Design and Analysis of Energy-Efficient Low-Flow Centrifugal Compressors

2020 ◽  
Vol 142 (8) ◽  
Author(s):  
Cheng Xu ◽  
Lei Chen ◽  
Ryoichi S. Amano
Keyword(s):  
Flow Coefficient ◽  
Low Flow ◽  
Design Strategies ◽  
Design Features ◽  
Centrifugal Compressors ◽  
Design Studies ◽  
Low Specific Speed ◽  
Specific Speed ◽  
And Performance ◽  
Low Flow Coefficient

Abstract With the increasing demands of energy-saving from industries, the low-flow coefficient and low specific speed centrifugal compressors have gained more attention. The design of this type of compressor faced many challenges, for example, high secondary flow losses, high tip leakage losses, and low exit width based on a Reynolds number. The design also lacks a reliable database for preliminary studies. The impeller design studies were limited. Most designs for low-flow coefficient and low specific speed compressor follow the traditional methods. This paper presents design studies and discusses some unique design features to improve performance of this type of compressor. The detail computational fluids dynamics (CFD) results are presented to demonstrate the success of the design strategies. A prototype compressor for fuel cell applications was built, and performance tests were performed. The test results are compared with those of the computational analysis, and the agreement is reasonably satisfactory. The compressor meets the customer's performance goals. The design features can be used for future low-flow coefficient and low specific speed centrifugal compressor design.

Experimental Investigation and Performance Analysis of Six Low Flow Coefficient Centrifugal Compressor Stages

1995 ◽  
Vol 117 (4) ◽  
pp. 585-592 ◽  
Author(s):  
J. Paroubek ◽  
V. Cyrus ◽  
J. Kyncˇl
Keyword(s):  
Development Program ◽  
Rotating Stall ◽  
Flow Coefficient ◽  
Low Flow ◽  
Vaneless Diffuser ◽  
Test Rig ◽  
Disk Friction ◽  
Return Channel ◽  
And Performance ◽  
Low Flow Coefficient

Some results of a research and development program for centrifugal compressors are presented. Six-stage configurations with low flow coefficient were tested. The stages had channel width parameter b2/D2 = 0.01 and 0.03. For each value of the width parameter, three different impellers with inlet hub to outlet diameter ratio do/D2 = 0.3, 0.4, and 0.5 were designed. Test rig, instrumentation, and data analysis are described. Special attention was devoted to probe calibrations and to evaluation of the leakage, bearing, and disk friction losses. Aerodynamic performance of all tested stages is presented. Slip factors of impellers obtained experimentally and theoretically are compared. Losses in both vaneless diffuser and return channel with deswirl vanes are discussed. Rotating stall was also investigated. Criteria for stall limit were tested.

scholarly journals Experimental Investigation and Performance Analysis of Six Low Flow Coefficient Centrifugal Compressor Stages

1994 ◽  
Author(s):  
J. Paroubek ◽  
V. Cyrus ◽  
J. Kyncl
Keyword(s):  
Rotating Stall ◽  
Development Programme ◽  
Diameter Ratio ◽  
Flow Coefficient ◽  
Low Flow ◽  
Vaneless Diffuser ◽  
Test Rig ◽  
Return Channel ◽  
And Performance ◽  
Low Flow Coefficient

Some results of a research and development programme for centrifugal compressors are presented. Six stage configurations with low flow coefficient were tested. The stages had channel width parameter bo/D2=0.01 and 0.03. For each value of the width parameter three different impellers with inlet hub to outlet diameter ratio do/D2=0.3, 0.4 and 0.5 were designed. Test rig, instrumentation and data analysis are described. Special attention was devoted to probe calibrations and to evaluation of the leakage, bearing and disc friction losses. Aerodynamic performance of all tested stages is presented. Slip factors of impellers obtained experimentally and theoretically are compared. Losses in both vaneless diffuser and return channel with de-swirl vanes are discussed. Rotating stall was also investigated. Criteria for stall limit were tested.

