Heat Transfer Questions & Answers  




Here we were doing an order of magnitude analysis. As long as $\delta$ and $\delta_t$ are within the same order of magnitude (and as will be shown later, they are), the analysis is correct. 1 point bonus.




In the question, it says the journal bearing has a diameter of 75 mm. It's not mentioned whether this is the diameter of the shaft or of the casing. This doesn't really matter here because the difference in diameter is quite small. I chose the diameter of the casing ($D_{\rm o}$) to be 75 mm. 1 point bonus.




What is $T_0$ in your second definition of Ec? We need to know how $T_0$ is defined. Write down the definition for $T_0$ and try to to express it as a function of $u_\infty$.




Great! 1 point bonus for bringing this up.



$\pi$ 