Acoustic-vortex interaction in reacting wakes near the global hydrodynamic stability limit

2016 ◽  
Vol 140 (4) ◽  
pp. 3261-3261
Author(s):  
Benjamin Emerson ◽  
Tim Lieuwen
Keyword(s):  
Hydrodynamic Stability ◽  
Stability Limit ◽  
Vortex Interaction

The effect of pressure on the hydrodynamic stability limit of premixed flames

2020 ◽  
Author(s):  
Antonio Attili ◽  
Rachele Lamioni ◽  
Lukas Berger ◽  
Konstantin Kleinheinz ◽  
Pasquale E. Lapenna ◽  
...  
Keyword(s):  
Hydrodynamic Stability ◽  
Premixed Flames ◽  
Stability Limit ◽  
Effect Of Pressure

scholarly journals Single and Multiple Circumferential Casing Groove for Stall Margin Improvement in a Transonic Axial Compressor

2020 ◽  
Author(s):  
A. F. Mustaffa ◽  
V. Kanjirakkad
Keyword(s):  
Axial Compressor ◽  
Stability Limit ◽  
Leading Edge ◽  
Vortex Interaction ◽  
Stall Margin ◽  
Tip Leakage ◽  
Stall Margin Improvement ◽  
Transonic Axial Compressor ◽  
The Stability ◽  
Transonic Rotor

Abstract The stability limit of a tip-stalling axial compressor is sensitive to the magnitude of the near casing blockage. In transonic compressors, the presence of the passage shock could be a major cause for the blockage. Identification and elimination of this blockage could be key to improving the stability limit of the compressor. In this paper, using numerical simulation, the near casing blockage within the transonic rotor, NASA Rotor 37, is quantified using a blockage parameter. For a smooth casing, the blockage at conditions near stall has been found to be maximum at about 20% of the tip axial chord downstream of the tip leading edge. This maximum blockage location is found to be consistent with the location of the passage shock-tip leakage vortex interaction. A datum single casing groove design that minimises the peak blockage is found through an optimisation approach. The stall margin improvement of the datum casing groove is about 0.6% with negligible efficiency penalty. Furthermore, the location of the casing groove is varied upstream and downstream of the datum location. It is shown that the stability limit of the compressor is best improved when the blockage is reduced upstream of the peak blockage location. The paper also discusses the prospects of a multi-groove casing configuration.

scholarly journals SINGLE AND MULTIPLE CIRCUMFERENTIAL CASING GROOVE FOR STALL MARGIN IMPROVEMENT IN A TRANSONIC AXIAL COMPRESSOR

2021 ◽  
pp. 1-22
Author(s):  
Ahmad Fikri Bin Mustaffa ◽  
Vasudevan Kanjirakkad
Keyword(s):  
Axial Compressor ◽  
Stability Limit ◽  
Leading Edge ◽  
Vortex Interaction ◽  
Stall Margin ◽  
Tip Leakage ◽  
Stall Margin Improvement ◽  
Transonic Axial Compressor ◽  
The Stability ◽  
Transonic Rotor

Abstract The stability limit of a tip-stalling axial compressor is sensitive to the magnitude of the near casing blockage. In transonic compressors, the presence of the passage shock could be a major cause for the blockage. Identification and elimination of this blockage could be key to improving the stability limit of the compressor. In this paper, using numerical simulation, the near casing blockage within the transonic rotor, NASA Rotor 37, is quantified using a blockage parameter. For a smooth casing, the blockage at conditions near stall has been found to be maximum at about 20% of the tip axial chord downstream of the tip leading edge. This maximum blockage location is found to be consistent with the location of the passage shock-tip leakage vortex interaction. A datum single casing groove design that minimises the peak blockage is found through an optimisation approach. The stall margin improvement of the datum casing groove is about 0.6% with negligible efficiency penalty. Furthermore, the location of the casing groove is varied upstream and downstream of the datum location. It is shown that the stability limit of the compressor is best improved when the blockage is reduced upstream of the peak blockage location. The paper also discusses the prospects of a multi-groove casing configuration.

Hydrodynamic Stability of Complaint Pipe for Normal Complaince

2015 ◽  
Vol 2 (1) ◽  
pp. 48-60
Author(s):  
S. Anbukumar ◽  
◽  
Munendra Kumar ◽  
Keyword(s):  
Hydrodynamic Stability

Novel method for calculating two-dimensional blade vortex interaction

AIAA Journal ◽  
1997 ◽  
Vol 35 ◽  
pp. 909-912
Author(s):  
Ronald J. Epstein ◽  
John A. Rule ◽  
Donald B. Bliss
Keyword(s):  
Two Dimensional ◽  
Vortex Interaction ◽  
Blade Vortex Interaction ◽  
Novel Method

Normal vortex interaction with a circular cylinder

AIAA Journal ◽  
1999 ◽  
Vol 37 ◽  
pp. 50-57 ◽  
Author(s):  
S. Krishnamoorthy ◽  
A. Gossler ◽  
J. S. Marshall
Keyword(s):  
Circular Cylinder ◽  
Vortex Interaction

Experimental Assessment of the Practical Oxidative Stability of Lithium Thiophosphate Solid Electrolytes

2019 ◽  
Author(s):  
Georg Dewald ◽  
Saneyuki Ohno ◽  
Marvin Kraft ◽  
Raimund Koerver ◽  
Paul Till ◽  
...  
Keyword(s):  
Cyclic Voltammetry ◽  
Solid State ◽  
Oxidative Stability ◽  
Photoelectron Spectroscopy ◽  
Solid Electrolytes ◽  
Stability Limit ◽  
Lithium Ion ◽  
High Energy ◽  
Redox Activity ◽  
Solid State Batteries

<p>All-solid-state batteries are often expected to replace conventional lithium-ion batteries in the future. However, the practical electrochemical and cycling stability of the best-conducting solid electrolytes, i.e. lithium thiophosphates, are still critical issues that prevent long-term stable high-energy cells. In this study, we use <i>stepwise</i><i>cyclic voltammetry </i>to obtain information on the practical oxidative stability limit of Li<sub>10</sub>GeP<sub>2</sub>S<sub>12</sub>, a Li<sub>2</sub>S‑P<sub>2</sub>S<sub>5</sub>glass, as well as the argyrodite Li<sub>6</sub>PS<sub>5</sub>Cl solid electrolytes. We employ indium metal and carbon black as the counter and working electrode, respectively, the latter to increase the interfacial contact area to the electrolyte as compared to the commonly used planar steel electrodes. Using a stepwise increase in the reversal potentials, the onset potential at 25 °C of oxidative decomposition at the electrode-electrolyte interface is identified. X‑ray photoelectron spectroscopy is used to investigate the oxidation of sulfur(-II) in the thiophosphate polyanions to sulfur(0) as the dominant redox process in all electrolytes tested. Our results suggest that after the formation of these decomposition products, significant redox behavior is observed. This explains previously reported redox activity of thiophosphate solid electrolytes, which contributes to the overall cell performance in solid-state batteries. The <i>stepwise cyclic voltammetry</i>approach presented here shows that the practical oxidative stability at 25 °C of thiophosphate solid electrolytes against carbon is kinetically higher than predicted by thermodynamic calculations. The method serves as an efficient guideline for the determination of practical, kinetic stability limits of solid electrolytes. </p>

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