Efficiency improvement of regenerative pump using blade profile modification: Experimental study

2018 ◽  
Vol 233 (3) ◽  
pp. 448-455 ◽  
Author(s):  
J Nejad ◽  
A Riasi ◽  
A Nourbakhsh
Keyword(s):  
Experimental Study ◽  
Experimental Tests ◽  
Design Flow ◽  
Flow Coefficient ◽  
Low Flow ◽  
Impeller Blade ◽  
Profile Modification ◽  
Compact Size ◽  
Curved Blade ◽  
Regenerative Flow

Regenerative flow pump is a kind of turbomachine with the ability to generate high heads at relatively low flow rates. Despite having low hydraulic efficiency, regenerative pumps have found many applications in industries due to their simplicity, compact size, low manufacturing costs, and low specific speed. In this paper, an experimental study has been carried out to investigate the influence of impeller blade change on the performance of regenerative pump. To this end, the straight radial blades were changed to curved blades with the same inlet/outlet angles. Three forward curved blade impellers as well as straight radial blade impeller were designed and manufactured. Since the regenerative pump comply with the affinity laws, the results of experimental tests were expressed in nondimensional coefficients. The results showed that by increasing the blade angle to 10°, the efficiency increased and at higher blade angles of 30° and 50°, the efficiency decreased for all flow conditions. The best angle was obtained about 15° by curve fitting to the experimental data at the design flow coefficient.

scholarly journals Flow Pattern Analysis and Performance Improvement of Regenerative Flow Pump Using Blade Geometry Modification

2016 ◽  
Vol 2016 ◽  
pp. 1-16 ◽  
Author(s):  
J. Nejadrajabali ◽  
A. Riasi ◽  
S. A. Nourbakhsh
Keyword(s):  
Numerical Study ◽  
Design Flow ◽  
Flow Coefficient ◽  
Low Flow ◽  
Maximum Efficiency ◽  
Low Specific Speed ◽  
And Performance ◽  
Regenerative Flow ◽  
Inlet Angle ◽  
Flow Pump

Regenerative pump is a low specific speed and rotor-dynamic turbomachine capable of developing high heads at low flow rates. In this paper, a numerical study has been carried out in order to investigate the effect of blade angle on the performance of a regenerative pump. Two groups of impellers were employed. The first type has symmetric angle blades with identical inlet/outlet angles of ±10°, ±30°, and ±50° and the second group has nonsymmetric angle blades in which the inlet angle was set to 0° and six different angles of ±10°, ±30°, and ±50° were designed for the outlet of the blades. A total of 12 impellers, as well as primary radial blades impeller, were investigated in this study. The results showed that all forward blades have higher head coefficients than radial blades impeller at design flow coefficient. It was found that regenerative pumps with symmetric angle forward blades have better performance than other types. Also, it is worth mentioning that the highest head coefficient and efficiency occur at angle+10<β<+30of symmetric angle blades. It was found that the maximum efficiency occurs at angle of +15.5° by curve fitting to the data obtained from numerical simulations for symmetric angle forward blades.

Experimental Investigation and Characterization of the Rotating Stall in a High Pressure Centrifugal Compressor: Part II — Influence of Diffuser Geometry on Stage Performance

2002 ◽  
Author(s):  
G. Ferrara ◽  
L. Ferrari ◽  
C. P. Mengoni ◽  
M. De Lucia ◽  
L. Baldassarre
Keyword(s):  
Experimental Tests ◽  
Rotating Stall ◽  
Geometric Parameters ◽  
Flow Coefficient ◽  
Low Flow ◽  
Main Task ◽  
Stage Performance ◽  
The Impact ◽  
Prediction Criteria

Extensive research on centrifugal compressors has been planned. The main task of the research is to improve present prediction criteria coming from the literature with particular attention to low flow coefficient impellers (low width to radius ratios) where they are no more valid. Very little data has been published for this kind of stages, especially for the last stage configuration (with discharge volute). Many experimental tests have been planned to investigate different configurations. A simulated stage with a backward channel upstream, a 2D impeller with a vaneless diffuser and a constant cross section volute downstream constitute the basic configuration. Several diffuser types with different widths, pinch shapes and diffusion ratios were tested. The effect of geometric parameters on stage stability has been discussed inside part I of the present work; the purpose of this part of the work is to illustrate the effect of the same geometric parameters on stage performance and to quantify the impact of stability improvements on stage losses.

