Wake, Shock and Potential Field Interactions in a 1.5 Stage Turbine: Part II — Vane-Vane Interaction and Discussion of Results

2002 ◽  
Author(s):  
R. J. Miller ◽  
R. W. Moss ◽  
R. W. Ainsworth ◽  
N. W. Harvey
Keyword(s):  
High Pressure ◽  
Potential Field ◽  
Pressure Fluctuations ◽  
Interaction Mechanism ◽  
Fast Response ◽  
Rotor Blades ◽  
Suction Surface ◽  
Time Resolved ◽  
Pressure Transducers ◽  
The Individual

The composition of the time-resolved surface pressure field around a high-pressure rotor blade caused by the presence of neighbouring blade rows is investigated with the individual effects of wake, shock and potential field interaction being determined. Two test geometries are considered: first, a high-pressure turbine stage coupled with a swan-necked diffuser exit duct; secondly, the same high-pressure stage but with a vane located in the downstream duct. Both tests were conducted at engine-representative Mach and Reynolds numbers and experimental data was acquired using fast-response pressure transducers mounted on the mid-height streamline of the HP rotor blades. The results are compared to time-resolved computational predictions of the flowfield in order to aid interpretation of experimental results and to determine the accuracy with which the computation predicts blade interaction. In the first half of this paper it is shown that, in addition to the two main interaction mechanisms (upstream vane-rotor and rotor-downstream vane interactions, presented in Miller et al. [1]) a third interaction occurs. This new interaction mechanism is shown to be caused by the interaction between the downstream vane’s potential field and the upstream vane’s trailing edge potential field and shock. The unsteady rotor surface static pressure fluctuations caused by this interaction are shown to occur on the late rotor suction surface at a frequency corresponding to the difference in the numbers of upstream and downstream vanes. The second part to the paper discusses the mechanisms that cause vane-rotor-vane interaction. The rotor’s operating point is periodically altered as it passes the downstream vane. It is shown that for a large downstream vane, the flow conditions in the rotor passage, at any instant in time, are close to being steady state.

Wake, Shock, and Potential Field Interactions in a 1.5 Stage Turbine—Part II: Vane-Vane Interaction and Discussion of Results

2003 ◽  
Vol 125 (1) ◽  
pp. 40-47 ◽  
Author(s):  
R. J. Miller ◽  
R. W. Moss ◽  
R. W. Ainsworth ◽  
N. W. Harvey
Keyword(s):  
High Pressure ◽  
Potential Field ◽  
Pressure Fluctuations ◽  
Interaction Mechanism ◽  
Fast Response ◽  
Rotor Blades ◽  
Suction Surface ◽  
Time Resolved ◽  
Pressure Transducers ◽  
The Individual

The composition of the time-resolved surface pressure field around a high-pressure rotor blade caused by the presence of neighboring blade rows is investigated with the individual effects of wake, shock and potential field interaction being determined. Two test geometries are considered: first, a high-pressure turbine stage coupled with a swan-necked diffuser exit duct; secondly, the same high pressure stage but with a vane located in the downstream duct. Both tests were conducted at engine-representative Mach and Reynolds numbers and experimental data was acquired using fast-response pressure transducers mounted on the mid-height streamline of the HP rotor blades. The results are compared to time-resolved computational predictions of the flow field in order to aid interpretation of experimental results and to determine the accuracy with which the computation predicts blade interaction. In the first half of this paper it is shown that, in addition to the two main interaction mechanisms (upstream vane-rotor and rotor-downstream vane interactions, presented in Part I of this paper) a third interaction occurs. This new interaction mechanism is shown to be caused by the interaction between the downstream vane’s potential field and the upstream vane’s trailing edge potential field and shock. The unsteady rotor surface static pressure fluctuations caused by this interaction are shown to occur on the late rotor suction surface at a frequency corresponding to the difference in the numbers of upstream and downstream vanes. The second part to the paper discusses the mechanisms that cause vane-rotor-vane interaction. The rotor’s operating point is periodically altered as it passes the downstream vane. It is shown that for a large downstream vane, the flow conditions in the rotor passage, at any instant in time, are close to being steady state.

