Time Resolved Measurements in an Annular Compressor Cascade With High Aerodynamic Loading

2002 ◽  
Author(s):  
Jo¨rg Weidenfeller ◽  
Martin Lawerenz
Keyword(s):  
Pressure Sensors ◽  
Experimental Investigations ◽  
Hot Wire ◽  
Compressor Cascade ◽  
Time Resolved ◽  
Blade Loading ◽  
Inlet Velocity ◽  
Aerodynamic Loading ◽  
Flow Phenomena ◽  
Time Resolved Measurements

In order to identify unsteady flow phenomena this paper presents experimental investigations inside an isolated compressor cascade under off-design conditions. The results of extensive time resolved measurements, which were performed by piezo-resistive pressure sensors and hot wire anemometry show an interaction of aerodynamic and acoustic mechanisms. For a certain operating range the measurements indicate, that vortices, caused by boundary layer separations, oscillate with the pipe mode of the test section. In addition so-called rotating instabilities occur at high blade loading. They rotate with 48% of the circumferential component of the inlet velocity.

Three Dimensional Flow Field in a Highly Loaded Compressor Cascade

2014 ◽  
Author(s):  
Christian Beselt ◽  
Mario Eck ◽  
Dieter Peitsch
Keyword(s):  
Static Pressure ◽  
Vortex Breakdown ◽  
Three Dimensional ◽  
Flow Structures ◽  
Hot Wire ◽  
Compressor Cascade ◽  
Three Dimensional Flow ◽  
Time Resolved ◽  
Blade Loading ◽  
Passage Vortex

Within the present paper a detailed experimental investigation is presented. The influence of blade loading on the development and interaction of secondary flow structures within an annular compressor stator cascade is examined. Experimental results at 3% chord hub clearance were obtained at four different blade loadings. Included are blade and endwall flow visualization, time resolved measurements of the static pressure on the endwall and radial-circumferential hot-wire traverse measurements within the passage as well as five-hole probe traverse measurements at the inlet and the outlet of the passage. The experimentally obtained results give detailed insight on the effect of the incidence on the development and interaction of the clearance vortex, horse-shoe vortex and the passage vortex. Furthermore it will be shown that a vortex breakdown of the clearance vortex occurs at higher loadings.

Influence of Mach Number and Aerodynamic Loading on Rotating Instability in an Annular Compressor Cascade

2012 ◽  
Author(s):  
Christian Beselt ◽  
Dieter Peitsch
Keyword(s):  
Mach Number ◽  
Flow Field ◽  
Steady Flow ◽  
Field Measurements ◽  
Sudden Increase ◽  
Compressor Cascade ◽  
Time Resolved ◽  
Aerodynamic Loading ◽  
Rotating Instability ◽  
Time Resolved Measurements

An experimental study was conducted to investigate the influence of Mach number and aerodynamic loading on Rotating Instability (RI). Investigations were performed on an annular compressor cascade with radial clearance at the hub. In addition to steady flow field measurements, time resolved measurements of static wall-pressure at the hub, close to the tip clearance, were performed. For a specific range of incidence angles, RI could be detected at all flow speeds (Ma = 0.2–0.7). Shortly before the inception of RI, a sudden increase in pressure loss coefficient and outflow angle was detected by steady flow field measurements. The time resolved measurements showed an abruptly broadband increase of amplitude in the frequency range, in which RI occurs at higher loadings. RI propagates with 25–33% of the circumferential component of the upstream flow speed. Furthermore it is possible to scale the power spectral density function of the unsteady data with Strouhal number.

scholarly journals Experimental and numerical results of active flow control on a highly loaded stator cascade

2011 ◽  
Vol 225 (7) ◽  
pp. 907-918 ◽  
Author(s):  
M Hecklau ◽  
C Gmelin ◽  
W Nitsche ◽  
F Thiele ◽  
A Huppertz ◽  
...  
Keyword(s):  
Flow Control ◽  
Active Flow Control ◽  
Numerical Results ◽  
Pressure Probe ◽  
Compressor Cascade ◽  
Time Resolved ◽  
Inlet Velocity ◽  
Wide Range ◽  
Active Flow ◽  
Highly Loaded

This article presents experimental and numerical results for a compressor cascade with active flow control. Steady and pulsed blowing has been used to control the secondary flow and separation characteristics of a highly loaded controlled diffusion airfoil. Investigations were performed at the design incidence for blowing ratios from approximately 0.7 to 3.0 (jet-to-inlet velocity) and a Reynolds number of 840 000 (based on axial chord and inlet velocity). Detailed flow field data were collected using a five-hole pressure probe, pressure taps on the blade surfaces, and time-resolved Particle Image Velocimetry. Unsteady Reynolds-averaged Navier–Stokes simulations were performed for a wide range of flow control parameters. The experimental and numerical results are used to understand the interaction between the jet and the passage flow. The benefit of the flow control on the cascade performance is weighted against the costs of the actuation by introducing an efficiency which takes the presence of the jets into account.