Reynolds Number and Roughness Effects on Turbocompressor Performance: Numerical Calculations and Measurement Data Evaluation

2020 ◽  
Author(s):  
Fabian Dietmann ◽  
Michael Casey ◽  
Damian M. Vogt
Keyword(s):  
Reynolds Number ◽  
Measurement Data ◽  
Theoretical Models ◽  
Design Flow ◽  
Flow Coefficient ◽  
Low Flow ◽  
Roughness Effects ◽  
Flow Channels ◽  
Compressor Performance ◽  
Low Flow Coefficient

Abstract Further validation of an analytic method to calculate the influence of changes in Reynolds number, machine size and roughness on the performance of axial and radial turbocompressors is presented. The correlation uses a dissipation coefficient as a basis for scaling the losses with changes in relative roughness and Reynolds number. The original correlation from Dietmann and Casey [6] is based on experimental data and theoretical models. Evaluations of five numerically calculated compressor stages at different flow coefficients are presented to support the trends of the correlation. It is shown that the sensitivity of the compressor performance to Reynolds and roughness effects is highest for low flow coefficient radial stages and steadily decreases as the design flow coefficient of the stage and the hydraulic diameter of the flow channels increases.

scholarly journals РЕЗУЛЬТАТЫ УСОВЕРШЕНСТВОВАНИЯ СТУПЕНИ ВЫСОКОНАГРУЖЕННОЙ ТУРБИНЫ НИЗКОГО ДАВЛЕНИЯ

2019 ◽  
pp. 30-37
Author(s):  
Игорь Федорович Кравченко ◽  
Сергей Александрович Хомылев
Keyword(s):  
Flow Separation ◽  
Wedge Angle ◽  
Operating Conditions ◽  
Design Flow ◽  
Flow Coefficient ◽  
Low Flow ◽  
Energy Losses ◽  
Suction Surface ◽  
Experimental Development ◽  
Leading Edges

One of the characteristic features of high loaded low-pressure turbine (LPT) with a low flow coefficient is the high-level flow deflection in the blade rows, which have sufficiently thin and strongly curved cross-section profiles. Such profiles are very sensitive to off-design flow angles, especially to positive incidence. Therefore, the effectiveness of a high loaded LPT strongly depends on the working conditions. At the same time, for various reasons, in the process of research tests or operating the engine, the operating conditions may differ greatly from the design ones. Therefore, the creation of a robust LPT design is an actual task. The article considers the computational approbation of the method of increasing the resistance to large off-design angles of attack of vane and blade rows of the intermediate stage of a high loaded LPT of an experimental engine by changing the shape of the leading edges. The turbine was previously tested as part of a full-scale engine, where it was determined that the operating conditions of the LPT and its efficiency are significantly different from the calculated ones. Numerical (CFD) analysis of the flow showed that one of the reasons for the low efficiency is the large angles of attack on the vane and blade rows of the second stage, which lead to the flow separation and an increase of the energy losses coefficients at final. The modernization of the profiles was carried out by reducing the radius and a local increase of the leading edges wedge angle without changing the basic profiles. According to the calculation results, it was allowed to significantly improve the stream. The intensity of the flow deceleration behind the shock wave at the point of transition from the circumference of the edge to the suction surface was reduced, this made it possible to eliminate or reduce the intensity of the flow separation in the vane row and significantly reduce the energy losses coefficient. A more favorable flow was also achieved in the blade row, where a slight decrease in the losses coefficient was also obtained. As a result, the efficiency of the stage and the whole LPT was increased at the off-design operating conditions. This approach can be recommended both to increase the efficiency of the turbine at the experimental development, and when designing new turbines to increase their robustness.

