Flow Structures of a Radial-Inlet Swirler

2000 ◽  
Author(s):  
Zhanhua Ma ◽  
Dexin Wang ◽  
San-Mou Jeng ◽  
Michael A. Benjamin
Keyword(s):  
Reynolds Number ◽  
Flow Field ◽  
Laser Doppler Velocimetry ◽  
Strong Influence ◽  
Flow Fields ◽  
Flow Structures ◽  
Doppler Velocimetry ◽  
Swirl Chamber ◽  
Radial Profiles ◽  
Downstream Flow

The upstream and downstream flows of a radial inlet swirler were investigated by using a 2-D Laser Doppler Velocimetry (LDV) probe. The radial profiles of axial and tangential velocities at various axial locations were obtained. The effects of Reynolds Number, swirler exit configuration and combustor outlet condition were examined. The results reveal that the combustor outlet condition has strong influence on the downstream flow field of the swirler. The effect of Reynolds Number depends on the swirler exit configurations. The influence of the convergent configuration from swirl chamber to orifice on the flow fields is very small whereas the influence of the divergence at the swirler exit is significant. The upstream and downstream flows of the radial inlet swirler are of sub-critical nature, thus the swirler exit configuration and combustor outlet condition significantly affect the flow fields.

The Distribution and Stability of Flow in a Rotating Channel

1968 ◽  
Vol 90 (3) ◽  
pp. 229-235 ◽  
Author(s):  
H. S. Fowler
Keyword(s):  
Reynolds Number ◽  
Flow Field ◽  
Centrifugal Compressor ◽  
Channel Wall ◽  
Flow Distribution ◽  
Stability Change ◽  
The Stability ◽  
Downstream Flow ◽  
Adjacent Channels ◽  
Rotating Channel

The importance of flow distribution and stability leaving the impeller of a centrifugal compressor is discussed. Experiments on the flow in converging, parallel, and diffusing channels, representative of sections of impeller channels, are reported and discussed. The convergent or divergent character of the channel appears to have less influence on the flow pattern than on the stability. Change of Reynolds number appears to change the degree of nonuniformity of distribution in the channel, but change of rotation number appears to affect the distribution of the nonuniformity more. It appears that the influence of adjacent channels, and of the downstream flow-field in general, has a large effect on the flow within the rotating channel, particularly as regards detachment from the suction channel wall. “No man is an island unto himself,” and no element in an aerodynamic system can be divorced from its upstream or downstream neighbors.

Fluid Dynamic Characteristics of the Flow Over an Array of Large Roughness Elements

1991 ◽  
Vol 113 (4) ◽  
pp. 367-373 ◽  
Author(s):  
S. V. Garimella ◽  
P. A. Eibeck
Keyword(s):  
Reynolds Number ◽  
Laser Doppler Velocimetry ◽  
Fluid Dynamic ◽  
Water Channel ◽  
Leading Edge ◽  
Channel Height ◽  
Doppler Velocimetry ◽  
Reattachment Length ◽  
Roughness Elements ◽  
Large Roughness

Flow visualization and measurements of velocity and turbulence intensity using laser Doppler velocimetry are used to investigate separation and reattachment processes in the flow over an array of protruding elements mounted on the bottom wall of a rectangular water channel. The concept of an array shear layer is introduced to demarcate the region of influence over which the resistance of the array retards the flow. Flow separation at the leading edge of the elements is documented. The confined or interacting nature of the flow in the cavities between elements is established as a function of element spacing. The reattachment length downstream of the element varies from 4 to 1.5 element heights, decreasing both with an increase in Reynolds number and a decrease in channel height.

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.

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.

Application of PIV Measurements and Snapshot POD Analysis in a Cylinder Head of Diesel Engine

2017 ◽  
Author(s):  
Zhenyang Zhang ◽  
Hongwei Ma ◽  
Chao Jin ◽  
Cheng Xue ◽  
Yunlong Huang
Keyword(s):  
Diesel Engine ◽  
Flow Field ◽  
Total Energy ◽  
Cylinder Head ◽  
Flow Fields ◽  
Coolant Flow ◽  
Flow Structures ◽  
Fuel Injector ◽  
Piv Measurements ◽  
Water Jacket

The characteristic of coolant flow field in the water jacket of a cylinder head plays an important role in heat exchange, which could even influence the diesel engine’s performance and service life. Measurements and analysis methods to coolant flow field are limited by the complex internal geometrical structure of the cylinder head. In this paper, flow fields in a small and complicated spatial structure are measured by particle image velocimetry (PIV) system and the data are analyzed using proper orthogonal decomposition (POD) method. Time varying coolant flow structures located among two valve seats, a fuel injector seat and a side wall in a real cylinder head are measured by a two dimensional PIV system. PIV results of three measuring planes are displayed in different ways to show flow structures in the water jacket. Distinctive areas can be recognized easily in distributions of different flow parameters. A snapshot POD method is employed to analyze PIV data. Flow structures, which contain different amount of energy, are decomposed into different modes by POD method. POD Mode 1 and ensemble mean flow field are compared together and the relevance index shows a relatively high similarity between these two flow fields. The results also indicate a significant convergence of energy distribution. Energy contained in Mode 1 varies from 22% to 61% of the total energy in different measuring planes. 90% of the total energy is captured in top 10% of the total modes which belong to low-order modes. Energy in high-order modes, which occupy more than 60% of the total modes, contains less than 1% of the total energy. In summary, this paper presents the application of PIV measurements to coolant flow field in a real cylinder head and data processing using a snapshot POD method to analyze PIV results. A set of comprehensive properties showing the spatial and temporal characteristics of coolant flow structure is discussed and concluded detailedly. The data obtained can be used to build an experimental database to optimize coolant flow field structures and verify CFD numerical simulations in order to promote coolant flow passage design and simulation credibility of the diesel engine cooling system.

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