1 Introduction

Aerodynamics is the branch of fluid mechanics that deals with the determination of the flow past bodies of aeronautical interest. Gravity forces are neglected, and viscosity is regarded as small so that the viscous forces are confined to thin boundary layers (Figure 10.1). The subject is called incompressible aerodynamics if the flow speeds are low enough (Mach number < 0.3) for the compressibility effects to be negligible. At larger Mach numbers the subject is normally called gas dynamics, which deals with flows in which compressibility effects are important. In this chapter we shall study some elementary aspects of incompressible flow around aircraft wing shapes. The blades of turbomachines (such as turbines and compressors) have the same cross section as that of an aircraft wing, so that much of our discussion will also apply to the flow around the blades of a turbomachine.

Because the viscous effects are confined to thin boundary layers, the bulk of the flow is still irrotational. Consequently, a large part of our discussion of irrotational flows presented in Chapter 6 is relevant here. It is assumed that the reader is familiar with that chapter.

2 The Aircraft and Its Controls

Although a book on fluid mechanics is not the proper place for describing an aircraft and its controls, we shall do this here in the hope that the reader will find it interesting. Figure 15.1 shows three views of an aircraft. The bodyof the aircraft, which houses the passengers and...