scholarly journals Design and Performance Evaluation of a Very Low Flow Coefficient Centrifugal Compressor

2013 ◽  
Vol 2013 ◽  
pp. 1-12 ◽  
Author(s):  
Yongsheng Wang ◽  
Feng Lin ◽  
Chaoqun Nie ◽  
Abraham Engeda
Keyword(s):  
Centrifugal Compressor ◽  
Cfd Simulation ◽  
Volume Flow Rate ◽  
Three Dimensional ◽  
Flow Coefficient ◽  
Low Flow ◽  
Centrifugal Compressors ◽  
Lower Efficiency ◽  
One Dimensional ◽  
Low Flow Coefficient

Very low flow coefficient centrifugal compressors are often applied as the last stages of multistage compressors. Due to the lower volume flow rate, the flow channels in the impeller and diffuser are so narrow that friction loss becomes the main factor, which leads to lower efficiency than that of other stages in the same compressors. In addition, most of design methods are generally based on medium flow coefficient centrifugal compressors. Taking on researches on the low flow coefficient centrifugal compressors is significant and necessary. One-dimensional (1D) code, consisting of design and analysis parts, is developed in this study to provide basic geometric data and predict the entire performance of centrifugal compressor. Three-dimensional geometry of the impeller is built. CFD simulation is carried out as well to be compared with 1D prediction. With the continuous geometry adjustment, the final performance of the centrifugal compressor will be fixed once the performance discrepancy between CFD and one-dimensional code is acceptable. The details on the flow field within impeller will be presented through CFD.

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.

Development and Performance of the Wedge-Type Low Specific Speed Compressor Wheel

1982 ◽  
Author(s):  
V. Rusak
Keyword(s):  
Cross Sections ◽  
Development Program ◽  
Low Flow ◽  
Compressor Wheel ◽  
Good Efficiency ◽  
Friction Disk ◽  
Low Specific Speed ◽  
Specific Speed ◽  
Low Performance ◽  
And Performance

Low flow, low specific speed compressor stages are known to have inherently low performance level. Their low performance is attributed to a number of factors such as: high internal friction, disk friction, and leakage losses per unit mass flow. Comparative studies of design and performance indicated that it was possible to improve performance of the low specific speed compressor stages through the use of more favorable flow passage cross sections in the impellers. Use of wedge-shaped blades makes it possible to form such impeller flow passages. A major development program, started in early 1960’s, led to the emergency of the wedge-type compressor wheel as the wheel for low flow, low specific speed applications. The wheel is capable of operating in flow ranges previously designated for reciprocating compressors with an excellent operating range and good efficiency.

Effects of short blades on performance and inner flow characteristics of a low-specific-speed centrifugal pump

2017 ◽  
Vol 231 (4) ◽  
pp. 290-302 ◽  
Author(s):  
Can Kang ◽  
Ning Mao ◽  
Chen Pan ◽  
Yang Zhu ◽  
Bing Li
Keyword(s):  
Centrifugal Pump ◽  
Flow Rate ◽  
Pressure Fluctuations ◽  
Flow Characteristics ◽  
Low Flow ◽  
Back Surface ◽  
Flow Rates ◽  
Pump Operation ◽  
Low Specific Speed ◽  
Specific Speed

A low-specific-speed centrifugal pump equipped with long and short blades is studied. Emphasis is placed on the pump performance and inner flow characteristics at low flow rates. Each short blade is intentionally shifted towards the back surface of the neighboring long blade, and the outlet parts of the short blades are uniformly shortened. Unsteady numerical simulation is conducted to disclose inner flow patterns associated with the modified design. Thereby, a comparison is enabled between the two schemes featured by different short blades. Both practical operation data and numerical results support that the deviation and cutting of the short blades can eliminate the positive slope of pump head curve at low flow rates. Therefore, the modification of short blades improves the pump operation stability. Due to the shortening of the outlet parts of the short blades, velocity distributions between impeller outlet and radial diffuser inlet exhibit explicitly altered circumferential flow periodicity. Pressure fluctuations in the radial diffuser are complex in terms of diversified periodicity and amplitudes. Flow rate influences pressure fluctuations in the radial diffuser considerably. As flow rate decreases, the regularity of the orbit of hydraulic loads exerted upon the impeller collapses while hydraulic loads exerted upon the short blades remain circumferentially periodic.

