Modelling of Multistage Axial Compressor using Successive Diffusers with Velocity Sources: Part II–Unsteady Results

2018 ◽  
Author(s):  
Abhishek Mishra ◽  
Yedidia Neumeier ◽  
JVR Prasad ◽  
Darrell K. James
Keyword(s):  
Axial Compressor ◽  
Multistage Axial Compressor

scholarly journals Stator re-stagger optimization in multistage axial compressor

2021 ◽  
Author(s):  
Jinguang Yang ◽  
Min Zhang ◽  
Cheng Peng ◽  
Michele Ferlauto ◽  
Yan Liu
Keyword(s):  
Axial Compressor ◽  
Multistage Axial Compressor

scholarly journals Experimental Assessment of Fouling Effects in a Multistage Axial Compressor

2020 ◽  
Vol 197 ◽  
pp. 11007
Author(s):  
Nicola Casari ◽  
Michele Pinelli ◽  
Pier Ruggero Spina ◽  
Alessio Suman ◽  
Alessandro Vulpio
Keyword(s):  
Gas Turbine ◽  
Axial Compressor ◽  
Operating Conditions ◽  
Rotor Blades ◽  
Small Scale ◽  
Performance Loss ◽  
Machine Performance ◽  
Internal Surfaces ◽  
Analysis Package ◽  
Multistage Axial Compressor

The study of the adhesion of micro sized particles to gas turbine internal surfaces, commonly known as gas turbine fouling, has gained increasing attention in the last years due to its dramatic effect on machine performance and reliability. On-field fouling analysis is mostly related to visual inspections during overhaul and/or programmed stops, which are performed, in particular, when gas turbine performance degradation falls under predetermined thresholds. However, these analyses, even if performed in the most complete as possible way, are rarely (or never) related to the conditions under which the gas turbine contamination takes place since the affecting parameters are difficult or even impossible to be adequately monitored. In the present work, a small scale multistage axial compressor is used to experimentally simulate the fouling phenomenon. The test rig allows the accurate control of the most relevant operating parameters which influence the fouling phenomenon. The compressor performance loss due to particle contamination has been quantitatively assessed. Soot particles appear stickier, especially in the presence of high humidity, and represent the most harmful operating conditions for the compressor unit. The deposits on the stator vanes and the rotor blades have been detected and post-processed, highlighting the most affected regions of each compressor stage employing an image analysis package tool.

Experimental Investigation of a Stall Prediction System Using a Transonic Multistage Compressor

2007 ◽  
Author(s):  
Tomofumi Nakakita ◽  
Masahiro Kurosaki ◽  
Yukio Kamiyoshihara
Keyword(s):  
Axial Compressor ◽  
Prediction System ◽  
Test Results ◽  
Stall Margin ◽  
Pressure Transducers ◽  
Stator Vane ◽  
Multistage Compressor ◽  
Stall Warning ◽  
Stall Control ◽  
Multistage Axial Compressor

This paper describes the test results of a stall prediction system using a transonic multistage axial compressor. The test results show that there is a clear relationship between the stall margin and the stall-warning index measured at the first stage. The stall warning index is derived from auto correlation of casing wall pressure signals above the rotor tip. In the tests, the compressor installed with pressure transducers on the casing wall near the leading edges of the first three rotors was forced to stall while operating at a constant speed by closing the discharge valve. The test results where the stator vane settings of the first three stages were changed show that load distribution among stages does not have significant effects on the stall margin vs. stall-warning index relationship. Using some smoothing technique, undesired time variation of the stall-warning index can be reduced to the level necessary for practical active stall control with allowable response time delay.

