Periodical Unsteady Flow Within a Rotor Blade Row of an Axial Compressor—Part I: Flow Field at Midspan

2008 ◽  
Vol 130 (4) ◽  
pp. 041004 ◽  
Author(s):  
Ronald Mailach ◽  
Ingolf Lehmann ◽  
Konrad Vogeler
Keyword(s):  
Flow Field ◽  
Unsteady Flow ◽  
Rotor Blade ◽  
Axial Compressor ◽  
Blade Row

Periodical Unsteady Flow Within a Rotor Blade Row of an Axial Compressor: Part II — Wake–Tip Clearance Vortex Interaction

2007 ◽  
Author(s):  
Ronald Mailach ◽  
Ingolf Lehmann ◽  
Konrad Vogeler
Keyword(s):  
Flow Field ◽  
Unsteady Flow ◽  
Rotor Blade ◽  
Pressure Sensors ◽  
Tip Clearance ◽  
Experimental Investigations ◽  
Lower Velocity ◽  
Blade Row ◽  
Blade Tip ◽  
Tip Clearance Vortex

In this two-part paper results of the periodical unsteady flow field within the third rotor blade row of the four-stage Dresden Low-Speed Research Compressor are presented. The main part of the experimental investigations was performed using Laser-Doppler-Anemometry. Results of the flow field at several spanwise positions between midspan and rotor blade tip will be discussed. In addition time-resolving pressure sensors at midspan of the rotor blades provide information about the unsteady profile pressure distribution. In part II of the paper the flow field in the rotor blade tip region will be discussed. The experimental results reveal a strong periodical interaction of the incoming stator wakes and the rotor blade tip clearance vortices. Consequently, in the rotor frame of reference the tip clearance vortices are periodical with the stator blade passing frequency. Due to the wakes the tip clearance vortices are separated into different segments. Along the mean vortex trajectory these parts can be characterised by alternating patches of higher and lower velocity and flow turning or subsequent counterrotating vortex pairs. These flow patterns move downstream along the tip clearance vortex path in time. As a result of the wake influence the orientation and extension of the tip clearance vortices as well as the flow blockage periodically vary in time.

scholarly journals Experimental Study of a 3D Wake Decay and Secondary Flows Behind a Rotor Blade Row of a Low Speed Compressor Stage

1996 ◽  
Author(s):  
A. S. Witkowski ◽  
T. J. Chmielniak ◽  
M. D. Strozik
Keyword(s):  
Flow Field ◽  
Unsteady Flow ◽  
Secondary Flow ◽  
Rotor Blade ◽  
Three Dimensional ◽  
Secondary Flows ◽  
Operating Conditions ◽  
Tip Clearance ◽  
Compressor Stage ◽  
Blade Row

Detailed measurements have been performed in a low pressure axial flow compressor stage to investigate the structure of the secondary flow field and the three-dimensional wake decay at different axial locations before and behind the rotor. The three dimensional flow field upstream and downstream of the rotor and on the centerline of the stator blade passage have been sampled periodically using a straight and a 90 degree triple-split fiber probe. Radial measurements at 39 radial stations were carried out at chosen axial positions in order to get the span-wise characteristics of the unsteady flow. Taking the experimental values of the unsteady flow velocities and turbulence properties, the effects of the rotor blade wake decay and secondary flow on the blade row spacing and stator passage flow at different operating conditions are discussed. For the normal operating point, the component of radial turbulent intensities in the leakage-flow mixing region is found to be much higher than the corresponding axial and tangential components. But for a higher value of the flow coefficient the relations are different.The results of the experiments show that triple-split fiber probes, straight and 90 degree measurements, combined with the ensemble average technique are a very useful method for the analysis of rotor flow in turbomachinery. Tip clearance vortex, secondary flow near the hub and radial flow in the wake, turbulent intensity and Reynolds stresses and also the decay of the rotor wakes can be obtained by this method.

