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

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.

Flow Field Measurements of an Unsteady Reacting Muzzle Exhaust Flow

1983 ◽  
Vol 105 (4) ◽  
pp. 884-888 ◽  
Author(s):  
G. Klingenberg ◽  
H. Mach ◽  
G. Smeets
Keyword(s):  
Flow Field ◽  
Unsteady Flow ◽  
Laser Doppler Velocimetry ◽  
Field Measurements ◽  
Laser Doppler ◽  
Temperature Measurements ◽  
Doppler Velocimetry ◽  
Velocity Measurements ◽  
Lateral Velocity ◽  
Schlieren Photography

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.

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

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.

Examination of a Swimming Dummy’s Flow Field Using Laser Doppler Velocimetry

2006 ◽  
pp. 75-80 ◽  
Author(s):  
Kerstin Witte ◽  
Bernd Wunderlich ◽  
Nils Betzler ◽  
Dominique Thévenin ◽  
Róbert Bordás ◽  
...  
Keyword(s):  
Flow Field ◽  
Laser Doppler Velocimetry ◽  
Laser Doppler ◽  
Doppler Velocimetry

Aspects of Design and Manufacture of a Three-Dimensional Fibre Optic Laser Doppler Probe Head

2013 ◽  
Vol 397-400 ◽  
pp. 103-113 ◽  
Author(s):  
Noor A. Ahmed
Keyword(s):  
Flow Field ◽  
Laser Doppler Velocimetry ◽  
Three Dimensional ◽  
Laser Doppler ◽  
Doppler Velocimetry ◽  
Fibre Optic ◽  
Complex Flow ◽  
Doppler Probe ◽  
Dimensional Measurements ◽  
Probe Head

Laser Doppler Velocimetry is an important flow diagnostic methodology used in modern day fluid flow investigations. The present paper describes the design and manufacturing aspects of a novel fibre optic LASER Doppler probe head intended for three dimensional measurements in a complex flow field. The paper particularly concentrates on the tight tolerances required of the various components associated with the probe head to achieve the desired measurement volume. Keywords: Fibre Optic, Laser Doppler, Velocimetry, three-dimensional, complex flow field

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

2006 ◽  
Vol 129 (2) ◽  
pp. 372-381 ◽  
Author(s):  
O. Schennach ◽  
J. Woisetschläger ◽  
A. Fuchs ◽  
E. Göttlich ◽  
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 first vane to second vane positions (clocking positions) for measurements downstream of the second vane row and two different clocking positions for measurements upstream of the second vane row. The paper shows that different clocking positions have a significant influence on the flow field downstream of the second vane row. Furthermore, different measurement lines upstream of the second vane row indicate that clocking has nearly no influence on the flow field close to the rotor exit.

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