Flow Field Measurements of an Unsteady Reacting Muzzle Exhaust Flow

The events associated with the discharge of a 20-mm caliber weapon have been examined in detail in order to identify and understand important features of the reacting gun muzzle flow field. The diagnostics applied involves shadowgraph and Schlieren photography, invasive pressure probes, spectroscopy for temperature measurements and Laser-Doppler velocimetry for velocity measurements. Emphasis has been on velocity measurements using two setups to determine both the axial and lateral velocity components throughout the muzzle flow field. The data clearly demonstrate the complexity of the processes involved in the unsteady flow expansion of the gun muzzle exhaust flow.

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Flow Field Measurements in a Metal Additively Manufactured Offset Strip Fin Array Using Laser Doppler Velocimetry

Journal of Fluids Engineering ◽

10.1115/1.4049245 ◽

2020 ◽

Author(s):

David Saltzman ◽

Stephen Lynch

Keyword(s):

Surface Roughness ◽

Heat Exchanger ◽

Flow Field ◽

Laser Doppler Velocimetry ◽

Field Measurements ◽

Laser Doppler ◽

Doppler Velocimetry ◽

Pressure Losses ◽

Wide Range ◽

Offset Strip Fin

Abstract Metal additive manufacturing (AM) of heat exchanger enables custom and conformal designs for a wide range of applications. However, one challenge with metal AM is the resultant surface roughness formed when using this process which is non-existent during traditional manufacturing processes. The goal in this study is to explore how this roughness impacts the pressure drop and flow field of a commonly used heat exchanger surface called an offset strip fin (OSF). Two OSF of the same geometry are tested: one with an average fin roughness of 34 µm from metal AM and the other with an average fin roughness 2.5 µm, used as a baseline. The roughness from the metal AM process increased pressure losses and transitioned the flow to turbulent-like behavior at lower Reynolds numbers when compared with the smooth fin. Laser Doppler Velocimetry (LDV) measurements captured the row number in the fin array where transition from laminar to turbulent-like flow occurred. The location of transition from low to high turbulence levels occurred earlier in the fin array as the Reynolds number was increased for the smooth and rough fins. Wake profiles of time-averaged axial velocity were similar between the rough and smooth fins, with the rough fins having higher levels of turbulence intensity and less symmetric wake profiles. Overall, this study indicates that a pressure loss penalty is associated with using metal AM OSF due to the resultant surface roughness and an earlier transition to turbulent-like flow.

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Near-exit flow-field investigation in an inducer including laser-Doppler velocimetry

International Journal of Heat and Fluid Flow ◽

10.1016/0142-727x(93)90044-n ◽

1993 ◽

Vol 14 (1) ◽

pp. 86-93 ◽

Cited By ~ 2

Author(s):

J.H.G. Howard ◽

A. Atif

Keyword(s):

Flow Field ◽

Laser Doppler Velocimetry ◽

Field Investigation ◽

Laser Doppler ◽

Doppler Velocimetry

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ACOUSTIC VELOCITY MEASUREMENTS IN THE AIR BY MEANS OF LASER DOPPLER VELOCIMETRY: DYNAMIC AND FREQUENCY RANGE LIMITATIONS AND SIGNAL PROCESSING IMPROVEMENTS

Journal of Sound and Vibration ◽

10.1006/jsvi.1999.2516 ◽

2000 ◽

Vol 229 (3) ◽

pp. 607-626 ◽

Cited By ~ 26

Author(s):

J.C. VALIÈRE ◽

P. HERZOG ◽

V. VALEAU ◽

G. TOURNOIS

Keyword(s):

Signal Processing ◽

Laser Doppler Velocimetry ◽

Acoustic Velocity ◽

Laser Doppler ◽

Doppler Velocimetry ◽

Frequency Range ◽

Velocity Measurements

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Experimental Investigations of Clocking in a One and a Half Stage Transonic Turbine Using Laser-Doppler-Velocimetry and a Fast Response Aerodynamic Pressure Probe

Volume 6: Turbomachinery, Parts A and B ◽

10.1115/gt2006-90264 ◽

2006 ◽

Author(s):

O. Schennach ◽

J. Woisetschla¨ger ◽

A. Fuchs ◽

E. Go¨ttlich ◽

A. Marn ◽

...

Keyword(s):

Flow Field ◽

Laser Doppler Velocimetry ◽

Fast Response ◽

Laser Doppler ◽

Experimental Investigations ◽

Pressure Probe ◽

Doppler Velocimetry ◽

Flow Angle ◽

Aerodynamic Pressure ◽

Transonic Turbine

The current paper presents experimental clocking investigations of the flow field in midspan in a high-pressure transonic turbine with a downstream vane row (1.5 stage machine). Laser-Doppler-Velocimetry measurements were carried out in order to record rotor phase resolved velocity, flow angle and turbulence distributions upstream and downstream of the second vane row at several different vane-vane positions. Additionally, a fast response aerodynamic pressure probe was used to get the total pressure distribution downstream of the second vane row for the same positions. Altogether, the measurements were performed for ten different 1st vane to 2nd vane positions (clocking positions) for measurements downstream of the 2nd vane row and two different clocking positions for measurements upstream of the 2nd vane row. The paper shows that different clocking positions have a significant influence on the flow field downstream of the 2nd vane row. Furthermore different measurement lines upstream of the 2nd vane row indicate that clocking has nearly no influence on the flow field close to the rotor exit.

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