FLEET Velocimetry for Aerodynamics

2022 ◽  
Vol 54 (1) ◽  
pp. 525-553
Author(s):  
Paul M. Danehy ◽  
Ross A. Burns ◽  
Daniel T. Reese ◽  
Jonathan E. Retter ◽  
Sean P. Kearney
Keyword(s):  
High Speed ◽  
Gaseous Medium ◽  
Local Heating ◽  
Molecular Tagging Velocimetry ◽  
Molecular Tagging ◽  
Acoustic Disturbances ◽  
Laser Spark ◽  
Ground Test ◽  
Test Flow ◽  
Selection Of

Long-lasting emission from femtosecond excitation of nitrogen-based flows shows promise as a useful mechanism for a molecular tagging velocimetry instrument. The technique, known as femtosecond laser electronic excitation tagging (FLEET), was invented at Princeton a decade ago and has quickly been adopted and used in a variety of high-speed ground test flow facilities. The short temporal scales offered by femtosecond amplifiers permit nonresonant multiphoton excitation, dissociation, and weak ionization of a gaseous medium near the beam's focus without the generation of a laser spark observed with nanosecond systems. Gated, intensified imaging of the resulting emission enables the tracking of tagged molecules, thereby measuring one to three components of velocity. Effects of local heating and acoustic disturbances can be mitigated with the selection of a shorter-wavelength excitation source. This review surveys the development of FLEET over the decade since its inception, as it has been implemented in several test facilities to make accurate, precise, and seedless velocimetry measurements for studying complex high-speed flows.

Selection of the Optimal Type of Bored-Injection Piles Strengthening of Weak Bases of High-Speed Railway Lines

2019 ◽  
pp. 40-44
Author(s):  
N.S. SOKOLOV ◽  
◽  
S.S. VIKTOROVA ◽  
I.P. FEDOSEEVA ◽  
G.M. SMIRNOVA ◽  
...  
Keyword(s):  
High Speed ◽  
High Speed Railway ◽  
Weak Bases ◽  
Selection Of ◽  
Optimal Type

scholarly journals Photoisomeric molecular tagging velocimetry with CCVJ

2021 ◽  
Vol 6 (4) ◽  
Author(s):  
Markus J. Schmidt ◽  
Benno Käslin ◽  
Thomas Rösgen
Keyword(s):  
Molecular Tagging Velocimetry ◽  
Molecular Tagging

scholarly journals Cavitation clusters in lipid systems – surface effects, local heating and streamer formation

2017 ◽  
Vol 19 (9) ◽  
pp. 6785-6791 ◽  
Author(s):  
P. R. Birkin ◽  
T. M. Foley ◽  
T. T. Truscott ◽  
A. Merritt ◽  
S. Martini
Keyword(s):  
Sunflower Oil ◽  
High Speed ◽  
Local Heating ◽  
Surface Effects ◽  
Heating Effects

Cavitation clusters in lipid materials (specifically sunflower oil): high-speed streamers and local heating effects.

Current Design Activities on British Railways

1969 ◽  
Vol 184 (4) ◽  
pp. 5-14
Author(s):  
J. F. Thring
Keyword(s):  
High Speed ◽  
Design Review ◽  
New Developments ◽  
Maintenance Costs ◽  
Current Design ◽  
Design Activities ◽  
Selection Of ◽  
Freight Vehicles

With the identification of profitable freight areas and the selection of growth traffics for development has come the need to review in detail the running gear and, in particular, the suspensions of both 4-wheeled and bogie vehicles. This design review has been aimed at ensuring a high-speed capability for all new freight vehicles coupled with safety at all times, low maintenance costs, and maximum availability. After reviewing traditional suspensions, in wide use, with reference to their known strengths and weaknesses, the paper discusses in some detail the philosophy now being applied in B.R. design offices to new freight running gear, for both 4-wheeled and bogie vehicles, to ensure satisfactory achievement of technical objectives. Examples of new developments are provided, together with comments on progress to date.

Comparative Evaluation of MoS2 and WS2 as Powder Lubricants in High Speed, Multi-Pad Journal Bearings

1999 ◽  
Vol 121 (3) ◽  
pp. 625-630 ◽  
Author(s):  
C. Fred Higgs ◽  
Crystal A. Heshmat ◽  
Hooshang Heshmat
Keyword(s):  
Comparative Evaluation ◽  
High Speed ◽  
Solid Lubricants ◽  
Extreme Environment ◽  
Journal Bearings ◽  
Lubricating Film ◽  
Constant Friction ◽  
Traction Coefficient ◽  
Limiting Value ◽  
Selection Of

As part of a program to develop solid/powder-lubricated journal bearings, a comparative evaluation has been performed to aid in determining whether MoS2 and WS2 powder are suitable lubricants for high-speed, extreme-environment multi-pad journal bearings. Plots of traction coefficients, friction, frictional power loss, and bearing pad temperature are presented as a means for comparing various powder lubricants. This paper primarily focuses on experiments carried out on a three-pad journal bearing and a disk-on-disk tribometer. Results showed that MoS2 traction curves resemble that of SAE 10 synthetic oil. Unlike liquid lubricants, powder films have a limiting shear strength property. Once the powder reaches this limiting value, the maximum traction coefficient is limited and the powder essentially shears along sliding walls. Experimental traction data shows evidence of this property in various powders. The thermal performance of the bearing was evaluated at speeds up to 30,000 rpm and loads up to 236 N. Although WS2 displayed constant friction coefficient and low temperature with increasing dimensionless load, MoS2 exhibited frictional behavior resembling that of a hydrodynamic lubricating film. In this paper, an attempt has been made to provide a criterion for the selection of solid lubricants for use in those tribosystems that may be operated in a high speed/load regime (i.e., high strain rates) as an alternative yard stick to conventional comparative approaches.

Quantitative NO2 molecular tagging velocimetry at 500 kHz frame rate

2010 ◽  
Vol 97 (22) ◽  
pp. 221103 ◽  
Author(s):  
Naibo Jiang ◽  
Munetake Nishihara ◽  
Walter R. Lempert
Keyword(s):  
Frame Rate ◽  
Molecular Tagging Velocimetry ◽  
Molecular Tagging
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