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 Experimental Investigation of the Steady and Unsteady Relative Flow in a Model Centrifugal Impeller Passage

1993 ◽  
Author(s):  
M. Abramian ◽  
J. H. G. Howard
Keyword(s):  
Laser Doppler Anemometry ◽  
Quantitative Description ◽  
Rotating Stall ◽  
Secondary Flows ◽  
Operating Conditions ◽  
Low Flow ◽  
Centrifugal Impeller ◽  
Low Specific Speed ◽  
Specific Speed ◽  
Relative Flow

The behaviour of the relative flow in centrifugal turbomachines is extremely complex due to the existence of various fluid dynamic phenomena and their interaction. At design and off-design operating conditions, the relative flow is subject to stationary unsteadiness which includes flow separation and wakes associated with passage pressure gradients, secondary flows, and boundary layer stability. It may also be subject to periodic unsteadiness such as is the rotating stall and cyclic flow phenomena induced by the casing. This paper describes detailed measurements of the relative velocity field in a very low specific speed centrifugal pump impeller (Ns=515). Measurements were conducted by means of a recently developed rotating laser-Doppler anemometry system. Detailed quantitative description of the mean and fluctuating components of the primary and secondary velocity fields are presented for an impeller without volute at design, 50% design and shut-off conditions. The flow pattern in this low specific speed impeller with high blade loading is dominated by the relative eddy (a phenomenon also present in potential flow) which has suppressed suction side separation. When the impeller was fitted with a volute, the cyclic variation of the impeller exit flow, induced by the volute at low flow rates, is also presented.

scholarly journals Numerical characteristics of a centrifugal compressor with a low flow coefficient

2019 ◽  
Vol 140 ◽  
pp. 06010 ◽  
Author(s):  
Aleksey Yablokov ◽  
Ivan Yanin ◽  
Nikolay Sadovskyi ◽  
Yuri Kozhukhov ◽  
Minh Hai Nguyen
Keyword(s):  
Centrifugal Compressor ◽  
Numerical Study ◽  
Flow Coefficient ◽  
Ultrahigh Pressure ◽  
Low Flow ◽  
Classical Type ◽  
Numerical Characteristic ◽  
Wall Cell ◽  
Low Flow Coefficient ◽  
Near Wall

The study presents the simulation results of the viscid gas flow in low flow coefficient centrifugal compressor stages. The problem is solved in a stationary formulation using the Ansys CFX software package. The numerical simulation is carried out on three ultrahigh-pressure model stages; two stages have blades of the classical type impeller and one stage is of the bodily type. The value of the conditional flow coefficient is 0.0063 to 0.015. As part of the study, block-structured design meshes are used for all gas channel elements, with their total number being equaled as 13–15 million. During the calculations a numerical characteristic was validated with the results of tests carried out at the Department of Compressor, Vacuum and Refrigeration Engineering of Peter the Great St. Petersburg Polytechnic University. With an increase of inlet pressure as a result of a numerical study, it was found that for a given mathematical model the disk friction and leakage coefficient (1 + βfr + βlk) is overestimated. The analysis of flow in labyrinth seals has shown an increase of total temperature near the discs by 30–50 °С, nevertheless this fact did not influence gas parameters in the behind-the-rotor section. The calculation data obtained with finer design mesh (the first near-wall cell was 0.001 mm) is identical to those obtained with the first near-wall cell 0.01 mm mesh.

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