Combined Impeller-Diffuser Design and the Influence of Slotted Guide Vanes on the Performance of Radial Diffusers

2009 ◽  
Author(s):  
Philipp Epple ◽  
Mihai Miclea ◽  
Caslav Ilic ◽  
Antonio Delgado
Keyword(s):  
Flow Rate ◽  
Design Method ◽  
Maximum Flow ◽  
Vaneless Diffuser ◽  
Test Rig ◽  
Vaned Diffuser ◽  
Advantages And Disadvantages ◽  
Major Loss ◽  
Working Principle ◽  
The One

Radial diffusers are devices to increase the static pressure of a radial impeller-diffuser-unit (IDU) and in many cases also its efficiency. A new design method for the coupled Impeller-Diffuser-Layout is proposed. This new design method is presented and the resulting theoretical differences of the vaned and vaneless diffusers are shown. It is known, also, that at high flow rates, the vaned diffusers will choke, i.e. the maximum flow rate of an IDU will be much less as the one of the impeller alone or an IDU with vaneless diffuser. In order to avoid the flow rate decrease in the vaned diffuser due to this blockage or choking, a new kind of diffuser is proposed: the slotted diffuser. The theoretical principles of chocking and the solution with the slotted diffusers are explained. In order to have an in depth understanding of its working principle, three IDU are numerically examinated: with vaneless diffuser, regular vaned diffuser and the new slotted diffuser. In general the slotted diffuser delivers approximately the same pressure and efficiency but a substantial higher flow rate than the vaned diffuser. The vaneless diffuser has the highest flow rate, but the lowest pressure. An in detail analysis of the gap losses between the exit of the impeller and the entry of the vaned regular and slotted diffusers is presented, unrevealing an major loss source in vaned IDU. Flow patterns of the different diffuser types are shown illustrating in a clear manner the working principle of these diffusers and their respective advantages and disadvantages. Finally, in order to validate the theoretical and numerical results, prototypes were built and measurements performed at a norm test rig according to DIN 24 163. Pictures of the prototypes as well as of the test rig are shown. The experimental results are in good agreement with the predictions of the numerical simulations confirming the theoretical and numerical investigations.

The Application of PIV in the Study of Impeller-Diffuser Interaction in Centrifugal Fan: Part I — Impeller-Vaneless Diffuser Interaction

2001 ◽  
Author(s):  
Tarek Mekhail ◽  
Zhang Li ◽  
Du Zhaohui ◽  
Willem Jansen ◽  
Chen Hanping
Keyword(s):  
Flow Field ◽  
Flow Rate ◽  
High Speed ◽  
Maximum Flow ◽  
Image Processing Technique ◽  
High Speed Photography ◽  
Centrifugal Fan ◽  
Performance Measurements ◽  
Vaneless Diffuser ◽  
Unstable Flow

Abstract The PIV (Particle Image Velocimetry) technology is a brand-new technique of measuring velocity. It started in the 1980’s with the development of high-speed photography and the image processing technique of computers. This article deals with PIV applied to the study of unsteady impeller-vaneless diffuser interaction in centrifugal fen. Experiments were carried out at The Turbomachinery Laboratory of Shanghai Jiaotong University. The test rig consists of a centrifugal, shrouded impeller, diffuser and volute casing all made of plexiglass. A series of performance measurements were carried out at different speeds and different vaneless diffuser widths. PIV measurements were applied to measure the unsteady flow at the exit part of the impeller and the inlet part of the diffuser for the case of the same width vaneless diffuser. The absolute flow field is measured at medium flow rate and at maximum flow rate. It is informative to capture the whole flow field at the same instant of time, and it might be more revealing to observe the unstable flow in real time.

