Numerical and Experimental Study of Impeller Diffuser Interaction

2002 ◽  
Author(s):  
Tarek Mekhail ◽  
Zhaohui Du ◽  
Willem Jansen ◽  
Hanping Chen
Keyword(s):  
Internal Flow ◽  
Leading Edge ◽  
Initial Guess ◽  
Interaction Region ◽  
Centrifugal Fan ◽  
Performance Measurements ◽  
Complex Flow ◽  
Vaned Diffuser ◽  
Flow Phenomena ◽  
Low Efficiency

The unsteadiness of the flow at the leading edge of a vaned diffuser represents a source of low efficiency and instability in a centrifugal turbomachine. Furthermore, the internal flow of the impeller can be affected by asymmetric downstream conditions, which results in extra flow unsteadiness and instabilities. Numerical and experimental data are obtained. The simulation of impeller diffuser interaction is performed using CFX-Tascflow. A frozen rotor simulation is used for the steady calculation and a rotor-stator simulation is used for the unsteady calculation using the steady results as an initial guess. The unsteady simulation is done not only for one impeller and diffuser blades, but also for the whole impeller and diffuser blades using Unix workstation. For the experimental work, a transparent fan is design and tested at The Turbomachinery Laboratory of SJTU. The test rig consists of a centrifugal, shrouded impeller, diffuser and volute casing all made of plexiglass. A particle image velocimeter (PIV) is used to measure the 2-D instantaneous velocity in the interaction region between impeller, vaned. A series of performance measurements were carried out at different speeds. The first trial of measuring the instantaneous flow field in a part of the impeller and vaned diffuser together at different relative locations between them is presented in this work at different flow rates. Obtaining detailed measurements in the interaction region between the impeller and diffuser can help in understanding the complex flow phenomena and improving centrifugal fan and compressor performance. Finally, the comparison between the unsteady measurements and unsteady calculations showed that the Rotor/Stator Model can predict the basic characteristics of unsteady flow in centrifugal fan but still need improvement to satisfy the true transient simulation for unsteady impeller diffuser interaction.

Flowfield and Performance Measurements in a Vaned Radial Diffuser

1986 ◽  
Vol 108 (2) ◽  
pp. 141-147 ◽  
Author(s):  
J. C. Dutton ◽  
P. Piemsomboon ◽  
P. E. Jenkins
Keyword(s):  
Flow Characteristics ◽  
Leading Edge ◽  
Performance Measurements ◽  
Mean Flow ◽  
Vaned Diffuser ◽  
Flow Angle ◽  
Flow Phenomena ◽  
The Mean ◽  
And Performance ◽  
High Degree

The flow characteristics of a vaned diffuser typical of those currently used in centrifugal compressors have been determined experimentally by using a static diffuser test rig. The vortex test vehicle (VTV) portion of this rig was used to simulate the essential features of the flow leaving the impeller of an actual compressor. The mean flow phenomena at the diffuser entrance and the static pressure recovery along the diffuser passage have been determined. In addition, the flow angle and Mach number distributions at several key locations throughout the diffuser channel have been obtained. The most notable feature of the diffuser flowfield is the high degree of nonuniformity in the inlet/leading edge region.

A Study of Impeller-Diffuser-Volute Interaction in a Centrifugal Fan

2005 ◽  
Vol 127 (1) ◽  
pp. 84-90 ◽  
Author(s):  
Tarek Meakhail ◽  
Seung O. Park
Keyword(s):  
Simulation Model ◽  
Velocity Measurement ◽  
Measurement Data ◽  
Flow Simulation ◽  
Separated Flow ◽  
Quantitative Agreement ◽  
Initial Guess ◽  
Centrifugal Fan ◽  
Vaned Diffuser ◽  
Commercial Code

This paper reports velocity measurement data in the interaction region between the impeller and vaned diffuser and the results of numerical flow simulation of the whole machine (impeller, vaned diffuser and volute) of a single stage centrifugal fan. Two-dimensional instantaneous velocity measurement is done using particle image velocimetry (PIV). Numerical simulation of impeller-diffuser-volute interaction is performed using CFX-Tascflow commercial code. A frozen rotor simulation model is used for the steady calculation and a rotor-stator simulation model is used for the unsteady calculation using the steady results as an initial guess. The simulation results show that the separated flow regime near the diffuser hub extends to the volute. Comparison between the unsteady computation and those of measurement indicates that the rotor/stator model employed in the simulation predicts essential characteristics of unsteady flow in the centrifugal fan. However, quantitative agreement remains rather poor.