Periodical Unsteady Flow Within a Rotor Blade Row of an Axial Compressor: Part I — Flow Field at Midspan

2007 ◽  
Author(s):  
Ronald Mailach ◽  
Ingolf Lehmann ◽  
Konrad Vogeler
Keyword(s):  
Flow Field ◽  
Unsteady Flow ◽  
Pressure Distribution ◽  
Rotor Blade ◽  
Laser Doppler Anemometry ◽  
Pressure Sensors ◽  
Stability Limit ◽  
Rotor Blades ◽  
Experimental Investigations ◽  
Blade Row

In this two-part paper results of the periodical unsteady flow field within the third rotor blade row of the four-stage Dresden Low-Speed Research Compressor are presented. The main part of the experimental investigations was performed using Laser-Doppler-Anemometry. Results of the flow field at several spanwise positions between midspan and rotor blade tip will be discussed. In addition time-resolving pressure sensors at midspan of the rotor blades provide information about the unsteady profile pressure distribution. In part I of the paper the flow field at midspan of the rotor blade row will be discussed. Different aspects of the blade row interaction process are considered for the design point and an operating point near the stability limit. The periodical unsteady blade-to-blade velocity field is dominated by the incoming stator wakes, while the potential effect of the stator blades is of minor influence. The inherent vortex structures and the negative jet effect, which is coupled to the wake appearance, are clearly resolved. Furthermore the time-resolved profile pressure distribution of the rotor blades is discussed. Although the negative jet effect within the rotor blade passage is very pronounced the rotor blade pressure distribution is nearly independent from the convectively propagating chopped stator wakes.

Periodical Unsteady Flow Within a Rotor Blade Row of an Axial Compressor—Part II: Wake-Tip Clearance Vortex Interaction

2008 ◽  
Vol 130 (4) ◽  
Author(s):  
Ronald Mailach ◽  
Ingolf Lehmann ◽  
Konrad Vogeler
Keyword(s):  
Flow Field ◽  
Unsteady Flow ◽  
Rotor Blade ◽  
Laser Doppler Anemometry ◽  
Pressure Sensors ◽  
Tip Clearance ◽  
Experimental Investigations ◽  
Blade Row ◽  
Blade Tip ◽  
Tip Clearance Vortex

In this two-part paper, results of the periodical unsteady flow field within the third rotor blade row of the four-stage Dresden low-speed research compressor are presented. The main part of the experimental investigations was performed using laser Doppler anemometry. Results of the flow field at several spanwise positions between midspan and rotor blade tip will be discussed. In addition, time-resolving pressure sensors at midspan of the rotor blades provide information about the unsteady profile pressure distribution. In Part II of the paper, the flow field in the rotor blade tip region will be discussed. The experimental results reveal a strong periodical interaction of the incoming stator wakes and the rotor blade tip clearance vortices. Consequently, in the rotor frame of reference, the tip clearance vortices are periodical with the stator blade passing frequency. Due to the wakes, the tip clearance vortices are separated into different segments. Along the mean vortex trajectory, these parts can be characterized by alternating patches of higher and lower velocities and flow turning or subsequent counter-rotating vortex pairs. These flow patterns move downstream along the tip clearance vortex path in time. As a result of the wake influence, the orientation and extension of the tip clearance vortices as well as the flow blockage periodically vary in time.

Steady and Unsteady Flow Field in a Multistage Low-Speed Axial Compressor: A Test Case

2008 ◽  
Author(s):  
Mario Ku¨nzelmann ◽  
Ralf Mu¨ller ◽  
Ronald Mailach ◽  
Konrad Vogeler
Keyword(s):  
Flow Field ◽  
Unsteady Flow ◽  
Laser Doppler Anemometry ◽  
Guide Vane ◽  
Axial Compressor ◽  
Inlet Guide Vane ◽  
Test Case ◽  
Data Set ◽  
Low Speed ◽  
Blade Row

This paper introduces a new test case for compressor aerodynamics. The dataset is provided for the Dresden four-stage Low-Speed Research Compressor (LSRC), which was put into operation in 1995. The compressor consists of four identical stages, which are preceded by an inlet guide vane. The data set will be provided for the reference blading of the compressor with cantilevered stator vanes. This blading was developed on the basis of the profiles of a middle stage of a high-pressure compressor of a jet engine. This paper makes available the blading geometry as well as a variety of flow field measurement results. This includes the compressor map, selected pressure distributions and other results of flow field measurements with conventional techniques (e.g. Pitot probes, 5-hole probes). Furthermore different aspects of blade row interactions were addressed in this compressor within recent years. The periodical unsteady flow field within a selected rotor blade row was investigated using Laser-Doppler-Anemometry. Further results on the unsteady profile pressures and profile boundary layers will be provided. Supplementary, numerical results will be compared to the experiments. Results are available for several stages of the compressor and different operating points. With this test case a unique database for the aerodynamics in a multistage axial compressor will be provided that can be used for the validation of numerical codes.

