Stator-Rotor Interactions in a Transonic Compressor— Part 1: Effect of Blade-Row Spacing on Performance

2003 ◽  
Vol 125 (2) ◽  
pp. 328-335 ◽  
Author(s):  
Steven E. Gorrell ◽  
Theodore H. Okiishi ◽  
William W. Copenhaver
Keyword(s):  
Mass Flow Rate ◽  
Mass Flow ◽  
Flow Rate ◽  
Pressure Ratio ◽  
Axial Flow ◽  
Transonic Compressor ◽  
Blade Row ◽  
Spacing Variation ◽  
Stator Blade ◽  
Flow Compressor

Usually less axial spacing between the blade rows of an axial flow compressor is associated with improved efficiency. However, mass flow rate, pressure ratio, and efficiency all decreased as the axial spacing between the stator and rotor was reduced in a transonic compressor rig. Reductions as great as 3.3% in pressure ratio, and 1.3 points of efficiency were observed as axial spacing between the blade rows was decreased from far apart to close together. The number of blades in the stator blade-row also affected stage performance. Higher stator blade-row solidity led to larger changes in pressure ratio efficiency, and mass flow rate with axial spacing variation. Analysis of the experimental data suggests that the drop in performance is a result of increased loss production due to blade-row interactions. Losses in addition to mixing loss are present when the blade-rows are spaced closer together. The extra losses are associated with the upstream stator wakes and are most significant in the midspan region of the flow.

Stator-Rotor Interactions in a Transonic Compressor: Part 1 — Effect of Blade-Row Spacing on Performance

2002 ◽  
Author(s):  
Steven E. Gorrell ◽  
Theodore H. Okiishi ◽  
William W. Copenhaver
Keyword(s):  
Mass Flow Rate ◽  
Mass Flow ◽  
Flow Rate ◽  
Pressure Ratio ◽  
Axial Flow ◽  
Transonic Compressor ◽  
Blade Row ◽  
Spacing Variation ◽  
Stator Blade ◽  
Flow Compressor

Usually less axial spacing between the blade rows of an axial flow compressor is associated with improved efficiency. However, mass flow rate, pressure ratio, and efficiency all decreased as the axial spacing between the stator and rotor was reduced in a transonic compressor rig. Reductions as great as 3.3% in pressure ratio and 1.3 points of efficiency were observed as axial spacing between the blade-rows was decreased from far apart to close together. The number of blades in the stator blade-row also affected stage performance. Higher stator blade-row solidity led to larger changes in pressure ratio, efficiency, and mass flow rate with axial spacing variation. Analysis of the experimental data suggests that the drop in performance is a result of increased loss production due to blade-row interactions. Losses in addition to mixing loss are present when the blade-rows are spaced closer together. The extra losses are associated with the upstream stator wakes and are most significant in the mid-span region of the flow.

Numerical Simulation of Steady Air Injection Flow Control Effects on a Transonic Axial Flow Compressor

2012 ◽  
Vol 224 ◽  
pp. 352-357
Author(s):  
Islem Benhegouga ◽  
Ce Yang
Keyword(s):  
Mass Flow Rate ◽  
Mass Flow ◽  
Flow Rate ◽  
Pressure Ratio ◽  
Axial Flow ◽  
Leading Edge ◽  
Air Injection ◽  
Axial Flow Compressor ◽  
Blade Tip ◽  
Flow Compressor

In this work, steady air injection upstream of the blade leading edge was used in a transonic axial flow compressor, NASA rotor 37. The injectors were placed at 27 % upstream of the axial chord length at blade tip, the injection mass flow rate is 3% of the chock mass flow rate, and 3 yaw angles were used, respectively -20°, -30°, and -40°. Negative yaw angles were measured relative to the compressor face in opposite direction of rotational speeds. To reveal the mechanism, steady numerical simulations were performed using FINE/TURBO software package. The results show that the stall mass flow can be decreased about 2.5 %, and an increase in the total pressure ratio up to 0.5%.

