Numerical modelling of explosively formed projectiles compared with experiments and results of a numerical sensitivity study

Numerical modelling of aero engine combustors under relight conditions is a matter of continuously increasing importance due to the demanding engine certification regulations. In order to reduce the complexity and the cost of the numerical modelling, common practice is to replace the atomizer’s swirlers with velocity profiles boundary conditions, very often scaled down from nominal operating conditions assuming similarity of the swirler flowfield. The current numerical study focuses on the flowfield characteristics of an axially swirled atomizer operating within a windmilling engine environment. The scalability of the velocity profile from higher power settings is examined. Observations on the performance of the axial swirler under relight conditions are also made. Experimental data was used as a validation platform for the numerical solver, after a grid sensitivity study and a turbulence model selection process. Boundary conditions for simulating the windmilling environment were extracted from experimental work. The swirler axial and tangential velocity profiles were normalised using the swirler inlet velocity. Results showed that both profiles are only scalable for windmilling conditions of high flight Mach number (≥ 0.5). At low flight Mach numbers, the actual profile had a lower velocity than that predicted through scaling. The swirl number was found to deteriorate significantly with the flight velocity following a linear trend, reducing significantly the expected flame quality. As a consequence the burner is forced to operate at the edge of its stability loop with low certainty regarding its successful relight.

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Influence of depth, temperature, and structure of a crustal heat source on the geothermal reservoirs of Tuscany: numerical modelling and sensitivity study

Geothermal Energy ◽

10.1186/s40517-016-0047-7 ◽

2016 ◽

Vol 4 (1) ◽

Cited By ~ 10

Author(s):

Anozie Ebigbo ◽

Jan Niederau ◽

Gabriele Marquart ◽

Ivano Dini ◽

Martin Thorwart ◽

...

Keyword(s):

Numerical Modelling ◽

Heat Source ◽

Sensitivity Study ◽

Geothermal Reservoirs

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Race Difference in Auditory Sensitivity

Journal of Speech and Hearing Research ◽

10.1044/jshr.0704.389 ◽

1964 ◽

Vol 7 (4) ◽

pp. 389-393 ◽

Cited By ~ 3

Author(s):

David C. Shepherd ◽

Robert Goldstein ◽

Benjamin Rosenblüt

Keyword(s):

White Women ◽

White Men ◽

Sensitivity Study ◽

Auditory Sensitivity ◽

Race Difference ◽

Men And Women ◽

Auditory Thresholds ◽

Békésy Audiometry ◽

Method Of Adjustment ◽

Better Than

Two separate studies investigated race and sex differences in normal auditory sensitivity. Study I measured thresholds at 500, 1000, and 2000 cps of 23 white men, 26 white women, 21 negro men, and 24 negro women using the method of limits. In Study II thresholds of 10 white men, 10 white women, 10 negro men, and 10 negro women were measured at 1000 cps using four different stimulus conditions and the method of adjustment by means of Bekesy audiometry. Results indicated that the white men and women in Study I heard significantly better than their negro counterparts at 1000 and 2000 cps. There were no significant differences between the average thresholds measured at 1000 cps of the white and negro men in Study II. White women produced better auditory thresholds with three stimulus conditions and significantly more sensitive thresholds with the slow pulsed stimulus than did the negro women in Study II.

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