of a real engine is significantly_______ the efficiency of a Carnot engine between the same limits, thenadditional improvements may be possible. A lower than B more than C equal to D greater than 4. The velocity bector of a flow is expressed as V =ax2i+byztj, such a flow is a ____ dimensional flow. A one B two C three D four 5. the critical Reynolds number of a rough-walled pipe is about_______. A 3x106 B 3x105 C 2000 D 1500 6. If _______，the density variations influence the flow and compressibility effects shuld be accounted for;such flows are compressinle flows. A M0.3 B M0.3 C M0.2 D M0.1 7. Any _______effects that may exist are confined to a thin layer,called a boundary layer,that is attached to the boundary ,the velocity in a boundary laryer is always zero at a fixed wall. A shear B gravitational C inertial D viscous 8. The ratio of the heat transfer surface area of a heat exchanger to its volume is called the area densityβ.A heat exchanger with_______is classifiedas being compact. A β700m2/m3 Bβ700m2/m3 Cβ500m2/m3 Dβ1000m2/m3 9. The type of heat exchanger that involves the alternate passage of the hot and clod fluid streams through the same flow area is the _______heat exchanger. A regenerative B compact Cplate and frame Dshell-and -tube 10. Not all the radiation leaving one surface will reach the other surface since electromagnetic radiation travels in straight lines and some will be lost to the surroundings,we introduce _______in net radiant exchange. A reflectivity B em