Evaluation of a Flow Measurement Probe Influence on the Flow Field in High Speed Axial Compressors

2021 ◽  
Author(s):  
Ryosuke Seki ◽  
Satoshi Yamashita ◽  
Ryosuke Mito
Keyword(s):  
Flow Field ◽  
Approximation Method ◽  
High Speed ◽  
Static Pressure ◽  
Axial Compressor ◽  
Pressure Change ◽  
Operating Point ◽  
Blade Row ◽  
Probe Insertion ◽  
Probe Geometry

Abstract The aerodynamic effects of a probe for stage performance evaluation in a high-speed axial compressor are investigated. Regarding the probe measurement accuracy and its aerodynamic effects, the upstream/downstream effects on the probe and probe insertion effects are studied by using an unsteady computational fluid dynamics (CFD) analysis and by verifying in two types of multistage high-speed axial compressor measurements. The probe traverse measurements were conducted at the stator inlet and outlet in each case to evaluate blade row performance quantitatively and its flow field. In the past study, the simple approximation method was carried out which considered only the interference of the probe effect based on the reduction of the mass flow by the probe blockage for the compressor performance, but it did not agree well with the measured results. In order to correctly and quantitatively grasp the mechanism of the flow field when the probe is inserted, the unsteady calculation including the probe geometry was carried out in the present study. Unsteady calculation was performed with a probe inserted completely between the rotor and stator of a 4-stage axial compressor. Since the probe blockage and potential flow field, which mean the pressure change region induced by the probe, change the operating point of the upstream rotor and increase the work of the rotor. Compared the measurement result with probe to a kiel probe setting in the stator leading edge, the total pressure was increased about 2,000Pa at the probe tip. In addition, the developed wake by the probe interferes with the downstream stator row and locally changes the static pressure at the stator exit. To evaluate the probe insertion effect, unsteady calculations with probe at three different immersion heights at the stator downstream in an 8-stage axial compressor are performed. The static pressure value of the probe tip was increased about 3,000Pa in the hub region compared to tip region, this increase corresponds to the measurement trend. On the other hand, the measured wall static pressure showed that there is no drastic change in the radial direction. In addition, when the probe is inserted from the tip to hub region in the measurement, the blockage induced by the probe was increased. As a result, operating point of the stator was locally changed, and the rise of static pressure of the stator increased when the stator incidence changed. These typical results show that unsteady simulations including probe geometry can accurately evaluate the aerodynamic effects of probes in the high-speed axial compressor. Therefore, since the probe will pinpointed and strong affects the practically local flow field in all rotor upstream passage and stator downstream, as for the probe measurement, it is important to pay attention to design the probe diameter, the distance from the blade row, and its relative position to the downstream stator. From the above investigations, a newly simple approximation method which includes the effect of the pressure change evaluation by the probe is proposed, and it is verified in the 4-stage compressor case as an example. In this method, the effects of the distance between the rotor trailing edge (T.E.) and the probe are considered by the theory of the incompressible two-dimensional potential flow. The probe blockage decreases the mass flow rate and changes the operating point of the compressor. The verification results conducted in real compressor indicate that the correct blockage approximation enables designer to estimate aerodynamic effects of the probe correctly.

Flow Structure and Unsteady Behavior of Hub-Corner Separation in a Stator Cascade of a Multi-Stage Transonic Axial Compressor

2018 ◽  
Author(s):  
Seishiro Saito ◽  
Kazutoyo Yamada ◽  
Masato Furukawa ◽  
Keisuke Watanabe ◽  
Akinori Matsuoka ◽  
...  
Keyword(s):  
Data Mining ◽  
Flow Field ◽  
Unsteady Flow ◽  
Axial Compressor ◽  
Flow Fields ◽  
Suction Surface ◽  
Corner Separation ◽  
High Loss ◽  
Stator Blade ◽  
Transonic Axial Compressor