Experimental Study for the Effect of Vaned Diffuser Leading Edge on the Noise Generated From a Centrifugal Fan

2009 ◽  
Author(s):  
Wei Zhang ◽  
Wu Qi Gong ◽  
Xiao Hua Fan ◽  
Guang Xi
Keyword(s):  
Leading Edge ◽  
Flow Coefficient ◽  
Centrifugal Fan ◽  
Test Results ◽  
Fan Noise ◽  
Experimental Conditions ◽  
Vaned Diffuser ◽  
Flow Rate Coefficient ◽  
Aerodynamic Performances ◽  
Inclined Angle

This paper studies a novel vaned diffuser with inclined leading edge to reduce the fan noise. The aerodynamic performances and sound pressure level (SPL) of the centrifugal fan with five different diffusers were measured in an anechoic chamber, and the inclined angles of the five diffusers are 45°, 60°, 120°, 135° and 150°, respectively. The flow coefficient of the fan varies from 0.037 to 0.14, the rotational speed ranges from 20000rpm to 35000rpm. The test results show that, by using diffuser vanes with inclined leading edge, the overall noise of the fan is reduced in the experimental conditions, and it has the minimum value at the flow rate coefficient of 0.084. The overall noise reduction of 5.3dB was made with the diffuser leading edge inclined angle of 150°.

Numerical Investigation of Diffuser Flow Field and Rotating Stall in a Centrifugal Compressor With Vaned Diffuser

2017 ◽  
Author(s):  
Yang Zhao ◽  
Jiayi Zhao ◽  
Zhiheng Wang ◽  
Guang Xi
Keyword(s):  
Centrifugal Compressor ◽  
Leading Edge ◽  
Suction Side ◽  
Rotating Stall ◽  
Tip Leakage Flow ◽  
Vaned Diffuser ◽  
Flow Angle ◽  
Diffuser Flow ◽  
Flow Phenomena ◽  
Reversal Flow

The diffuser rotating stall in a centrifugal compressor with vaned diffuser is one of important unsteady flow phenomena, which limits the operating range of the compressor. In this paper, the unsteady CFD analysis on a low-speed centrifugal compressor has been performed to investigate the flow characteristic in the diffuser and the propagation of the diffuser rotating stall. The flow behaviors at the outlet of the impeller at design and off-design conditions are firstly investigated. It is found that a reversal flow, induced by the tip leakage flow, exists near the shroud at the impeller outlet and becomes serious with the mass flow rate reduced. Due to the span-wise variation of the flow angle at the diffuser inlet and the inversed pressure gradient in the passage, the leading-edge vortex (LEV) generates on the diffuser leading edge. The LEV then induces the secondary flow in the diffuser passage and then causes the hub-corner separation. Furthermore, the propagation of the diffuser rotating stall is presented in details. The suction-side separation near the hub induces the blockage in the passage. And the shedding vortex from the suction side moves toward the leading edge of the adjacent blade. When the vortex reaches to the leading edge of the adjacent blade, the incidence increase and a new separation occurs on the suction side. With the development of the new separation, the passage becomes blocked gradually and the upstream stalled passage recovers to a normal condition. The rotating stall propagates along the direction of the impeller rotation at about 4.5% of the impeller rotational speed.

High Efficiency and Low Pressure Fluctuation Redesign of a Centrifugal Pump Based on Unsteady CFD Analyses

2015 ◽  
Author(s):  
Peng Yan ◽  
Peng Wu ◽  
Dazhuan Wu
Keyword(s):  
Centrifugal Pump ◽  
Pressure Fluctuation ◽  
High Efficiency ◽  
Stokes Equations ◽  
Internal Flow ◽  
Leading Edge ◽  
Radial Force ◽  
Navier Stokes ◽  
Low Efficiency ◽  
Cfd Analyses

In this study, a double volute centrifugal pump of relative low efficiency and high vibration was redesigned with the aid of unsteady CFD analyses. The local Euler head distribution (LEHD) representing the energy growth from the blade leading edge to trailing edge on s1 stream surface in a viscous flow field was introduced to evaluate the flow on s1 stream surfaces from hub to shroud. To investigate the unsteady internal flow of the centrifugal pump, the unsteady Reynolds-averaged Navier-Stokes equations (URANS) were solved with realizable k-ε turbulence model using the CFD code FLUENT. The impeller was redesigned with the same outlet diameter as prototype pump. A two-step-form LEHD was recommended to suppress flow separation and secondary flow encountered in the prototype impeller to improve the efficiency. The splitter was added to improve the hydraulic performance and reduce unsteady radial forces. The original double volute was substituted by a newly designed single volute. The hydraulic efficiency of the redesigned centrifugal pump is 89.2%, 3.2% higher than the prototype pump. The pressure fluctuation in volute is significantly reduced and the mean and max values of unsteady radial force are only 30% and 26.5% of the prototype pump.

Experimental and Numerical Investigation of the Flow Field in the Radial Inlet of a Centrifugal Compressor

2012 ◽  
Author(s):  
Fenghui Han ◽  
Datong Qi ◽  
Jiajian Tan ◽  
Li Wang ◽  
Yijun Mao
Keyword(s):  
Flow Field ◽  
Centrifugal Compressor ◽  
Numerical Study ◽  
Internal Flow ◽  
Structure Design ◽  
Outlet Section ◽  
Complex Flow ◽  
Flow Angle ◽  
Flow Phenomena ◽  
Probe Calibration

This paper presents an experimental and numerical study of the flow field in a typical geometry of a centrifugal compressor radial inlet. A five-hole probe system, which makes the probe calibration and the data acquisition automatically controlled by computer, was developed and used to measure the pressure, velocity and flow angle distributions inside the radial inlet. The testing portion consists of the entrance and exit of the radial inlet, the outlet section of the suction nozzle and the exit of the plenum, including 46 sampling holes and 923 measuring points. In parallel with the experiment, a computational analysis was also carried out to simulate the internal flow of the radial inlet with a commercial CFD Code. The numerical results are compared with the experimental data. It shows a good agreement between CFD and the measurement on most sections. Based on the experiment and simulation, this study reveals the detailed flow conditions in a radial inlet, which helps to figure out how the complex flow pattern in a radial inlet forms and develops as well as the influences on the downstream components. It yields an improved understanding of the principle of flow phenomena in radial inlets, and gives recommendations for optimizing the structure design of the radial inlet of centrifugal compressors.

