由不变气源来的压力 10 bar ,温度 27 °C 的空气,初速度为 100m/s , 必须流经一喷管才能进入压力保持在 4 bar 的某装置中(背压)。 假设喷管内为定熵流动,设空气的气体常数 R g = 0.287kJ/(kg·K) ,比热容 c p = 1.005 kJ/(kg·K ) 。 确定应选择的喷管形状。
【简答题】P assage Two It's never too early or too late for a parent to become a teacher. In this age of teacher accountability, endless school testing, increased pressure and competition, and the proliferation...
【单选题】Section B Directions: In this section, you will hear 3 short passages. At the end of each passage, you will hear some questions. Both the passage and the questions will be spoken only once. After you ...
【单选题】Section B Directions: In this section, you will hear 3 short passages. At the end of each passage, you will hear some questions. Both the passage and the questions will be spoken only once. After you ...