Effects of Inlet Pressure Distortion on the Performance and Flow Field of a Centrifugal Compressor at Off-Design Conditions

2012 ◽  
Author(s):  
N. Sitaram ◽  
M. Govardhan ◽  
K. V. Murali
Keyword(s):  
Flow Field ◽  
Centrifugal Compressor ◽  
Total Pressure ◽  
Static Pressure ◽  
Design Flow ◽  
Flow Coefficient ◽  
Low Flow ◽  
Performance Measurements ◽  
Perforated Sheet ◽  
Sector Angle

The present paper presents experimental results on the effects of inlet total pressure distortion on the performance and flow field of a centrifugal compressor. The total pressure at inlet is artificially distorted by means of a perforated sheet, which is supported by a support mesh. A total of eleven configurations, including clean inlet configuration, are tested. Performance measurements and impeller inlet and exit flow studies at three flow coefficients, one near design flow coefficient, one below design flow coefficient and one above design flow coefficient, are carried out. The present paper presents and discusses results at off-design flow coefficients and the effects of stage loading on the distortion effects are presented. A new parameter, Distortion Index (DI) is introduced. As DI increases, the mass averaged total pressure at exit stations decreases. Distortion sector angle of 60° having the lowest total pressure is found to be the critical sector for circumferential distortion configurations. As the Distortion Correlation parameter, DC(60) increases, the mass averaged total pressure for circumferential distortion configuration decreases, except in the case of low flow coefficient where DC(60) is nearly constant. DC(60) also increases with sector angle. The static pressure normalized with static pressure for clean inlet decreases as the distortion sector angle is increased. Distortion attenuates the static pressure as the flow passes through the vaneless diffuser. The attenuation increases with the distortion sector angle.

Modified Surge in an Axial Flow Compressor

1992 ◽  
Author(s):  
Libor Půst
Keyword(s):  
Experimental Study ◽  
Unsteady Flow ◽  
Axial Flow ◽  
Rotating Stall ◽  
Design Flow ◽  
Flow Coefficient ◽  
Axial Flow Compressor ◽  
Flow Compressor

This paper deals with an experimental study of the unsteady flow in a multistage axial-flow compressor with a high design flow coefficient (p = 1.2) at rpm lower than the design ones. A detailed description of the rotating stall during the so-called “modified surge” is given. In this surge type the rotating stall exists during all the surge cycle, in contradistinction of classic surge, when the rotating stall exists only in a part of the surge cycle.

Numerical Investigation of Effects of Different Hub Tip Diameter Ratios on Aerodynamic Performance of Single Shaft Multistage Centrifugal Compression Systems

2012 ◽  
Author(s):  
Thomas Ceyrowsky ◽  
Andre Hildebrandt
Keyword(s):  
Characteristic Curve ◽  
Design Flow ◽  
Flow Coefficient ◽  
Low Flow ◽  
Design Stage ◽  
Daily Routine ◽  
Stage Design ◽  
Design Point ◽  
Thermodynamic Behaviour ◽  
The Impact

Regarding industrial centrifugal compressors in single shaft design, different configurations with e.g. varying numbers of stages or diverse circumferential speeds, necessitate different shaft diameters. Thus the application of impellers with different hub/tip ratios (dh/d2) is daily routine in industrial practice. Increasing hub/tip ratio leads to higher radii and therefore higher relative speeds, to a reduction in the impeller’s meridional length and hence more rapid diffusion, and to a sharper bending from axial to radial direction. In this paper the impact of hub/tip ratio on stage performance is investigated for three different centrifugal compressor stages, by steady state CFD-calculations. The hub/tip ratio is varied between 0.325 < dh/d2 < 0.45. The relation between design stage flow coefficient and hub/tip ratio is also analysed, both at design and off-design. Thermodynamic behaviour is assessed by 1D-data and also by the investigation of secondary flow features. The current analysis shows, that hub/tip ratio’s influence on characteristics is strongly dependent on the particular stage’s design flow coefficient and circumferential Mach-Number. Increasing a high flow stage’s hub/tip ratio is shown to decrease peak efficiency as well, as to limit the operating range. On the contrary, in case of a low flow stage, design point efficiency is hardly affected, but the characteristic curve is tilted around design point, by applying a different hub/tip ratio. However severity of hub/tip ratio’s impact on thermodynamic behaviour shows to decrease together with stage design flow coefficient.

