Infrared Signature of Combat Aircraft Incorporating Weight Penalty due to the Divergent Section of the Convergent-Divergent Nozzle Indian Institute of Technology (IIT) Bombay

Format:

Book

Conference/Event

Author/Creator:

Baranwal, Nidhi, author.

Contributor:

Mahulikar, Shripad P.

Conference Name:

Automotive Technical Papers (2021-01-01 : Warrendale, Pennsylvania, United States)

Language:

English

Physical Description:

1 online resource cm

Place of Publication:

Warrendale, PA SAE International 2021

Summary:

Performance penalties associated with infrared (IR)-signature suppression (IRSS), e.g., increased engine back pressure, weight, drag, cost, and complexity, can shift the engine operating point to higher combustion temperatures. Extra weight degrades aircraft flight performance in terms of reduced range, higher length needed for takeoff, reduced maneuverability, et cetera Lift-induced drag penalty due to increased weight shifts the aircraft gas turbine engine operating point to a higher combustion temperature. But the divergent section of the convergent-divergent (C-D) nozzle gives the extra thrust up to optimal flow expansion, which more than compensates the increased lift-induced drag corresponding to its weight. Thus, for the same thrust, an engine with a C-D nozzle operates at a lower combustion temperature than with a convergent nozzle. This study theoretically addresses the net effect of incorporation of a divergent section (considering its weight penalty) on aircraft performance for two cases: (i) shift in engine operating point to lower combustion temperature, for the same thrust; (ii) fixed engine operating point, with increased thrust. For both cases, the IR-signature in the boresight of the C-D nozzle with increasing divergent-section length up to optimal flow expansion is compared with that of a convergent nozzle in 1.9-2.9 μm (SWIR), 3-5 μm (MWIR), and 8-12 μm (LWIR) bands. It is found that visibility is a more important parameter in the 8-12 μm band, as compared to the 1.9-2.9 μm and 3-5 μm bands

Notes:

Vendor supplied data

Publisher Number:

2021-01-6002

Access Restriction:

Restricted for use by site license