How should the friction coefficient and drag coefficient be understood in the question?
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The friction coefficient and the drag coefficient have different meanings, and sometimes they are also traps in questions. But it was found that the level of rigor in formulating some questions varies. What should one do when encountering this situation? For example, in the question below, if one focuses on the concepts, the answer should be A. But if 0.03 is interpreted as the friction coefficient, the result will be B. What should sailors do in such situations? As shown in the figure from 2011, in the parallel pipeline system, the length of branch AE2B is 45 m, while the length of branch AE1B is 5 m. The inner diameter of both pipes is 80 mm, and the friction coefficient for straight sections is 0.03 for each ； Each of the two branches has 1 heat exchanger, and the local resistance coefficient of each heat exchanger is 3. Then, when the valves on both branches are fully open, what is the flow ratio between the two branches? Note: The length of the branch pipe given is the equivalent length including fittings and valves. A、1 B、2 C、3 D、4
In my understanding, the friction coefficient is used for calculating the resistance in straight pipes, while another coefficient is used for calculating local resistance
In my understanding, the resistance coefficient for straight pipes is the friction coefficient, while for local resistance, it is the local resistance coefficient
As noted in the remarks, the length of the branch pipe provided includes the equivalent lengths of the fittings and valves, so it is possible to use the resistance coefficient for calculation; it’s the same approach.
The term \"friction coefficient of straight pipes\"... in the past, the \"friction coefficient along the flow path\" was also used. In textbooks, for clear distinction, λ is referred to as the Moody friction factor (with the Fanning friction factor being the corresponding one). K or ξ are generally referred to as local resistance coefficients. There is a reasonable range of flow velocities for K or ξ=λ(L/D), with λ generally being small, on the order of 0.02~0.04. The K value is generally high, for example, values such as 0.5 or 1 when connecting pipes to equipment. In this question, seeing the value of 0.03 allows us to determine that it refers to λ