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Coefficient-Preservation Analysis of Offset Double-Serpentine Exhaust Nozzles

Jawad Javed1, Maria Jawad1
1IU International University of Applied Sciences

Abstract

However, offset double-serpentine exhaust nozzles can manipulate the exhaust flow path within restricted propulsion systems, while the aerodynamic quality of such designs cannot be assessed by any coefficient alone. The key issue is the identification of the particular member of the 27-run, four-factor, three-level nozzle design array that maintains the pressure recovery coefficient, discharge coefficient, and axial thrust coefficient at once, and what particular geometric distributions form the limit for the maintenance of the trio of the coefficients. First, the three coefficients of the array will be converted into non-dimensional retention levels of these coefficients with respect to the range between the minimum and maximum levels of the coefficients recorded within L27 table. Next, coefficient preservation index (CPI), lower-tail retention value, response-spread penalty, factor-level contrast, and leave-one-response rank mobility are computed for each configuration. The output is very selective – only configurations 3, 5, and 9 fulfill the conditions CPI \(\geq 0.90\) and lower-tail retention \(\geq 0.85\). Configuration 3 is the single nozzle with complete retention of all the three coefficients, while configurations 5 and 9 provide high triad retention with minimal coefficient imbalance. The factor-level contrasts identify DCV2 and DCS as the controlling factors with the mean CPI level of 0.420 and 0.353 correspondingly. The first vertical distribution (DCV1) is very flat, thus confirming the less significant role of the upstream vertical redistribution against the downstream turning placement.

Keywords: double-serpentine nozzle; exhaust integration; coefficient preservation; L27 orthogonal array; pressure recovery; discharge coefficient; axial thrust coefficient
Citation
Jawad Javed, Maria Jawad. Coefficient-Preservation Analysis of Offset Double-Serpentine Exhaust Nozzles[J], TK Techforum Journal (ThyssenKrupp Techforum), Volume 2023 (3). 35-52.

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Khalid Alghanim1
1Mechanical Engineering Department, Kuwait University, P. O. Box: 5969, Safat, 13060, Kuwait
Joseph Bentsman1
1Department of Mechanical Science and Engineering, University of Illinois at Urbana-Champaign, Urbana, IL, USA