An Experimental Investigation of the Non-Steady Flow Characteristics of a Centrifugal Compressor

1965 ◽  
Vol 180 (1) ◽  
pp. 641-672 ◽  
Author(s):  
R. S. Benson ◽  
A. Whitfield
Keyword(s):  
Experimental Investigation ◽  
Steady Flow ◽  
Mass Flow ◽  
Centrifugal Compressor ◽  
Flow Characteristics ◽  
Flow Conditions ◽  
Rotary Valve ◽  
Low Frequencies ◽  
Pipe System ◽  
Compressor Efficiency

The results are given of an experimental investigation of the flow characteristics of a centrifugal compressor under non-steady flow conditions. The compressor delivered air against a rotary valve with a tee branch located in the pipe system between the compressor and the rotary valve. By varying the areas of a nozzle located at the branch end and orifices in the rotary valve a range of flow conditions could be explored. The tests showed that the surge point was displaced to a point of greater mass flow (thus reducing the flow range of the compressor); the magnitude of the displacement depended on the frequency and amplitude of the pressure pulses. Except for small fluctuations in pressure the overall compressor efficiency was reduced for all the test conditions. The flow characteristic of the compressor, as represented by the pressure-mass flow curves, were displaced under all conditions of pulsating flow, the greatest deviation from steady flow characteristics occurring with largest fluctuations in rotary valve area and at low frequencies.

A particle image velocimetry study on the pulsatile flow characteristics in straight tubes with an asymmetric bulge

2000 ◽  
Vol 214 (5) ◽  
pp. 655-671 ◽  
Author(s):  
S C M Yu ◽  
J B Zhao
Keyword(s):  
Particle Image Velocimetry ◽  
Steady Flow ◽  
Pulsatile Flow ◽  
Flow Condition ◽  
Particle Image ◽  
Flow Characteristics ◽  
Reynolds Numbers ◽  
Working Fluid ◽  
Flow Conditions ◽  
Image Velocimetry

Flow characteristics in straight tubes with an asymmetric bulge have been investigated using particle image velocimetry (PIV) over a range of Reynolds numbers from 600 to 1200 and at a Womersley number of 22. A mixture of glycerine and water (approximately 40:60 by volume) was used as the working fluid. The study was carried out because of their relevance in some aspects of physiological flows, such as arterial flow through a sidewall aneurysm. Results for both steady and pulsatile flow conditions were obtained. It was found that at a steady flow condition, a weak recirculating vortex formed inside the bulge. The recirculation became stronger at higher Reynolds numbers but weaker at larger bulge sizes. The centre of the vortex was located close to the distal neck. At pulsatile flow conditions, the vortex appeared and disappeared at different phases of the cycle, and the sequence was only punctuated by strong forward flow behaviour (near the peak flow condition). In particular, strong flow interactions between the parent tube and the bulge were observed during the deceleration phase. Stents and springs were used to dampen the flow movement inside the bulge. It was found that the recirculation vortex could be eliminated completely in steady flow conditions using both devices. However, under pulsatile flow conditions, flow velocities inside the bulge could not be suppressed completely by both devices, but could be reduced by more than 80 per cent.

scholarly journals Ballast Flow Characteristics of Discharging Pipeline in Shield Slurry System

2019 ◽  
Vol 9 (24) ◽  
pp. 5402
Author(s):  
Yang Wang ◽  
Yimin Xia ◽  
Xuemeng Xiao ◽  
Huiwang Xu ◽  
Peng Chen ◽  
...  
Keyword(s):  
Mass Flow Rate ◽  
Mass Flow ◽  
Flow Rate ◽  
Flow Characteristics ◽  
Slurry Flow ◽  
Volumetric Concentration ◽  
Mass Percentage ◽  
Pipe System ◽  
Pipeline Wall ◽  
Slurry Flow Rate

We adopted two-way coupling of discrete and finite elements to examine the non-spherical ballast flow characteristics in a slurry pipe system during a shield project. In the study, we considered the slurry rheological property and the flake shape of the ballast. A ballast size between 17 and 32 mm under different slurry flow rates and ballast volumetric concentration conditions was investigated for determining the law through which the mass flow rate, detained mass percentage, and ballast distribution state are influenced. The results indicate that increasing slurry flow rate and the ballast volumetric concentration increase the mass flow rate; the influence of the latter is stronger. Increases in both in the slurry flow rate and the ballast volumetric concentration can reduce the detained mass percentage in the slurry discharging pipeline, whereas increasing the ballast size has the opposite effect. The increase in both the slurry flow rate and the ballast size changes the ballast motion state. Experiments verified the numerical lifting model of the ballast in the vertical pipeline. The measurements of the actual pipeline wall thickness verified that the simulation results regarding the ballast distribution were accurate.