Leakage Effects in the Rotor Tip-Clearance Region of a Multistage Axial Compressor: Part 2 — Numerical Modelling

1998 ◽  
Author(s):  
E. S. Politis ◽  
K. C. Giannakoglou ◽  
K. D. Papailiou
Keyword(s):  
Axial Compressor ◽  
Tip Clearance ◽  
Navier Stokes ◽  
Computational Domain ◽  
Loose Coupling ◽  
Tip Clearance Flow ◽  
Clearance Flow ◽  
Flow Effects ◽  
Multistage Axial Compressor ◽  
Asme Paper

Innovative measurements of tip-clearance flow for the 3rd stage rotor embedded in a four stage Low-Speed Research Compressor are presented in the companion ASME paper. Here, in Part 2, the rotor flow is numerically simulated through a Navier-Stokes solver implementing the k-ε turbulence model. The 3rd stage rows are considered as discrete parts of the same computational domain and the flow in each one of them is treated as steady in the corresponding system of reference. An iterative, though loose, coupling between the rotor exit and the stator inlet is established by artificially increasing the inter-row distance. To model tip-clearance flow effects with sufficient accuracy, a two-block grid system per row is used. Comparisons with measurements published in Part 1 for the average flow quantities at the exit of both rows are presented. Row patterns close to the rotor tip-clearance region are illustrated.

scholarly journals Application of a Split-Fiber Probe to Velocity Measurement in the NASA Research Compressor

2003 ◽  
Author(s):  
J. Lepicovsky
Keyword(s):  
Averaging Method ◽  
Axial Compressor ◽  
Local Heat Transfer ◽  
Local Heat ◽  
Ensemble Averaging ◽  
Test Program ◽  
Fiber Probe ◽  
Velocity Magnitude ◽  
Velocity Characteristic ◽  
Multistage Axial Compressor

A split-fiber probe was used to acquire unsteady data in a research compressor. The probe has two thin films deposited on a quartz cylinder 200 μm in diameter. A split-fiber probe allows simultaneous measurement of velocity magnitude and direction in a plane that is perpendicular to the sensing cylinder, because it has its circumference divided into two independent parts. Local heat transfer considerations indicated that the probe direction characteristic is linear in the range of flow incidence angles of ±35 dg. Calibration tests confirmed this assumption. Of course, the velocity characteristic is nonlinear as is typical in thermal anemometry. The probe was used extensively in the NASA GRC low-speed, multistage axial compressor, and worked reliably during a test program of several months duration. The velocity and direction characteristics of the probe showed only minute changes during the entire test program. An algorithm was developed to decompose the probe signals into velocity magnitude and velocity direction. The averaged unsteady data were compared with data acquired by pneumatic probes. An overall excellent agreement between the averaged data acquired by a split-fiber probe and a pneumatic probe boosts confidence in the reliability of the unsteady content of the split-fiber probe data. To investigate the features of unsteady data, two methods were used: ensemble averaging and frequency analysis. The velocity distribution in a rotor blade passage was retrieved using the ensemble averaging method. Frequencies of excitation forces that may contribute to high cycle fatigue problems were identified by applying a fast Fourier transform to the absolute velocity data.

Considerations for Using 3D Pneumatic Probes in High Speed Axial Compressors

2002 ◽  
Author(s):  
Simon Coldrick ◽  
Paul Ivey ◽  
Roger Wells
Keyword(s):  
High Speed ◽  
Three Dimensional ◽  
Axial Compressor ◽  
Pressure Probe ◽  
Probe Type ◽  
Calibration Data ◽  
Axial Compressors ◽  
Close Proximity ◽  
Multistage Axial Compressor ◽  
Preparatory Work

This paper describes preparatory work towards three dimensional flowfield measurements downstream of the rotor in an industrial, multistage, axial compressor, using a pneumatic pressure probe. The probe is of the steady state four hole cobra probe type. The design manufacture and calibration of the probe is described. CFD calculations have been undertaken in order to assess the feasability of using such a probe in the high speed compressor environment where space is limited. This includes effects of mounting the probe in close proximity to the downstream stator blades and whether it is necessary to adjust the calibration data to compensate for these effects.

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