Wake, Shock, and Potential Field Interactions in a 1.5 Stage Turbine—Part I: Vane-Rotor and Rotor-Vane Interaction

2003 ◽  
Vol 125 (1) ◽  
pp. 33-39 ◽  
Author(s):  
R. J. Miller ◽  
R. W. Moss ◽  
R. W. Ainsworth ◽  
N. W. Harvey
Keyword(s):  
High Pressure ◽  
Potential Field ◽  
Pressure Field ◽  
Fast Response ◽  
Operating Conditions ◽  
Rotor Blades ◽  
Time Resolved ◽  
Pressure Transducers ◽  
Unsteady Pressure ◽  
The Individual

The composition of the time-resolved surface pressure field around a high-pressure rotor blade caused by the presence of neighboring blade rows is investigated, with the individual effects of wake, shock and potential field interaction being determined. Two test geometries are considered: first, a high-pressure turbine stage coupled with a swan-necked diffuser exit duct; secondly, the same high-pressure stage but with a vane located in the downstream duct. Both tests were conducted at engine-representative Mach and Reynolds numbers, and experimental data was acquired using fast-response pressure transducers mounted on the mid-height streamline of the HP rotor blades. The results are compared to time-resolved computational predictions of the flowfield in order to aid interpretation of experimental results and to determine the accuracy with which the computation predicts blade interaction. The paper is split into two parts: the first investigating the effect of the upstream vane on the unsteady pressure field around the rotor (vane-rotor interaction), and the second investigating the effect of the downstream vane on the unsteady pressure field around the rotor (rotor-vane interaction). The paper shows that at typical design operating conditions shock interaction from the upstream blade row is an order of magnitude greater than wake interaction and that with the design vane-rotor inter-blade gap the presence of the rotor causes a periodic increase in the strength of the vane trailing edge shock. The presence of the potential field of the downstream vane is found to affect significantly the rotor pressure field downstream of the Mach one surface within each rotor passage.

Wake, Shock and Potential Field Interactions in a 1.5 Stage Turbine: Part I — Vane-Rotor and Rotor-Vane Interaction

2002 ◽  
Author(s):  
R. J. Miller ◽  
R. W. Moss ◽  
R. W. Ainsworth ◽  
N. W. Harvey
Keyword(s):  
High Pressure ◽  
Potential Field ◽  
Pressure Field ◽  
Fast Response ◽  
Operating Conditions ◽  
Rotor Blades ◽  
Time Resolved ◽  
Pressure Transducers ◽  
Unsteady Pressure ◽  
The Individual

The composition of the time-resolved surface pressure field around a high-pressure rotor blade caused by the presence of neighboring blade rows is investigated, with the individual effects of wake, shock and potential field interaction being determined. Two test geometries are considered: first, a high-pressure turbine stage coupled with a swan-necked diffuser exit duct; secondly, the same high-pressure stage but with a vane located in the downstream duct. Both tests were conducted at engine-representative Mach and Reynolds numbers, and experimental data was acquired using fast-response pressure transducers mounted on the mid-height streamline of the HP rotor blades. The results are compared to time-resolved computational predictions of the flowfield in order to aid interpretation of experimental results and to determine the accuracy with which the computation predicts blade interaction. The paper is split into two parts, the first investigating the effect of the upstream vane on the unsteady pressure field around the rotor (vane-rotor interaction) and the second investigating the effect of the downstream vane on the unsteady pressure field around the rotor (rotor-vane interaction). The paper shows that at typical design operating conditions shock interaction from the upstream blade row is an order of magnitude greater than wake interaction and that with the design vane-rotor inter-blade gap the presence of the rotor causes a periodic increase in the strength of the vane trailing edge shock. The presence of the potential field of the downstream vane is found to affect significantly the rotor pressure field downstream of the Mach one surface within each rotor passage.