Off-Design Flow Measurements in a Centrifugal Compressor Vaneless Diffuser

1995 ◽  
Vol 117 (4) ◽  
pp. 602-608 ◽  
Author(s):  
A. Pinarbasi ◽  
M. W. Johnson
Keyword(s):  
Flow Rate ◽  
Centrifugal Compressor ◽  
Secondary Flows ◽  
Design Flow ◽  
Vaneless Diffuser ◽  
Flow Measurements ◽  
Vaned Diffuser ◽  
Flow Angle ◽  
Flow Rates ◽  
Study Results

Detailed measurements have been taken of the three-dimensional velocity field within the vaneless diffuser of a backswept low speed centrifugal compressor using hot-wire anemometry. A 16 percent below and an 11 percent above design flow rate were used in the present study. Results at both flow rates show how the blade wake mixes out more rapidly than the passage wake. Strong secondary flows inherited from the impeller at the higher flow rate delay the mixing out of the circumferential velocity variations, but at both flow rates these circumferential variations are negligible at the last measurement station. The measured tangential/radial flow angle is used to recommend optimum values for the vaneless space and vane angle for design of a vaned diffuser.

scholarly journals Study on Two Types of Stall Patterns in a Centrifugal Compressor with a Wide Vaneless Diffuser

Processes ◽  
2020 ◽  
Vol 8 (10) ◽  
pp. 1251
Author(s):  
Qian Zhang ◽  
Liang Zhang ◽  
Qiuhong Huo ◽  
Lei Zhang
Keyword(s):  
Flow Rate ◽  
Centrifugal Compressor ◽  
Three Dimensional ◽  
Propagation Speed ◽  
Radius Ratio ◽  
Vaneless Diffuser ◽  
Vaneless Diffusers ◽  
Stall Cells ◽  
The Stability ◽  
The One

Two types of stall patterns in the centrifugal compressor with a wide vaneless diffuser were numerically studied in this paper. We carried out kinds of three-dimensional numerical simulations of the instability process in wide vaneless diffusers with different radius ratios. The results show that there are two kinds of stall patterns in wide vaneless diffusers with different radius ratios. For a short diffuser with a radius ratio of 1.5, the speed of the propagation of stalled cells is relatively high, and the propagation speed and frequency of stall cells do not change with the decrease in the flow rate. For a long diffuser with a radius ratio of 1.8, the propagation velocity of stall cells is smaller to the one in the short diffuser, and increases with the decrease in flow rate. For wide vaneless diffusers with different radius ratios, the main factor causing stall is the outlet reflux. Reducing the radius ratio of the wide vaneless diffuser has an important influence on the stability of the centrifugal compressor.

scholarly journals Measurement of the Flow of the River Canastra in Itapuranga (Goiás) as a strategy for Planning and Management of Hydrographic Basins

2021 ◽  
Vol 17 (2) ◽  
Author(s):  
Josimar dos Reis de Souza ◽  
Edgar Campos Ferreira ◽  
Laís Naiara Gonçalves dos Reis
Keyword(s):  
Urban Area ◽  
Flow Rate ◽  
Maximum Flow ◽  
Water Source ◽  
Financial Resources ◽  
Agricultural Activities ◽  
Float Method ◽  
Planning And Management ◽  
Increasing Demand ◽  
The One

This study aimed to measure the flow of the Canastra River, located in the municipality of Itapuranga (Goiás), from 2017 to 2018, using the float method. This river plays an important role in providing water for the urban area, for industry and for the irrigation of extensive areas of cultivation. Thus, the analysis focused on showing how these results can contribute to the planning and management of river basins. The methodology used for data collection was the estimation by the float method. The results obtained showed that in the wettest months the flow rate reached a relative average of 200 m³/s, with a maximum flow rate of 450 m³/s. In the dry months, especially in October 2018, the flow reached a minimum of 4.1 m³/s. The flow data of the watercourse allowed to show the extremes of the water source capacity, which has been increasingly under pressure from increasing demand for supply in the urban area of Itapuranga and also from industries and agricultural activities. Furthermore, this experimental study demonstrated how the use of techniques considered simple and cheap, such as the one used, emerge as possibilities for the practice of watershed management, available to managers, especially in small municipalities in the country with limited financial resources.