3-D Time Domain Unsteady Computation of Rotating Instability in Steam Turbine Last Stage

2012 ◽  
Author(s):  
L. Y. Zhang ◽  
L. He ◽  
H. Stüer
Keyword(s):  
Mass Flow ◽  
Large Scale ◽  
Flow Behavior ◽  
Pressure Ratio ◽  
Flow Characteristics ◽  
Steam Turbines ◽  
Flow Conditions ◽  
Frequency Pattern ◽  
Last Stage ◽  
Rotating Instability

The rotating instability phenomenon in a last stage of steam turbines at low mass flow conditions has been previously identified experimentally. Recently, the rotating instability has also been numerically studied in a whole annulus domain on 2D blade sections. In the present work, 3D simulations of unsteady flows are carried out on two model steam turbines over a range of mass flow conditions. The pressure-ratio volume-flow characteristics in rotor row tip region under different flow conditions are well captured in the computations in comparison with the experiment. The effect of blade scaling is examined to identify the influence of changing blade counts for a circumferential domain reduction, showing relatively small effects on the overall performance characteristics. The present 3D unsteady solutions on a reduced multi-passage domain have been able to predict a rotating instability in the rotor blade tip region, in accord with the corresponding experiment. Further Fourier analysis is carried out to examine the frequency pattern and spatial modal features. The 3D flow behavior is highlighted by comparison between the 3D and 2D calculations. The present results seem to suggest that the rotating instability onset in the rotor tip region is largely independent of the large scale flow separation in the downstream diffusor.

Performance Characteristics of a Centrifugal Compressor with Air Injection

1973 ◽  
Vol 187 (1) ◽  
pp. 425-434 ◽  
Author(s):  
J. D. Ledger ◽  
R. S. Benson ◽  
H. Furukawa
Keyword(s):  
Mass Flow ◽  
Centrifugal Compressor ◽  
Total Mass ◽  
Pressure Ratio ◽  
Flow Characteristics ◽  
Performance Characteristics ◽  
Air Injection ◽  
Delivery Pressure ◽  
Mass Flow Rates ◽  
The Right

The parameters which influence the performance characteristics of centrifugal compressors with air injection through nozzles at the rotor tip are developed using both dimensional analysis and a simple model. Experiments on a small centrifugal compressor show that the injection air pressure is the main influence on the overall performance such as excess torque, increased delivery pressure and increased delivery flow. With air injection the pressure-mass flow characteristics are displaced to the right with surge occurring at increased total mass flow rates and the overall pressure ratio across the compressor is increased for the same total mass flow.

Effect of a volute on the unsteady flow in the vane diffuser of a centrifugal compressor

2016 ◽  
Vol 230 (8) ◽  
pp. 773-791 ◽  
Author(s):  
Gong W Qi ◽  
X Hong Zhang
Keyword(s):  
Mass Flow ◽  
Centrifugal Compressor ◽  
Total Pressure ◽  
Pressure Ratio ◽  
Operating Conditions ◽  
High Mass ◽  
Flow Conditions ◽  
Asymmetric Component ◽  
Unsteady Loading ◽  
Vane Diffuser