Design and Internal Flow Analysis of a Ducted Contra-Rotating Axial Flow Fan

2014 ◽  
Author(s):  
Ali Mohammadi ◽  
Masoud Boroomand
Keyword(s):  
Mass Flow Rate ◽  
Mass Flow ◽  
Flow Rate ◽  
Pressure Ratio ◽  
Axial Flow ◽  
Optimum Operating ◽  
Axial Flow Fan ◽  
Design Algorithm ◽  
Flow Solver ◽  
Operating Points

This paper presents the design procedure of a ducted contra-rotating axial flow fan and investigates the flow behavior inside it using ANSYS CFX-15 flow solver. This study investigates parameters such as pressure ratio, inlet mass flow rate and efficiency in different operating points. This system consists of two rotors with an outer diameter of 434 mm and an inner diameter of 260 mm which rotate contrary to each other with independent nominal rotational speeds of 1300 rpm. Blades’ maximum thickness and rotational speeds of each rotor will be altered as well as the axial distance between the two rotors to investigate their effect on the overall performance of the system. Designed to deliver a total pressure ratio of 1.005 and a mass flow rate of 1.8 kg/s at nominal rotational speeds, this system proves to be much more efficient compared to the conventional rotor-stator fans. NACA-65 airfoils are used in this analysis with the necessary adjustments at each section. Inverse design method is used for the first rotor and geometrical constraints are employed for the second one to have an axial inlet and outlet flow without using any inlet or outlet guide vanes. Using free vortex swirl distribution method, characteristic parameters and the necessary data for 3D generation of this model are obtained. The appropriate grid is generated using ATM method in ANSYS TurboGrid and the model is simulated in CFX-15 flow solver by employing k-ε turbulence model in the steady state condition. Both design algorithm and simulation analysis confirm the high anticipated efficiency for this system. The accuracy of the design algorithm will be explored and the most optimum operating points in different rotational speed ratios and axial distances will be identified. By altering the outlet static pressure of the system, the characteristic map is obtained.

Experimental Investigation of Stepped Tip Gap Effects on the Performance of a Transonic Axial-Flow Compressor Rotor

1998 ◽  
Vol 120 (3) ◽  
pp. 477-486 ◽  
Author(s):  
D. W. Thompson ◽  
P. I. King ◽  
D. C. Rabe
Keyword(s):  
Mass Flow ◽  
Pressure Ratio ◽  
Axial Flow ◽  
Operating Conditions ◽  
Tip Clearance ◽  
Axial Flow Compressor ◽  
Transonic Compressor ◽  
Compressor Rotor ◽  
Percent Improvement ◽  
Flow Compressor

The effects of stepped-tip gaps and clearance levels on the performance of a transonic axial-flow compressor rotor were experimentally determined. A two-stage compressor with no inlet guide vanes was tested in a modern transonic compressor research facility. The first-stage rotor was unswept and was tested for an optimum tip clearance with variations in stepped gaps machined into the casing near the aft tip region of the rotor. Nine causing geometries were investigated consisting of three step profiles at each of three clearance levels. For small and intermediate clearances, stepped tip gaps were found to improve pressure ratio, efficiency, and flow range for most operating conditions. At 100 percent design rotor speed, stepped tip gaps produced a doubling of mass flow range with as much as a 2.0 percent increase in mass flow and a 1.5 percent improvement in efficiency. This study provides guidelines for engineers to improve compressor performance for an existing design by applying an optimum casing profile.

Experimental Investigation of Stepped Tip Gap Effects on the Performance of a Transonic Axial-Flow Compressor Rotor

1997 ◽  
Author(s):  
Donald W. Thompson ◽  
Paul I. King ◽  
Douglas C. Rabe
Keyword(s):  
Mass Flow ◽  
Pressure Ratio ◽  
Axial Flow ◽  
Operating Conditions ◽  
Tip Clearance ◽  
Axial Flow Compressor ◽  
Transonic Compressor ◽  
Compressor Rotor ◽  
Compressor Performance ◽  
Flow Compressor

