Đang chuẩn bị liên kết để tải về tài liệu:
Ebook Introduction fluid mechanics (8th edition): Part 2

(BQ) Part 2 book "Introduction fluid mechanics" has contents: External incompressible viscous flow, fluid machinery, fluid machinery, introduction to compressible flow, compressible flow. | 9 External Incompressible Viscous Flow Part A Boundary Layers 9.1 The Boundary-Layer Concept 9.2 Boundary-Layer Thicknesses 9.3 Laminar Flat-Plate Boundary Layer: Exact Solution (on the Web) 9.4 Momentum Integral Equation 9.5 Use of the Momentum Integral Equation for Flow with Zero Pressure Gradient 9.6 Pressure Gradients in Boundary-Layer Flow Part B Fluid Flow About Immersed Bodies 9.7 Drag 9.8 Lift 9.9 Summary and Useful Equations 421 422 Chapter 9 External Incompressible Viscous Flow Case Study in Energy and the Environment Wind Power: The Magenn Air Rotor System (MARS) In Chapter 8’s Case Study in Energy and the Environment, we looked at an alternative to the threebladed wind turbine farms that are cropping up all over the world. In this Case Study we look at a second unique idea for wind power, the Magenn Air Rotor System (MARS). Magenn Power is a company that’s been in business several decades and that began designing the Magnus Spherical Airship in 1978. The founder of Magenn Power, Fred Ferguson, patented the Magnus Airship in the 1980s. This unique airship generates extra lift due to the Magnus effect. We will discuss the Magnus effect in this chapter, but for now we simply state that the effect is one in which a lift force is generated whenever a sphere or cylinder rotates in a cross flow; the classic example is in golf, where a ball hit with backspin will travel much further due to the lift generated by the spin. The airship was a large spherical envelope filled with helium to achieve static, buoyant lift. It was designed to rotate as it moved so that Magnus lift was generated. With Magnus lift, as we’ll learn in this chapter, the faster the spin or the vehicle’s forward motion, the larger the Magnus lift. The MARS shown in the rendering is a high-altitude lighter-than-air, tethered device that rotates about a horizontal axis in response to wind; it is essentially a horizontal-axis Savonius type of wind turbine (see Figure P9.97 in the problem set).