Unsteady Vortices and Blade Loading in a High-Pressure Turbine

2009 ◽  
Author(s):  
Dongil Chang ◽  
Stavros Tavoularis
Keyword(s):  
High Pressure ◽  
Stokes Equations ◽  
Pressure Fluctuations ◽  
Rotor Blades ◽  
Navier Stokes ◽  
Navier Stokes Equations ◽  
Time Resolved ◽  
Blade Loading ◽  
Pressure Losses ◽  
Horseshoe Vortices

Unsteady flow in a transonic, single-stage, high-pressure, axial turbine has been investigated numerically by solving the URANS (Unsteady Reynolds-Averaged Navier-Stokes) equations with the SST (Shear Stress Transport) turbulence model. Interest has focused on the identification and effects of the quasi-stationary vane and blade horseshoe vortices, vane and blade passage vortices, vane and blade trailing edge vortices, and blade tip leakage vortices. Moreover, two types of unsteady vortices, not discussed explicitly in the previous literature, have been identified and termed “axial gap vortices” and “crown vortices”. All vortices have been clearly and distinctly identified using a modified form of the Q criterion, which is less sensitive to the set threshold than the original version. The use of pathlines and iso-contours of static pressure, axial vorticity and entropy has been further exploited to distinguish the different types of vortices from each other and to mark their senses of rotation and strengths. The influence of these vortices on the entropy distribution at the outlet has been investigated. The observed high total pressure losses in the turbine at blade midspan have been connected to the action of passage vortices. The formation and disappearance processes of unsteady vortices located in the spacing between the stator and the rotor have been time-resolved. These vortices are roughly aligned with the leading edges of the rotor blades and their existence depends on the position of the blade with respect to the upstream vanes. In addition, the present study focuses on the unsteady blade loading that influences vibratory stresses. Contours of the time-dependent surface pressure on the rotor blade have demonstrated the presence of large pressure fluctuations near the front of the blade suction sides; these pressure fluctuations have been associated with the periodic passages of shock waves originating at the vane trailing edges.

Effect of Clocking on the Second Stator Pressure Field of a One and a Half Stage Transonic Turbine

2004 ◽  
Author(s):  
J. Gadea ◽  
R. De´nos ◽  
G. Paniagua ◽  
N. Billiard ◽  
C. H. Sieverding
Keyword(s):  
Pressure Distribution ◽  
Static Pressure ◽  
Pressure Field ◽  
Pressure Fluctuations ◽  
Leading Edge ◽  
Fast Response ◽  
Time Resolved ◽  
Pressure Transducers ◽  
Static Pressure Distribution ◽  
Transonic Turbine

This paper focuses on the experimental investigation of the time-averaged and time-resolved pressure field of a second stator tested in a one and a half stage high-pressure transonic turbine. The effect of clocking and its influence on the aerodynamic and mechanical behaviour are investigated. The test program includes four different clocking positions, i.e. relative pitch-wise positions between the first and the second stator. Pneumatic probes located upstream and downstream of the second stator provide the time-averaged component of the pressure field. For the second stator airfoil, both time-averaged and time-resolved surface static pressure fields are measured at 15, 50 and 85% span with fast response pressure transducers. Regarding the time-averaged results, the effect of clocking is mostly observed in the leading edge region of the second stator, the largest effects being observed at 15% span. The surface static pressure distribution is changed locally, which is likely to affect the overall performance of the airfoil. The phase-locked averaging technique allows to process the time-resolved component of the data. The pressure fluctuations are attributed to the passage of pressure gradients linked to the traversing of the upstream rotor. The pattern of these fluctuations changes noticeably as a function of clocking. Finally, the time-resolved pressure distribution is integrated along the second stator surface to determine the unsteady forces applied on the vane. The magnitude of the unsteady force is very dependent on the clocking position.

The Effect of the Operating Point on the Pressure Fluctuations at the Blade Passage Frequency in the Volute of a Centrifugal Pump

2002 ◽  
Vol 124 (3) ◽  
pp. 784-790 ◽  
Author(s):  
Jorge L. Parrondo-Gayo ◽  
Jose´ Gonza´lez-Pe´rez ◽  
Joaquı´n Ferna´ndez-Francos
Keyword(s):  
Centrifugal Pump ◽  
Pressure Fluctuations ◽  
Fast Response ◽  
Strong Increase ◽  
Flow Rates ◽  
Blade Passage ◽  
Pressure Transducers ◽  
Leading Role ◽  
Dynamic Forces ◽  
Response Pressure

