Flow Field Investigation in a Low-Solidity Inducer by Laser-Doppler Velocimetry

1990 ◽  
Vol 112 (1) ◽  
pp. 91-97 ◽  
Author(s):  
A. Boccazzi ◽  
A. Perdichizzi ◽  
U. Tabacco
Keyword(s):  
Flow Field ◽  
Flow Rate ◽  
Reverse Flow ◽  
Field Investigation ◽  
Design Flow ◽  
Laser Doppler ◽  
Laser Doppler Velocimeter ◽  
Pressure Probe ◽  
Specific Work ◽  
Flow Angle

The results of an experimental investigation of the flow field within a low-solidity inducer at design and off-design flow rates are presented and discussed; particular attention is devoted to the analysis of the flow field, at the tip in front of the leading edge, for the flow rate close to the back-flow onset. The flow field was measured by means of a laser-Doppler velocimeter at four different axial positions upstream, within, and downstream of the inducer. Axial, tangential, and relative flow angle distributions, in the measuring planes, are presented for three different flow coefficients. At the lower flow rate, the plots show the presence of reverse flow in the region close to the hub downstream of the trailing edge. For the same flow rate, quite low axial velocities are detected at the tip. This is in agreement with pressure probe traverses carried out in a slightly downstream section; these measurements also show radial inward velocities of the same order of magnitude as the axial velocities. Circumferentially averaged losses were evaluated from specific work and total head rise given by pressure probes.

scholarly journals Flow Field Investigation in a Low Solidity Inducer by Laser Doppler Velocimeter

1989 ◽  
Author(s):  
A. Boccazzi ◽  
A. Perdichizzi ◽  
U. Tabacco
Keyword(s):  
Flow Field ◽  
Flow Rate ◽  
Reverse Flow ◽  
Field Investigation ◽  
Design Flow ◽  
Laser Doppler ◽  
Laser Doppler Velocimeter ◽  
Pressure Probe ◽  
Specific Work ◽  
Flow Angle

The results of an experimental investigation of the flow-field within a low solidity inducer at design and off design flow rate are presented and discussed; particular attention is devoted to the analysis of the flow-field, at the tip in front of the leading edge, for the flow rate close to the back-flow onset. The flow-field was measured by means of a laser doppler velocimeter at four different axial positions: upstream, within and downstream of the inducer. Axial, tangential and relative flow angle distributions, in the measuring planes, are presented for three different flow coefficients. At the lower flow rate, the plots show the presence of reverse flow in the region close to the hub downstream of the trailing edge. For the same flow rate, quite low axial velocities are detected at the tip. This is in agreement with pressure probe traverses carried out in a slightly downstream section; these measurements also show radial inward velocities of the same order of magnitude as the axial velocities. Circumferentially averaged losses were evaluated from specific work and total head rise given by pressure probes.

scholarly journals Laser-Doppler Velocimetry Measurements Inside a Backward Curved Centrifugal Fan

2001 ◽  
Vol 7 (3) ◽  
pp. 173-181
Author(s):  
Tong-Miin Liou ◽  
Meng-Yu Chen
Keyword(s):  
Flow Rate ◽  
Turbulence Intensity ◽  
Laser Doppler Velocimetry ◽  
Reverse Flow ◽  
Flow Region ◽  
Design Flow ◽  
Laser Doppler ◽  
Centrifugal Fan ◽  
Doppler Velocimetry ◽  
Flow Rates

Laser-Doppler velocimetry (LDV) measurements are presented of relative mean velocity and turbulence intensity components inside the impeller passage of a centrifugal fan with twelve backward curved blades at design, under-design, and over-design flow rates. Additional LDV measurements were also performed at the volute outlet to examine the uniformity of the outlet flow for the three selected flow rates. Complementary flow visualization results in the tongue region are further presented. It is found that the number of characteristic flow regions and the average turbulence level increase with decreasing air flow rate. For the case of under-design flow rate, there are a through-flow region on the suction side, a reverse flow region on the pressure side, and a shear layer region in between. The corresponding average turbulence intensity is as high as 9.1% of blade tip velocity.

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.

Investigation of the Surge Behavior of a Multi-Stage Axial Compressor With a Multi-Sensor Probe

2011 ◽  
Author(s):  
P. Waniczek ◽  
P. Jeschke ◽  
H. Schoenenborn ◽  
T. Metzler
Keyword(s):  
Flow Field ◽  
Velocity Vector ◽  
Reverse Flow ◽  
Axial Compressor ◽  
Leading Edge ◽  
Field Structure ◽  
Pressure Probe ◽  
High Time Resolution ◽  
Trailing Edge ◽  
Flow Angle

The surge behavior of the first rotor of an eight-stage aero engine high pressure compressor has been investigated experimentally. For that purpose, a new multi-hole pressure probe was developed and adapted to the axial compressor test rig. Due to the high time resolution measurements (more than 45000 measuring points per surge cycle) it is possible to investigate the dynamic flow field of a surge cycle in a time-accurate manner. The results especially show the complex flow field structure at the surge inception. At the rotor leading edge the flow shows perturbations with high amplitudes and initiates the surge event, whereas the flow at the rotor trailing edge is less influenced. The inflow vector turns around the leading edge of the blade relatively slowly. During that turn around three different characteristic flow conditions have been identified. These are ‘zero rotor turning’, ‘turbine-like flow’ and ‘no flow’. ‘No flow’ means, that the absolute velocity vector reaches a flow angle where it consists of a pure tangential velocity component. That is the point where the reverse flow phase is initiated. A 180° shift of the flow direction at the rotor trailing edge is the consequence. After a quasi-steady reverse flow the acceleration of the flow starts. In total, this paper gives new and fundamental insights into the unsteady flow field phenomena during various surge cycles. Especially the transient velocity vector imparts a good idea of the flow field structure of a surging compressor.