This paper describes unsteady flow phenomena of a two-stage transonic axial compressor, especially the flow field in the first stator. The stator blade with highly loaded is likely to cause a flow separation on the hub, so-called hub-corner separation. The flow mechanism of the hub-corner separation in the first stator is investigated in detail using a large-scale detached eddy simulation (DES) conducted for its full-annulus and full-stage with approximately 4.5 hundred million computational cells. The detailed analysis of complicated flow fields in the compressor is supported by data mining techniques. The data mining techniques applied in the present study include vortex identification based on the critical point theory and topological analysis of the limiting streamline pattern. The simulation results show that the flow field in the hub-corner separation is dominated by a tornado-type separation vortex. In the time averaged flow field, the hub-corner separation vortex rolls up from the hub wall, which is generated by the interaction between the mainstream flow, the leakage flow from the front partial clearance and the secondary flow across the blade passage toward the stator blade suction side. The hub-corner separation vortex suffers a vortex breakdown near the mid chord, where the high loss region due to the hub-corner separation expands drastically. In the rear part of the stator passage, a high loss region is migrated radially outward by the induced velocity of the hub-corner separation vortex. The flow field in the stator is influenced by the upstream and downstream rotors, which makes it difficult to understand the unsteady effects. The unsteady flow fields are analyzed by applying the phase-locked ensemble averaging technique. It is found from the phase-locked flow fields that the wake interaction from the upstream rotor has more influence on the stator flow field than the shock wave interaction from the downstream rotor. In the unsteady flow field, a focal-type separation also emerges on the blade suction surface, but it is periodically swept away by the wake passing of the upstream rotor. The separation vortex on the hub wall connects with the one on the blade suction surface, forming an arch-like vortex.

A Comparison Between the Design Point and Near-Stall Performance of an Axial Compressor

1990 ◽  
Vol 112 (1) ◽  
pp. 109-115 ◽  
Author(s):  
N. M. McDougall
Keyword(s):  
Rotor Blade ◽  
Three Dimensional ◽  
Axial Compressor ◽  
Pressure Rise ◽  
Tip Clearance ◽  
Tip Clearance Flow ◽  
Design Point ◽  
Blade Row ◽  
Clearance Flow ◽  
Stator Blade

Detailed measurements have been made within an axial compressor operating both at design point and near stall. Rotor tip clearance was found to control the performance of the machine by influencing the flow within the rotor blade passages. This was not found to be the case in the stator blade row, where hub clearance was introduced beneath the blade tips. Although the passage flow was observed to be altered dramatically, no significant changes were apparent in the overall pressure rise or stall point. Small tip clearances in the rotor blade row resulted in the formation of corner separations at the hub, where the blade loading was highest. More representative clearances resulted in blockage at the tip due to the increased tip clearance flow. The effects that have been observed emphasize both the three-dimensional nature of the flow within compressor blade passages, and the importance of the flow in the endwall regions in determining the overall compressor performance.

Large-Scale DES Analysis of Unsteady Flow Field in a Transonic Axial Compressor

2016 ◽  
Vol 2016 (0) ◽  
pp. J0520201
Author(s):  
Yuki TAMURA ◽  
Seishiro SAITO ◽  
Masato FURUKAWA ◽  
Kazutoyo YAMADA ◽  
Akinori MATUOKA ◽  
...  
Keyword(s):  
Flow Field ◽  
Unsteady Flow ◽  
Large Scale ◽  
Axial Compressor ◽  
Transonic Axial Compressor

Effects of Tip Clearance on Unsteady Flow Characteristics in an Axial Turbine Stage

2009 ◽  
Author(s):  
Hao Sun ◽  
Jun Li ◽  
Zhenping Feng
Keyword(s):  
Flow Field ◽  
Unsteady Flow ◽  
Rotor Blade ◽  
Suction Side ◽  
Tip Clearance ◽  
Leakage Flow ◽  
Turbine Stage ◽  
Tip Leakage Flow ◽  
Tip Leakage ◽  
Blade Tip

The clearance between the rotor blade tip and casing wall in turbomachinery passages induces leakage flow loss and thus degrades aerodynamic performance of the machine. The flow field in turbomachinery is significantly influenced by the rotor blade tip clearance size. To investigate the effects of tip clearance size on the rotor-stator interaction, the turbine stage profile from Matsunuma’s experimental tests was adopted, and the unsteady flow fields with two tip clearance sizes of 0.67% and 2.00% of blade span was numerical simulated based on Harmonic method using NUMECA software. By comparing with the domain scaling method, the accuracy of the harmonic method was verified. The interaction mechanism between the stator wake and the leakage flow was investigated. It is found that the recirculation induced by the stator wake is separated by a significant “interaction line” from the flow field close to the suction side in the clearance region. The trend of the pressure fluctuation is contrary on both sides of the line. When the stator wakes pass by the suction side, the pressure field fluctuates and the intensity of the tip leakage flow varies. With the clearance size increasing, the “interaction line” is more far away from the suction side and the intensity of tip leakage flow also fluctuates more strongly.

Sign in / Sign up

Export Citation Format

Share Document