Military Aircraft Intake Design

This extended section of the book can be found on the Web site www. cambridge .org/Kundu and discusses the important consideration for typical military aircraft intake design involving supersonic intakes. The associated figure is Figure 10.25.

Figure 10.25. Types of ideal supersonic intake demand conditions [21]

10.9 Exhaust Nozzle and Thrust Reverser

The thrust reverser (TR) is part of an exhaust nozzle and both are addressed in this section; an empirical sizing method for a nozzle is discussed but not the size and

design of the TR, which is a separate technology. Before explaining exhaust nozzles, it is helpful to understand TRs.

The role of a TR is to retard aircraft speed by applying thrust in the forward direction (i. e., in a reversed application). The rapid retardation by the TR applica­tion reduces the landing-field length. In a civil aircraft application, the TR is applied only on the ground. Because of its severity, certification rules require to either design for deployment in flight (e. g., Concorde) or prevent in-flight deployment. However, the latter is the more common approach. A TR reduces the wheel-brake load so there is less wear and fewer heat hazards. A TR is effective on slippery run­ways (e. g., ice and water) when braking is less effective. A typical benefit of having sufficient stopping distance at landing on an icy runway with TR application is that it reduces the field length by less than half. A midsized jet-transport aircraft stops at about 4,000 ft with a TR or at about 12,000 ft without it. Without a TR, the energy that was depleted to stop the aircraft is absorbed by the wheel brake and aerody­namic drag. Application of the TR also provides additional intake momentum drag (at full throttle), contributing to energy depletion. A TR is useful for an aircraft to go in reverse (e. g., a C17) on the ground for parking, alignments, and so forth – most aircraft with a TR do not use reverse but rather a specialized vehicle that pushes it.

A TR is integrated on the nacelle and it is the responsibility of an aircraft man­ufacturer to design it or it may be subcontracted to specialist organizations devoted to TR design. The next section introduces the TR in detail so that coursework can proceed on the nacelle without undertaking the detailed design.

Leave a reply

You may use these HTML tags and attributes: <a href="" title=""> <abbr title=""> <acronym title=""> <b> <blockquote cite=""> <cite> <code> <del datetime=""> <em> <i> <q cite=""> <s> <strike> <strong>