A Study on Matching Between Centrifugal Compressor Impeller and Low Solidity Diffuser and its Extension to Vaneless Diffuser

2018 ◽  
Author(s):  
Hideaki Tamaki
Keyword(s):  
High Pressure ◽  
Flow Rate ◽  
Centrifugal Compressor ◽  
Maximum Flow ◽  
Maximum Flow Rate ◽  
Pressure Recovery ◽  
Low Flow ◽  
Vaneless Diffuser ◽  
Operating Range ◽  
Wide Operating

A centrifugal compressor requires a wide operating range as well as a high efficiency. At high pressure ratios, the impeller discharge velocity becomes transonic and effective pressure recovery in a vaned or vaneless diffuser is necessary. At high pressure ratios, a vaned diffuser is used as it has high pressure recovery, but may have a narrow operating range. At low flow, diffuser stall may trigger surge. At high flow, choking in the throat of the vanes may limit the maximum flow rate. A low solidity diffuser allows a good pressure recovery because it has vanes to guide the flow and a wide operating range as there is no geometrical throat to limit the maximum flow. In experimental studies at a pressure ratio around 4:1, the author has replaced vaned diffusers with a range of low solidity diffusers to try to broaden the operating range. The test results showed that the low solidity diffuser also chokes. In this paper, a virtual throat is defined and its existence is confirmed by flow visualization and pressure measurements. A method to select low solidity diffusers is proposed based on test data and the fundamental nature of the flow. The extension of the proposed method to the selection of a vaneless diffuser is examined and a design approach for a vaneless diffuser system to minimize surge flow rate without limiting the attainable maximum flow rate is proposed.

Impeller-Vaned Diffuser Interaction in a Centrifugal Compressor at Off Design Conditions

2012 ◽  
Vol 134 (6) ◽  
Author(s):  
P. Gaetani ◽  
G. Persico ◽  
A. Mora ◽  
V. Dossena ◽  
C. Osnaghi
Keyword(s):  
Flow Rate ◽  
Strong Dependence ◽  
Maximum Flow ◽  
Fast Response ◽  
Huge Number ◽  
Vaned Diffuser ◽  
Experimental Campaign ◽  
Flow Features ◽  
Aero Engines ◽  
Operating Points

As centrifugal compressors find a huge number of applications in industry and in aero-engines, the detailed analysis and comprehension of the impeller-vaned diffuser interaction is of interest to improve the efficiency and the operating range. This paper presents the results of a wide experimental campaign devoted to the understanding of the impeller-diffuser interaction; in particular, the paper focuses on the features occurring when the compressor works in off design conditions. Data were taken at three operating points (near surge, best efficiency, and maximum flow rate point) in the impeller-vaned diffuser gap by a fast response probe; the single stage compressor runs at 12,500 RPM giving a peripheral Mach number of 0.77. At first, data are reduced to evidence the main impeller flow features, which are compared at different flow rates. Furthermore time mean diffuser effects on the impeller are commented and finally the impeller-diffuser interaction is discussed. Results evidence the effect of the diffuser on the impeller, mainly in terms of static pressure and flow velocity, which have a strong dependence on the flow rate.

Impeller–Vaned Diffuser Interaction in a Centrifugal Compressor at Off Design Conditions

2011 ◽  
Author(s):  
P. Gaetani ◽  
G. Persico ◽  
A. Mora ◽  
V. Dossena ◽  
C. Osnaghi
Keyword(s):  
Flow Rate ◽  
Strong Dependence ◽  
Maximum Flow ◽  
Fast Response ◽  
Huge Number ◽  
Vaned Diffuser ◽  
Experimental Campaign ◽  
Aero Engine ◽  
Flow Features ◽  
Operating Points

As centrifugal compressors find a huge number of applications in industry and in aero-engine, the detailed analysis and comprehension of the impeller–vaned diffuser interaction is of interest to improve the efficiency and the operating range. The paper presents the results of a wide experimental campaign devoted to the understanding of the impeller–diffuser interaction; in particular the paper focuses on the features occurring when the compressor works in off design conditions. Data were taken at 3 operating points (near surge, best efficiency and maximum flow rate point) in the impeller–vaned diffuser gap by a fast response probe; the single stage compressor runs at 12500 RPM giving peripheral Mach number of 0.77. At first, data are reduced to evidence the main impeller flow features which are compared at different flow rates. Furthermore time mean diffuser effects on the impeller are commented and finally the impeller–diffuser interaction is discussed. Results evidence the effect of the diffuser on the impeller, mainly in terms of static pressure and flow velocity, which have a strong dependence on the flow rate.