A volute is the only circumferential asymmetric component in a centrifugal compressor, and thus, it should account for the circumferential asymmetry of the flow in a vane diffuser. This study performs a transient numerical analysis to investigate the effect of a volute on the flow in the vane diffuser of a centrifugal compressor under three operating conditions (near-stall, middle, and high mass flow). We compare numerical and experimental performance of the compressor, including polytropic efficiency, total pressure ratio, and unsteady pressure on a diffuser vane. The numerical scheme is proven valid owing to the fact that the numerical and experimental results considerably agree well with each other. Under middle and high mass flow conditions, the time-averaged static pressure recovery and the total pressure loss coefficients for all the diffuser passages indicate that the performance of the passages near and upstream of the volute tongue is affected negatively by the volute, whereas that of the passages downstream of the volute tongue is less affected. Under near-stall condition, the performance of all the passages is disturbed, and the diffuser passage marked as DP 3 demonstrates the worst performance. Investigation on the time-averaged aerodynamic forces, loading, and pressure on the vanes yields results that are consistent with those of the investigation on the performance of the passages. The harmonics with 0.5 fb and fb, which are included in the unsteady loading and pressure on the pressure and suction sides of the vanes, are dominant, where fb is the impeller main and splitter blades passing frequency. Their amplitude values increase as mass flow deviates from the middle mass flow condition. Under middle and high mass flow conditions, the harmonic with 0.5 fb is affected more negatively because of the larger amplitude on the vanes near and upstream of the volute tongue than those downstream, whereas the harmonic with fb is less affected by the volute. Under the near-stall condition, the transient vorticity fields along with the harmonics of 0.5 fb and fb are investigated to evaluate the performance of the diffuser passages. DP 3, which is located at approximately 90° downstream of the volute tongue, suffers the strongest flow deterioration and is inferred to stall first. Further researches for designing more matching diffuser/volute combination will be performed by referring this study.

Performance Characteristics of a Centrifugal Compressor with Air Injection

1973 ◽  
Vol 187 (1) ◽  
pp. 425-434 ◽  
Author(s):  
J. D. Ledger ◽  
R. S. Benson ◽  
H. Furukawa
Keyword(s):  
Mass Flow ◽  
Centrifugal Compressor ◽  
Total Mass ◽  
Pressure Ratio ◽  
Flow Characteristics ◽  
Performance Characteristics ◽  
Air Injection ◽  
Delivery Pressure ◽  
Mass Flow Rates ◽  
The Right

The parameters which influence the performance characteristics of centrifugal compressors with air injection through nozzles at the rotor tip are developed using both dimensional analysis and a simple model. Experiments on a small centrifugal compressor show that the injection air pressure is the main influence on the overall performance such as excess torque, increased delivery pressure and increased delivery flow. With air injection the pressure-mass flow characteristics are displaced to the right with surge occurring at increased total mass flow rates and the overall pressure ratio across the compressor is increased for the same total mass flow.

Effect of End Plates on the Performance of an Impulse Turbine for Wave Energy Conversion

2007 ◽  
Author(s):  
Toshiaki Setoguchi ◽  
Manabu Takao ◽  
Kenji Kaneko ◽  
Shuichi Nagata ◽  
Kazutaka Toyota
Keyword(s):  
Experimental Investigation ◽  
Energy Conversion ◽  
Steady Flow ◽  
Wave Energy ◽  
Model Testing ◽  
Wave Energy Conversion ◽  
Flow Conditions ◽  
Impulse Turbine ◽  
End Plate ◽  
Plate Size

The objective of this paper is to present the effect of end plate on the performances of the impulse turbine for wave energy conversion by experimental investigation. The experiments have been performed by model testing under steady flow conditions in the study. And then, the performances of the impulse turbine with end plates have been compared with those of the original impulse turbine, i.e., the impulse turbine without end plate. As a result, it is found that the characteristics of the impulse turbine with end plates are superior to those of the original impulse turbine. Furthermore, the effects of end plate size and penetration on the turbine characteristics have been clarified in the study.

An experimental investigation of mass flow characteristics of laval nozzles with transversal injection through an annular slot in the side wall

1992 ◽  
Vol 18 (1) ◽  
pp. 35-39
Author(s):  
B.A. Gabaraev ◽  
E.K. Karasyev ◽  
O.Yu Novoselsky ◽  
S.Z. Lutovinov ◽  
L.K. Tickhonenko ◽  
...  
Keyword(s):  
Experimental Investigation ◽  
Mass Flow ◽  
Flow Characteristics ◽  
Side Wall ◽  
Annular Slot ◽  
Laval Nozzles
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