Упражнение 72. Вставьте необходимые тире, скобки или запятые вместо пробелов и переведите предложения

1. Semi__ open impellers and open impellers rely on the close clearance between impeller and pump casing __ about 0.5 mm__ for their function. 2. Normally a free passage of 80 mm will be sufficient for unscreened sewage in small and medium__ sized pumps. 3. A double__ channel impeller is shown in Figure 23. 4. For heavy__ duty reciprocating engines, three__ layer bearings are common. 5. Copper__ lead alloys containing 20 to 50% lead__ either cast or sintered on a steel back__ provide good fatigue resistance for heavy__ duty main and connecting rod bearings for automotive__ truck__diesel__and aircraft engines. 6. The 10% lead__10% tin leaded bronze has been a traditional selection for bearings in steel mills__ appliances__pumps__ automotive piston pins__ and trunions. 7. Various plastics__ porous bronze and porous iron__ carbon-graphite__ rubber__ and wood are widely used for bearings operating dry or with sparse lubrication. 8. If a single heated element is used within an array of unheated elements__ the resulting heat transfer coefficient is implicitly defined as hadiabatic and should be identified as such. 9. It uses a uniform and constant__temperature substrate __originally__ a tank of warm water__ now a copper block__ covered with a layer of known thermal resistance __originally__ a plate of glass__ now a thin layer of epoxy__. 10. Even highly irregular geometries can be studied with this technique__ if the streamwise extent of the specimen is small and the testing time is short. 11. Sometimes the “effective average heat transfer coefficient” for a system is inferred from the overall behavior of the system__ e.g. __ estimating h from the effectiveness of a heat exchanger. 12. This circuit can be used to predict the temperature distribution within the probe both at steady state and during transients and can be refined__ if needed__by subdividing the resistance and capacitance entities. 13. At 1 m/sec air velocity__ the self-heating error is reduced to between 0.03 and 0.3 ºC. 14. The resistance__temperature characteristic of a probe may drift __i.e., change with time__ while the probe is in service. 15. The principal disadvantages of temperature__sensitive paints and crayons are that they require visual interpretation__ which can be highly subjective__ and they are one__shot, irreversible indicators which respond to the highest temperature encountered during the test cycle.