Section outline

    • Why is an understanding of fluid mechanics necessary?

      Wind and water turbines convert energy in a fluid (namely moving masses of air or water) into mechanical energy. To understand and analyse the behaviour of such turbines it is necessary to have a grasp of basic fluid mechanics.

      The operation of wind turbines is based on the lift and drag produced by airfoils. To understand the behaviour of wind turbines it is essential to understand the concepts of laminar and turbulent flow.

      Study tips

      This unit consists of a series of compact study notes and self-test questions. You are recommended to study the unit in the following sequence:

        1. Tackle the pre-test questions, where available, to gauge your prior knowledge. This will indicate whether you need to concentrate on a particular unit.
        2. From the "Syllabus" page, work through the study notes sequentially. Make sure that you understand any worked examples.
        3. Where available, you may wish to tackle the self-test questions as they occur in the sequence. If you encounter difficulties, return to the study notes and focus on the relevant topics before re-visiting the self-test. 

      Objectives

      After completing this topic, you should understand:

        • The basic aspects of the nature and properties of fluids.
        • Hydrostatic forces on surfaces.
        • Fluid dynamics: the Continuity, Bernoulli and Momentum equations.
        • Laminar and turbulent flow and boundary layers.



        • Define the nature of fluid.
        • Show where fluid mechanics concepts are common with those of solid mechanics and indicate some fundamental areas of difference.
        • Introduce viscosity.
        • Define the appropriate physical properties and show how these allow differentiation between solids and fluids as well as between liquids and gases.


        • Introduce the concept of pressure; Prove it has a unique value at any particular elevation;
        • Show how it varies with depth according to the hydrostatic equation and
        • Show how pressure can be expressed in terms of head of fluid.

      This understanding of pressure will then be used to demonstrate methods of pressure measurement that will be useful later with fluid in motion and also to analyse the forces on submerges surface/structures.



    • At the end of this section you should understand the concepts of:

        • Introduce concepts necessary to analyse fluids in motion.


    • Introducing Reynolds number and the concepts of laminar and turbulent flow