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.

Integrated Microcomputer-LDV Instrumentation for Studying Finite Wing Aerodynamics

1993 ◽  
Author(s):  
Abdollah Khodadoust
Keyword(s):  
Reynolds Number ◽  
Flow Field ◽  
Data Acquisition ◽  
Fiber Optic ◽  
Three Dimensional ◽  
Laser Doppler ◽  
Laser Doppler Velocimeter ◽  
Ice Accretion ◽  
Wing Model ◽  
Finite Wing

Abstract The effect of a simulated glaze ice accretion on the flow field of a three-dimensional wing is studied experimentally. A PC-based data acquisition and reduction system was used with a four-beam two-color fiber-optic laser Doppler velocimeter (LDV) to map the flow field along three spanwise cuts on the model. Results of the LDV measurements on the upper surface of the finite wing model without the simulated glaze ice accretion are presented for α = 0 degrees at Reynolds number of 1.5 million. Measurements on the centerline of the clean model compared favorably with theory.

scholarly journals Two Dimensional Flow Analysis of a Laboratory Centrifugal Pump

1990 ◽  
Author(s):  
S. M. Miner ◽  
R. D. Flack ◽  
P. E. Allaire
Keyword(s):  
Velocity Field ◽  
Stagnation Point ◽  
Centrifugal Pump ◽  
Flow Rate ◽  
Flow Analysis ◽  
Tangential Component ◽  
Design Flow ◽  
Experimental Results ◽  
Two Dimensional ◽  
Flow Angle

Two dimensional potential flow was used to determine the velocity field within a laboratory centrifugal pump. In particular, the finite element technique was used to model the impeller and volute simultaneously. The rotation of the impeller within the volute was simulated by using steady state solutions with the impeller in 10 different angular orientations. This allowed the interaction between the impeller and the volute to develop naturally as a result of the solution. The results for the complete pump model showed that there are circumferential asymmetries in the velocity field, even at the design flow rate. Differences in the relative velocity components were as large as 0.12 m/sec for the radial component and 0.38 m/sec for the tangential component, at the impeller exit. The magnitude of these variations was roughly 25% of the magnitude of the average radial and tangential velocities at the impeller exit. These asymmetries were even more pronounced at off design flow rates. The velocity field was also used to determine the location of the tongue stagnation point and to calculate the slip within the impeller. The stagnation point moved from the discharge side of the tongue to the impeller side of the tongue, as the flow rate increased from below design flow to above design flow. At design flow, values of slip ranged from 0.96 to 0.71, from impeller inlet to impeller exit. For all three types of data (velocity profiles, stagnation point location, and slip factor) comparison was made to laser velocimeter data, taken for the same pump. At the design flow, the computational and experimental results agreed to within 17% for the velocity magnitude, and 2° for the flow angle. The stagnation point locations coincided for the computational and experimental results, and the values for slip agreed to within 10%.

Three Dimensional Clocking Effects in a One and a Half Stage Transonic Turbine

2009 ◽  
Vol 132 (1) ◽  
Author(s):  
O. Schennach ◽  
J. Woisetschläger ◽  
B. Paradiso ◽  
G. Persico ◽  
P. Gaetani
Keyword(s):  
Flow Field ◽  
Three Dimensional ◽  
Fast Response ◽  
Secondary Flows ◽  
Pressure Probe ◽  
Time Resolved ◽  
Flow Angle ◽  
Aerodynamic Pressure ◽  
Velocity Flow ◽  
Transonic Turbine

This paper presents an experimental investigation of the flow field in a high-pressure transonic turbine with a downstream vane row (1.5 stage machine) concerning the airfoil indexing. The objective is a detailed analysis of the three-dimensional aerodynamics of the second vane for different clocking positions. To give an overview of the time-averaged flow field, five-hole probe measurements were performed upstream and downstream of the second stator. Furthermore in these planes additional unsteady measurements were carried out with laser Doppler velocimetry in order to record rotor phase-resolved velocity, flow angle, and turbulence distributions at two different clocking positions. In the planes upstream of the second vane, the time-resolved pressure field has been measured by means of a fast response aerodynamic pressure probe. This paper shows that the secondary flows of the second vane are significantly modified by the different clocking positions, in connection with the first vane modulation of the rotor secondary flows. An analysis of the performance of the second vane is also carried out, and a 0.6% variation in the second vane loss coefficient has been recorded among the different clocking positions.

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