A Study on Matching Between Centrifugal Compressor Impeller and Low Solidity Diffuser and Its Extension to Vaneless Diffuser

2018 ◽  
Vol 141 (4) ◽  
Author(s):  
Hideaki Tamaki
Keyword(s):  
High Pressure ◽  
Flow Rate ◽  
Centrifugal Compressor ◽  
Maximum Flow ◽  
Maximum Flow Rate ◽  
Pressure Recovery ◽  
Low Flow ◽  
Vaneless Diffuser ◽  
Operating Range ◽  
Wide Operating

A centrifugal compressor requires a wide operating range as well as a high efficiency. At high pressure ratios, the impeller discharge velocity becomes transonic and effective pressure recovery in a vaned or vaneless diffuser is necessary. At high pressure ratios, a vaned diffuser is used as it has high pressure recovery, but may have a narrow operating range. At low flow, diffuser stall may trigger surge. At high flow, choking in the throat of the vanes may limit the maximum flow rate. A low solidity diffuser allows a good pressure recovery because it has vanes to guide the flow and a wide operating range as there is no geometrical throat to limit the maximum flow. In experimental studies at a pressure ratio around 4:1, the author has replaced vaned diffusers with a range of low solidity diffusers to try to broaden the operating range. The test results showed that the low solidity diffuser also chokes. In this paper, a virtual throat is defined and its existence is confirmed by flow visualization and pressure measurements. A method to select low solidity diffusers is proposed based on test data and the fundamental nature of the flow. The extension of the proposed method to the selection of a vaneless diffuser is examined and a design approach for a vaneless diffuser system to minimize surge flow rate without limiting the attainable maximum flow rate is proposed.

Outcome of Buccal Mucosal Graft Urethroplasty in Long Segment Anterior Urethral Stricture

2020 ◽  
Vol 19 (2) ◽  
pp. 64-68
Author(s):  
Mrinmoy Biswas ◽  
Sudip Das Gupta ◽  
Mohammed Mizanur Rahman ◽  
Sharif Mohammad Wasimuddin
Keyword(s):  
Urethral Stricture ◽  
Flow Rate ◽  
Surgical Outcome ◽  
Simple Technique ◽  
Anterior Segment ◽  
Maximum Flow ◽  
Anastomotic Site ◽  
Buccal Mucosal Graft ◽  
Male Patients

Objective: To assess the success of BMG urethroplasty in long segment anterior urethral stricture. Method: From January 2014 to December 2015, twenty male patients with long anterior segment urethral stricture were managed by BMG urethroplasty. After voiding trial they were followed up at 3 month with Uroflowmetry, RGU & MCU and PVR measurement by USG. Patients were further followed up with Uroflowmetry and PVR at 6 months interval.Successful outcome was defined as normal voiding with a maximum flow rate >15ml /sec and PVR<50 ml with consideration of maximum one attempt of OIU after catheter removal. Results: Mean stricture length was 5.2 cm (range 3-9 cm) and mean follow-up was 15.55 months (range 6-23 months). Only two patients developed stricture at proximal anastomotic site during follow-up. One of them voided normally after single attempt of OIU. Other one required second attempt of OIU and was considered as failure (5%). Conclusion: BMG urethroplasty is a simple technique with good surgical outcome. Bangladesh Journal of Urology, Vol. 19, No. 2, July 2016 p.64-68

Hybrid polymer composite materials. Part 2. Preparation technology

2020 ◽  
pp. 8-13
Keyword(s):  
Composite Materials ◽  
Impact Toughness ◽  
Polymer Composites ◽  
The Other ◽  
Polymer Materials ◽  
Hybrid Polymer ◽  
Preparation Technology ◽  
Advantages And Disadvantages ◽  
Hybrid Polymer Composite ◽  
The One

The main methods (pressing and winding) of the processing of hybrid polymer composites to obtain items were examined. Advantages and disadvantages of the methods were noted. Good combinations of different-module fibers (carbon, glass, boron, organic) in hybrid polymer materials are described, which allow one to prepare materials with high compression strength on the one hand, and to increase fracture energy of samples and impact toughness on the other hand.

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