The effects of stepped tip gaps and clearance levels on the performance of a transonic axial-flow compressor rotor were experimentally determined. A two-stage compressor with no inlet guide vanes was tested in a modern transonic compressor research facility. The first-stage rotor was unswept and was tested for an optimum tip clearance with variations in stepped gaps machined into the casing near the aft tip region of the rotor. Nine casing geometries were investigated consisting of three step profiles at each of three clearance levels. For small and intermediate clearances, stepped tip gaps were found to improve pressure ratio, efficiency, and flow range for most operating conditions. At 100% design rotor speed, stepped tip gaps produced a doubling of mass flow range with as much as a 2.0% increase in mass flow and a 1.5% improvement in efficiency. This study provides guidelines for engineers to improve compressor performance for an existing design by applying an optimum casing profile.

scholarly journals Temperature Rise in the Multistage Axial Flow Compressor During Rotating Stall and Surge

1988 ◽  
Author(s):  
Katerina Nácovská
Keyword(s):  
Mass Flow Rate ◽  
Mass Flow ◽  
Flow Rate ◽  
Axial Flow ◽  
Rotating Stall ◽  
Rotor Speed ◽  
Absolute Level ◽  
Axial Flow Compressor ◽  
Temperature Levels ◽  
Flow Compressor

An experimental investigation of rotating stall and surge was carried out on a four stage axial flow compressor. Results of flow and blade temperature measurements in the compressor are presented. Internal temperature levels during rotating stall and surge are considerably higher than those obtained during unstalled compressor operation. In the pure rotating stall regime, the temperature is almost identical in all compressor stages and depends only on rotor speed and mass flow rate. During surge, the highest temperature is found at the tip diameter prior to the first stage rotor. The absolute level depends on rotor speed, mass flow rate (i.e. throttle position) and on the number of compressor stages. A model of the temperature changes in the multistage compressor during the surge cycle has been derived from the experiments.

Parametric Study of Tip Injection in an Axial Flow Compressor Stage

2007 ◽  
Author(s):  
Gabriele Cassina ◽  
Behnam H. Beheshti ◽  
Albert Kammerer ◽  
Reza S. Abhari
Keyword(s):  
Mass Flow Rate ◽  
Mass Flow ◽  
Flow Rate ◽  
Rotor Blade ◽  
Axial Flow ◽  
Axial Flow Compressor ◽  
Stable Operating ◽  
Operating Margin ◽  
Tip Injection ◽  
Flow Compressor

Tip injection upstream of the rotor blade is a well-known technique for suppressing instabilities in axial compressors and recovering from a fully developed stall. In tip critical rotors, tip injection can effectively increase the blade loading and the stable operating margin of compressors by unloading the rotor tip. Compared to fully annular injection, discrete tip injection is better able to increase the compressor stability. This paper presents a numerical study of the effects of discrete upstream air injection on the stability of an axial flow compressor. Reynolds-averaged Navier-Stokes equations have been solved using ANSYS CFX with a k-epsilon turbulence model for three compressor blade passages. To validate the simulations, mass flow rate, pressure ratio, and efficiency at the compressor design point have been computed and compared to experimental data and results are in good agreement. For simulation of tip injection, 10 axisymmetric, but circumferentially discrete injectors, positioned at 50% of the blade axial chord upstream of the rotor blade leading edge, have been modelled. The ports are mounted on the casing and provide high-pressure jet of air at a 15° angle in the radial direction. To study the effects of injection, the compressor map at design speed has been compared for the models with and without injection. Results indicate that tip injection improves the compressor stability by unloading the rotor tip. Simulations show that by increasing the injection mass flow, the compressor stable operating margin can be improved. Simulations also predict optimum values for the injection port width-to-length ratio and the injection angle when the injection mass flow rate and area are kept constant. Further studies have been done to investigate the effect of the axial position of the injector.

