Đang chuẩn bị liên kết để tải về tài liệu:
HVAC Systems Design Handbook part 16

Fluid mechanics is a fundamental branch of civil, chemical, and mechanical engineering which deals with the behavior of liquids and gases, particularly while flowing. This chapter provides a brief review of the vocabulary and fundamental equations of fluid mechanics, and reminds the HVAC designer of the scientific principles underlying much of the day-to-day applied science calculations. See Ref. 1 or a fluid mechanics text for additional detail. | Source HVAC Systems Design Handbook Chapter 16 Engineering Fundamentals Part 1 Fluid Mechanics 16.1 Introduction Fluid mechanics is a fundamental branch of civil chemical and mechanical engineering which deals with the behavior of liquids and gases particularly while flowing. This chapter provides a brief review of the vocabulary and fundamental equations of fluid mechanics and reminds the HVAC designer of the scientific principles underlying much of the day-to-day applied science calculations. See Ref. 1 or a fluid mechanics text for additional detail. 16.2 Terms in Fluid Mechanics Many words are used in fluid mechanics which carry over into thermodynamics and heat transfer. A few of the fundamental terms are defined here for review. Fluid A liquid or a gas a material without defined form which adapts to the shape of its container. Liquids are essentially incompressible fluids. Gases are compressible. Newtonian fluids are those which deform with a constant rate of shear. Water and air are newtonian fluids. Nonnewtonian fluids are those which deform at one rate of shear to a point and then deform at a different rate. Blood and catsup are nonnewtonian fluids. Density p Mass per unit volume lbm ft3. 447 Downloaded from Digital Engineering Library @ McGraw-Hill www.digitalengineeringlibrary.com Copyright 2004 The McGraw-Hill Companies. All rights reserved. Any use is subject to the Terms of Use as given at the website. Engineering Fundamentals Part 1 448 Chapter Sixteen Viscosity p Resistance to shear force time length 2. Pressure P Force per unit area. Velocity V Distance per unit time ft min ft s. Laminar flow Particles slide smoothly along lines parallel to the wall. Resistance to flow is proportional to the square of the velocity. Turbulent flow There are random local disturbances in the fluid flow pattern about a mean or average fluid velocity. Resistance to flow is proportional to the square of the velocity. Reynolds number Re A dimensionless number relating .