An experimental investigation is presented which analyzes the unsteady pressure distribution existing in the volute of a conventional centrifugal pump with a nondimensional specific speed of 0.48, for flow-rates from 0% to 160% of the best-efficiency point. For that purpose, pressure signals were obtained at 36 different locations along the volute casing by means of fast-response pressure transducers. Particular attention was paid to the pressure fluctuations at the blade passage frequency, regarding both amplitude and phase delay relative to the motion of the blades. Also, the experimental data obtained was used to adjust the parameters of a simple acoustic model for the volute of the pump. The results clearly show the leading role played by the tongue in the impeller-volute interaction and the strong increase in the magnitude of dynamic forces and dipole-like sound generation in off-design conditions.

Prestall Instability in Axial Flow Compressors

2020 ◽  
Vol 142 (7) ◽  
Author(s):  
Mario Eck ◽  
Roland Rückert ◽  
Dieter Peitsch ◽  
Marc Lehmann
Keyword(s):  
Pressure Fluctuations ◽  
Axial Compressor ◽  
Axial Flow ◽  
Leading Edge ◽  
Propagation Speed ◽  
Flow Coefficient ◽  
Spectral Signature ◽  
Time Resolved ◽  
Pressure Transducers ◽  
Flow Disturbances

Abstract The aim of the present paper is to improve the physical understanding of discrete prestall flow disturbances developing in the tip area of the compressor rotor. For this purpose, a complementary instrumentation was used in a single-stage axial compressor. A set of pressure transducers evenly distributed along the circumference surface mounted in the casing near the rotor tip leading edges measures the time-resolved wall pressures simultaneously to an array of transducers recording the chordwise static pressures. The latter allows for plotting quasi-instantaneous casing pressure contours. Any occurring flow disturbances can be properly classified using validated frequency analysis methods applied to the data from the circumferential sensors. While leaving the flow coefficient constant, a continuously changing number of prestall flow disturbances appears to be causing a unique spectral signature, which is known from investigations on rotating instability. Any arising number of disturbances is matching a specific mode order found within this signature. While the flow coefficient is reduced, the propagation speed of prestall disturbances increases linearly, and meanwhile, the speed seems to be independent from the clearance size. Casing contour plots phase-locked to the rotor additionally provide a strong hint on prestall disturbances clearly not to be caused by a leading edge separation. Data taken beyond the stalling limit demonstrate a complex superposition of stall cells and flow disturbances, which the title “prestall disturbance” therefore does not fit to precisely any more. Different convection speeds allow the phenomena to be clearly distinguished from each other. Furthermore, statistical analysis of the pressure fluctuations caused by the prestall disturbances offer the potential to use them as a stall precursor or to quantify the deterioration of the clearance height between the rotor blade tips and the casing wall during the lifetime of an engine.

Upstream Potential Propagation Effects of Unsteady Stator-Rotor Interaction in an Axial Flow Blower: Numerical Analysis and Experimental Validation

2006 ◽  
Author(s):  
J. M. Ferna´ndez Oro ◽  
K. M. Argu¨elles Di´az ◽  
C. Santolaria Morros ◽  
R. Ballesteros Tajadura
Keyword(s):  
Pressure Fluctuations ◽  
Axial Flow ◽  
Leading Edge ◽  
Potential Effect ◽  
Potential Interaction ◽  
Rotor Blades ◽  
Axial Distance ◽  
Pressure Transducers ◽  
Wake Interactions ◽  
Rotor Stator Interaction