Wetness Effect on Transonic Moist-Air Flow Through a Compressor Rotor

2018 ◽  
Author(s):  
Shota Moriguchi ◽  
Hironori Miyazawa ◽  
Takashi Furusawa ◽  
Satoru Yamamoto
Keyword(s):  
Mass Flow Rate ◽  
Mass Flow ◽  
Flow Rate ◽  
Pressure Ratio ◽  
Moist Air ◽  
Water Droplets ◽  
Significant Deterioration ◽  
Dry Air ◽  
Transonic Compressor ◽  
Compressor Rotor

In this study, we simulated moist-air flows through a 3-D transonic compressor rotor, NASA Rotor 37, to investigate the thermophysical effects of evaporation of water droplets on 3-D compressor aerodynamics. The obtained results indicated that the total pressure ratio increased in the moist-air cases when compared with dry-air case as a result of the cooling due to evaporation. While the choking mass-flow rate is almost identical for the dry-air case and the moist-air cases, the operating curve was shifted to nearly choked state in the moist-air cases. Besides this, unsteady flows were obtained at higher mass-flow rate in the moist-air cases when compared with the dry-air case. As a result, a significant deterioration in the operation was observed in the moist-air cases. This is due to the rapid and significant evaporation of water droplets after the passage shock. A secondary flow streaming radially outside toward the tip through the separated region intensified and contributed to a formation of large blockage around the tip region.

Application of Casing Circumferential Grooves to Counteract the Influence of Tip Clearance

2008 ◽  
Author(s):  
Victor Mileshin ◽  
Igor Brailko ◽  
Andrew Startsev
Keyword(s):  
Mass Flow Rate ◽  
Mass Flow ◽  
Flow Rate ◽  
Pressure Ratio ◽  
Leading Edge ◽  
Tip Clearance ◽  
Leakage Flow ◽  
Tip Leakage Flow ◽  
Blade Height ◽  
Transonic Compressor

Widening of surge margin of a transonic compressor stage is the main objective of the paper. This stage is a typical middle stage of a modern high pressure compressor (HPC) with decreased number of stages. Hot tip clearance of the stage being integrated into a six-stage HPC providing total pressure ratio π* HPC ≥ 12 and mass flow-rate < 16 kg/sec is estimated at 2.5 – 3% of blade height and is classified as a large tip clearance. In this paper experimental and 3D viscous numerical performances of the stage are obtained for two values of rotor tip clearance — equal to 0.76% (small size) and 2.66% (large size) of blade height. In doing so, tip clearance enlargement from 0.76% to 2.66% has been made by increase of casing (shroud) radius. This increase is manufactured as a circumferential trench (recess) with axial width 30% larger than rotor axial chord. Below this tip clearance is called “recessed” tip clearance. A distinguishing feature of leakage flow in case of large tip clearance is a formation of reversed flow near rotor casing. This backflow being intensified by throttling causes increase of incidence at the rotor leading edge and development of rotor stall. Casing treatments are intended to inhibit and delay the process. Among them circumferential grooves is the simplest casing treatment. Investigated in this paper casing circumferential grooves cover 82% of rotor axial chord. Numerical visualization of the near-casing streamlines demonstrates that tip leakage flow drains into the casing grooves giving rise to extended domains of positive axial velocity. Calculated mass flow-rate through groove’s cross-section demonstrates maximum over the rotor blade tip (flow into the groove) and minimum at mid-pitch (flow out of the groove). Amplitude of this variation depends on the groove location and stage throttling.

Active Flow Control for Increasing the Surge Margin of an Axial Flow Compressor

2006 ◽  
Author(s):  
M. Kefalakis ◽  
K. D. Papailiou
Keyword(s):  
Mass Flow Rate ◽  
Mass Flow ◽  
Flow Rate ◽  
Active Flow Control ◽  
Axial Flow ◽  
Axial Flow Compressor ◽  
Surge Margin ◽  
Pulsating Jet ◽  
Pulsating Jets ◽  
Flow Compressor

Steady and pulsating jets were used targeting to increase the surge margin of an axial flow compressor. In this experimental study, a rotating valve was built for generating pulsating jets and a number of pulsating jet actuators were installed on the compressor casing. Approximately 10% surge margin increase was obtained for a jet mass flow rate of less than 1% of the compressor mass flow rate. The active control mechanism is analyzed and the influence of each parameter is studied in an effort to quantify their relative influence and increase our understanding of the phenomenon.

Sign in / Sign up

Export Citation Format

Share Document