Handbook of Compressible Aerodynamics

Chapter 16

Application of the Shock Wave Theory to Supersonic Air Intakes

16.1. The role of air intake

Air intakes for supersonic aircraft presents an excellent example for the application of the theory of shock waves in steady flow. This chapter describes the operation of such devices given that it is only an introduction to the aerodynamics of air intakes whose design has many aspects that will not be mentioned here. We know that the propulsion of aircraft is provided by the so-called propulsion nacelle, or more simply the nacelle, which brings together the various elements contributing to the propulsion (see section 5.2), namely:

– the air intake, capturing air to feed the engine;

– the engine that can be a turbojet, a ramjet, or even a scramjet engine for air breathing hypersonic vehicles;

– a possible reheat duct or afterburner, where kerosene is burnt downstream of the engine in order to provide extra thrust; and

– the exhaust nozzle whose aerodynamics is presented in Chapter 10.

The engines of current airliners additionally have a fan, arranged in front of the compressor and drawing an airflow that does not cross the compressor–turbine set. The operation of the fan is characterized by the bypass ratio, a ratio of the total drawn airflow and the airflow through the compressor. This bypass ratio is around 10 for modern engines. Engines for combat aircraft and missiles have no fan: it is this type of engine that we will consider here.

By convention, we consider the following ...