Analytical and Experimental Determination of Tip Clearance Effects in a High Work Turbine Rotor

1991 ◽  
Author(s):  
Jong-Shang Liu ◽  
George Minkkinen ◽  
Riccardo Bozzola
Keyword(s):  
Vortex Flow ◽  
Three Dimensional ◽  
Turbine Rotor ◽  
Tip Clearance ◽  
Experimental Investigations ◽  
Flow Angle ◽  
Blade Loading ◽  
Clearance Flow ◽  
Flow Phenomena ◽  
High Work

Analytical and experimental investigations were conducted to study important tip clearance flow phenomena, such as leakage vortex, flow underturning, and the effect of clearance flow on blade loading and losses. A three-dimensional Navier-Stokes code was modified to include a tip clearance model. A recently designed transonic high-work turbine rotor was used as a test case. Detailed measurements were made at rotor inlet and exit planes and compared to analytical results. The comparisons included important design features, such as exit total pressure and flow angle. For tip clearance calculation, the agreement with data was improved in the near-tip region compared to calculation without tip clearance. The clearance flow phenomena, leakage vortex, flow underturning, changing of blade loading, and loss distribution were predicted.

Three-Dimensional Flow Field in Highly Loaded Compressor Cascade

2014 ◽  
Vol 136 (10) ◽  
Author(s):  
Ch. Beselt ◽  
M. Eck ◽  
D. Peitsch
Keyword(s):  
Static Pressure ◽  
Vortex Breakdown ◽  
Three Dimensional ◽  
Horseshoe Vortex ◽  
Flow Structures ◽  
Compressor Cascade ◽  
Three Dimensional Flow ◽  
Time Resolved ◽  
Blade Loading ◽  
Passage Vortex

Within the present paper, a detailed experimental investigation is presented. The influence of blade loading on the development and interaction of secondary flow structures within an annular compressor stator cascade (CSC) is examined. Experimental results at 3% chord hub clearance were obtained at four different blade loadings. Included are blade and endwall flow visualization, time resolved measurements of the static pressure on the endwall and radial–circumferential hot-wire traverse measurements within the passage as well as five-hole probe traverse measurements at the inlet and the outlet of the passage. The experimentally obtained results give detailed insight on the effect of the incidence on the development and interaction of the clearance vortex, horseshoe vortex, and the passage vortex. Furthermore, it will be shown that a vortex breakdown of the clearance vortex occurs at higher loadings.

Experimental Analysis of Rotating Instability Using Hot Wire Triggered PIV and Wavelet Transform

2014 ◽  
Author(s):  
Georg Hermle ◽  
Martin Lawerenz
Keyword(s):  
Wavelet Transform ◽  
Temporal Resolution ◽  
Sampling Rate ◽  
Hot Wire ◽  
Mean Flow ◽  
Compressor Cascade ◽  
Time Resolved ◽  
Piv Measurements ◽  
Rotating Instability ◽  
Phase Angles

The authors present initial results of hot wire anemometry triggered PIV measurements of periodic effects in an annular compressor cascade. The investigations are focused on the unsteady effect of a rotating instability (RI) and are based on PIV measurements performed within the passage of a highly loaded annular compressor cascade. Simultaneously, hot wire measurements were conducted within the same passage. Post-processing the hot wire signal by means of the wavelet transform obtained the time resolved frequency spectrum as well as the time resolved phase angles. Such spectra allow filtering the PIV results to select only the results that feature the investigated effect of PI. The corresponding phase angles of the wavelet transform enable grouping the selected PIV results in phase classes. The average of each class gives the statistical mean flow field for the corresponding phase angle. Afterwards, the statistical mean period of the RI can be displayed by discrete ensemble averaged PIV results. The presented method improves the possible temporal resolution of PIV systems beyond their technical sampling rate. In the case presented, the statistical method leads to a temporal resolution corresponding to a sampling rate of 1.5 kHz, whereas the effective sampling rate of the PIV system used is 4 Hz. The possible resolution in time is only limited by the number of phase classes and accordingly by the number of PIV measurements.

Time-resolved measurements of sodium emission in the plume generated by laser ablation of myocardium tissue

2004 ◽  
Author(s):  
Hanriete P. de Souza ◽  
Egberto Munin ◽  
Carlos Eduardo de Vilhena Paiva ◽  
Leandro P. Alves ◽  
Marcela L. Redigolo ◽  
...  
Keyword(s):  
Laser Ablation ◽  
Time Resolved ◽  
Time Resolved Measurements
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