Analysis and Redesign of the Stationary Components for a Low Flow Coefficient Centrifugal Compressor Stage

2009 ◽  
Author(s):  
Zhiheng Wang ◽  
Guang Xi
Keyword(s):  
Centrifugal Compressor ◽  
Design Flow ◽  
Flow Coefficient ◽  
Low Flow ◽  
Meridional Plane ◽  
Compressor Stage ◽  
Centrifugal Compressor Stage ◽  
Lower Stage ◽  
Wide Range ◽  
Low Flow Coefficient

A low flow coefficient centrifugal compressor stage is characterized by the small relative outlet width, and is often one of the latter stages in the multistage compressor. The low flow coefficient stage is known to give lower stage efficiency in comparison with the conventional stage, which still leaves much more space to be improved with modern tools such as CFD techniques. In the paper the flow in a CO2 centrifugal compressor stage with a low design flow coefficient of 0.008 is simulated based on the 3D viscous CFD codes. The analysis shows the impeller gives a favorable performance over a wide range of low flow coefficient, but the high losses exist in the stationary components and this incurs the poor performance of the whole stage. In this case, the diffuser, the return channel and the meridional plane are redesigned. The redesigned stage has distinct improvements on the performance and the flow structure.

Influence of a Stability Control Device on the Performance of a Cavitating Water Pump Inducer

2014 ◽  
Author(s):  
R. Lundgreen ◽  
D. Maynes ◽  
S. Gorrell ◽  
K. Oliphant
Keyword(s):  
Fluid Dynamic ◽  
Stability Control ◽  
Control Device ◽  
Design Flow ◽  
Flow Coefficient ◽  
Low Flow ◽  
Stable Operation ◽  
Dynamic Simulations ◽  
The Stability ◽  
Rotordynamic Forces

An inducer performance has been explored with and without the implementation of a stability control device. Multiphase, time-accurate computational fluid dynamic simulations have been conducted at the design flow coefficient and at two low off-design flow coefficients. At the design flow coefficient, the inducer performance was similar with and without the stability control device. At low flow coefficients, the inducer without the stability control device exhibited significant cavitation instabilities, which led to high rotordynamic forces on the inducer blades. When the stability control device was incorporated into the inducer design, nearly all of the cavitation instabilities were suppressed at low flow coefficients and the rotordynamic forces were reduced by more than an order of magnitude. Stable operation at flow coefficients far below the design value leads to a significant increase in the suction performance of the inducer, allowing pumps to operate at lower inlet pressures.

CFD Applications to Industrial Centrifugal Compressor Design

2002 ◽  
Author(s):  
Andrea Arnone ◽  
Duccio Bonaiuti ◽  
Paolo Boncinelli ◽  
Mirco Ermini ◽  
Alberto Milani ◽  
...  
Keyword(s):  
Three Dimensional ◽  
Experimental Tests ◽  
Computational Procedure ◽  
Flow Coefficient ◽  
Low Flow ◽  
Centrifugal Impeller ◽  
Geometrical Parameters ◽  
Future Design ◽  
Numerical Predictions ◽  
The Impact

The aerodynamic redesign of an industrial transonic centrifugal impeller by means of CFD techniques is presented here. The computational procedure was validated by comparing numerical predictions of efficiency and work input coefficient to data from experimental tests on two different typologies of impellers: a low flow coefficient subsonic radial impeller and a high flow coefficient one. Three–dimensional, fully viscous computations were used to investigate the transonic impeller aerodynamic performance in terms of both the characteristic curves and details of the flow structure, suggesting possible improvements in the design. In order to standardize the redesign process of 3D impellers, a number of geometrical parameters, capable of describing the main features of the geometry, were identified. The original configuration was modified by varying the values of such parameters, and the impact of changes was assessed by means of 3D computations. As a result, the designer would be able to recognize which parameters have greater influence, and understand the physical effect of each change. This made it possible to establish some design rules to be exploited in future design processes.

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