The potential effect of the inlet guide vanes blockage is predominant in an axial one-stage configuration when the upstream flow field is considered. In the same way, rotor downstream, the main unsteadiness is provoked by the rotor wakes mixing-out at the machine discharge. Nevertheless, if the gap between the rows is significantly reduced, the stator wakes are not allowed to be mixed out before impinging the rotor blades, so a chopping effect overcomes, stretching and tilting them, and generating wake-wake interactions and new loss sources at the exit. On a similar trend, it is expected that a reduced axial gap allows the potential unsteadiness of the rotor blockage between the blades to be propagated upstream, modulating the flow conditions at the stator passages, and even at vanes leading edge locations. In this paper, the evolution of the rotor potential interaction within the stator passages and up to the vanes leading edge is analyzed. The main goal is placed on the analysis of the propagation, relating the axial distance with the attenuation of those potential mechanisms. A numerical 3D simulation of a complete single stage axial flow blower has been developed and executed using a commercial code that resolves the URANS set of equations. The axial gap between the 13-IGVs stator and the 9-blade rotor has been modified in order to evaluate its influence on the potential distortion propagated upstream of the stator. For the closing of turbulence, a LES scheme with a Smagorinsky-Lilly model is used in the computations. Finally, due to the LES characteristics, a phase-averaged procedure has to be introduced for the simulation post-processing. Complementary, experimental measurements have been carried out over a test rig with modifiable axial gap between the fixed and rotating blade rows. As a matter of fact, pressure transducers were placed all along the machine shroud to capture pressure fluctuations related to potential sources radiated from the rotor blades. These measurements have been analyzed using frequential analysis, which is essential to identify the origin of the flow inlet distortions. The final objective is to complete the rotor-stator interaction scenario both downstream and upstream the stage. Previous works were focused on the downstream conditions and now the upstream potential propagation is studied in detail.

Past Developments and Current Advancements in Unsteady Pressure Measurements in Turbomachines

2018 ◽  
Vol 140 (11) ◽  
Author(s):  
Jan Lepicovsky ◽  
David Simurda
Keyword(s):  
Pressure Measurement ◽  
High Speed ◽  
Measurement Techniques ◽  
Fast Response ◽  
Future Research ◽  
Flow Measurements ◽  
Time Resolved ◽  
Turbine Engine ◽  
Pressure Transducers ◽  
Unsteady Pressure

The aim of this paper is to review, summarize, and record long-term experience with development and application of aerodynamic probes with built-in miniature pressure transducers for unsteady pressure measurement and industrial research in turbomachine components. The focus of the first half of the paper is on the work performed at VZLU Prague, Czech Republic (Secs. 3–8). The latest development in unsteady pressure measurement techniques and data reduction methodology suitable for future research in highly loaded, high-speed turbine engine components performed at NASA GRC Cleveland, OH, is reported in Secs. 8–15 of this paper. Excellent reviews of similar activities at ETH Zürich, Switzerland by Kupferschmied, et al. (2000, “Time-Resolved Flow Measurements With Fast-Response Aerodynamic Probes in Turbomachines,” Meas. Sci. Technol., 11(7), pp. 1036–1054) and at VKI Rhode-Sain-Genèse, Belgium by Sieverding, et al. (2000, “Measurement Techniques for Unsteady Flows in Turbomachines,” Exp. Fluids, 28(4), pp. 285–321) were already reported and are acknowledged here. A short list of reported accomplishments achieved by other researchers at various laboratories is also reported for completeness. The authors apologize to those whose contributions are not reported here. It is just an unfortunate oversight, not an intentional omission.

scholarly journals Evaluation of supplementary comparison EURAMAT.M.P-S14 in the range 50 MPa to 1 GPa of hydraulic gauge pressure

ACTA IMEKO ◽  
2018 ◽  
Vol 7 (1) ◽  
pp. 76
Author(s):  
Jens Könemann
Keyword(s):  
High Pressure ◽  
High Pressures ◽  
Individual Measurement ◽  
Transfer Standard ◽  
Pressure Transducers ◽  
Comparison Results ◽  
Gauge Pressure ◽  
The Individual ◽  
Rich Data ◽  
Almost All

In this work, we present a mathematical procedure to evaluate a hydraulic gauge pressure comparison in the range to 1 GPa piloted by PTB and using a transfer standard consisting of two series of modern high-pressure transducers, i.e. eight pressure transducers in total. This set of parallel arranged transducers should ensure reliability of the transfer standard at high pressures and provide rich data for testing the performance of modern high-pressure transducers. The analysis of the comparison results was based on the evaluation of the individual measurement deviations of these transducers with respect to the laboratory standards, whereas the corresponding comparison reference values and their uncertainty were determined separately at each pressure point and pressure transducer. All these results were summarized to derive the degree of equivalence for each laboratory at each pressure which was found for all laboratories to be consistent at almost all pressures.

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