Optimum fan pressure ratio for bypass engines with separate or mixed exhaust streams

A Guha

Research output: Contribution to journalArticle (Academic Journal)peer-review

54 Citations (Scopus)

Abstract

The optimum fan pressure ratio is determined both numerically and analytically for separate-stream as well as mixed-stream bypass engines. The results are applicable to civil and military engines. The optimumfan pressure ratio is shown to be predominantly a function of the speciŽ c thrust and a weak function of the bypass ratio. Two simple, explicit equations, one for each type of engine, have been derived that specify the optimum fan pressure ratio. The predictions compare very well against numerical optimization performed by a specialist computer package employing iterative and advanced search techniques and real gas properties. The analytical relations accelerate the optimization process and offer physical insight. It has been shown that the optimum fan pressure ratio achieves the conditionVjc /Vjh = ´KE in a separate-streamengine and the conditionV163/V63 ¼ ´KE in a mixedstream engine. The condition V163 /V63 ¼ ´KE applies even under situations when signiŽ cant departures from the normally assumed condition p016/p06 ¼ 1 can occur.
Translated title of the contributionOptimum fan pressure ratio for bypass engines with separate or mixed exhaust streams
Original languageEnglish
Pages (from-to)1117 - 1122
Number of pages6
JournalJournal of Propulsion and Power
Volume17 (5)
Publication statusPublished - Sep 2001

Bibliographical note

Publisher: American Institute of Aeronautics and Astronautics

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