传热学上海交通大学Recall Flui Mechanics.pptVIP

HEAT TRANSFER What is Convective Heat Transfer? You have already experienced it. Difficulty lies in generalizing our experience; filtering it down to a few laws; learning how to apply these laws to systems we engineers design and use. Here is what I want you to do: If a person masters the fundamentals of his subject and has learned to think and work independently, he will surely find his way and besides will better be able to adapt himself to progress and changes than the person whose training principally consists in the acquiring of detailed knowledge. – Albert Einstein So, please read ahead and come prepared with good questions for the class. 1. Introduction to DIMENSIONAL ANALYSIS Dimensions Each quantitative aspect provides a number and a unit. For example, The three basic dimensions are L, T, and M. Alternatively, L, T, and F could be used. We can write The notation is used to indicate dimensional equality. Here, The results will be independent of the system of units. This type of analysis is called -----dimensional analysis. 4) Buckingham Pi theorem Here, we use the symbol to represent a dimensionless product. For equation, We can rearrange to, 2. The Navier-Stokes Equations Combine the differential equations of motion, the stress-deformation relationships and the continuity equation. 3. general characteristics of pipe flow 1) Laminar or turbulent flow Osborne Reynolds-------flowrates 3) Fully developed laminar flow 4) Fully developed turbulent flow Transitional flow: 2100Re4000 Turbulent flow: Re4000 Turbulent velocity profile There is no general accurate expression for turbulent velocity profile. # * Heat Transfer Su Yongkang School of Mechanical Engineering Recall: Fluid Mechanics 2)