Noise reduction mechanisms for the inclined leading edge vaned diffuser in a centrifugal fan

2017 ◽  
Vol 231 (1) ◽  
pp. 68-83 ◽  
Author(s):  
Gong Wu Qi ◽  
Zhang Wei
Keyword(s):  
Noise Reduction ◽  
Pressure Fluctuation ◽  
Numerical Study ◽  
Second Harmonic ◽  
Leading Edge ◽  
Centrifugal Fan ◽  
Fan Noise ◽  
Vaned Diffuser ◽  
Reduction Mechanisms ◽  
Centrifugal Fans

An experimental and numerical study to explore the noise reduction mechanism for the inclined leading edge vaned diffuser in centrifugal fans is described. Inclined leading edge vaned diffuser is useful in improving fan performance, increasing operating range, and reducing fan noise. The generation of fan noise is related to the pressure fluctuation on the diffuser vane surface, particularly the leading edge. Numerical results show that pressure fluctuation on the inclined leading edge vaned diffuser surface remarkably decreases, unlike that of the original diffuser. The pressure fluctuation is dominated by the components at the blade passing frequency and its second harmonic.

A Study of Impeller-Diffuser-Volute Interaction in a Centrifugal Fan

2004 ◽  
Author(s):  
Tarek Meakhail ◽  
Seung O. Park
Keyword(s):  
Simulation Model ◽  
Velocity Measurement ◽  
Measurement Data ◽  
Flow Simulation ◽  
Separated Flow ◽  
Quantitative Agreement ◽  
Initial Guess ◽  
Centrifugal Fan ◽  
Vaned Diffuser ◽  
Commercial Code

This paper reports velocity measurement data in the interaction region between the impeller and vaned diffuser and the results of numerical flow simulation of the whole machine (impeller, vaned diffuser and volute) of a single stage centrifugal fan. Two-Dimensional instantaneous velocity measurement is done using particle image velocimetry (PIV). Numerical simulation of impeller-diffuser-volute interaction is performed using CFX-Tascflow commercial code. A frozen rotor simulation model is used for the steady calculation and a rotor-stator simulation model is used for the unsteady calculation using the steady results as an initial guess. The simulation results show that the separated flow regime near the diffuser hub extends to the volute. Comparison between the unsteady computation and those of measurement indicates that the Rotor/Stator Model employed in the simulation predicts essential characteristics of unsteady flow in the centrifugal fan. However, quantitative agreement remains rather poor.

A Study on Centrifugal Impeller and Diffuser Flow

1981 ◽  
Vol 103 (4) ◽  
pp. 688-697 ◽  
Author(s):  
H. Krain
Keyword(s):  
Internal Flow ◽  
Leading Edge ◽  
Maximum Flow ◽  
Wake Flow ◽  
Optical Measurements ◽  
Centrifugal Impeller ◽  
Vaned Diffuser ◽  
Flow Angle ◽  
Field Development ◽  
Adjacent Channels

The flow field development within a centrifugal compressor stage was analyzed using an advanced laser velocimetry [4]. A splitter blade impeller coupled with a vaned and vaneless diffuser has been found to have similar internal flow patterns for both the vaneless and vaned diffuser design. Different velocity profiles have been analyzed for adjacent channels behind the splitter blade leading edge. A considerable wake flow was observed near the impeller exit. Detailed optical measurements within the vaned diffuser entrance region gave evidence of a periodically fluctuating, highly distorted diffuser inlet flow. Unsteady flow angle deviations of 13 degrees have been discovered within the diffuser throat. Maximum flow angle differences up to 27 degrees occurred from hub to shroud.

Design of High-Speed Magnetic Centrifugal Blower Impeller and Numerical Simulation of Internal Flow Field

2012 ◽  
Vol 150 ◽  
pp. 154-159
Author(s):  
Zhao Kui Wang ◽  
Shu Qin Liu ◽  
Hong Wei Li ◽  
Bin Bian
Keyword(s):  
Flow Field ◽  
High Speed ◽  
Magnetic Levitation ◽  
Flow Analysis ◽  
Calculated Data ◽  
Simple Algorithm ◽  
Internal Flow ◽  
Centrifugal Fan ◽  
Design Data ◽  
Low Efficiency

Currently, most domestic blower speed is still in 3000r/min level. The friction loss of mechanical bearings results in their low efficiency. To further improve the efficiency of the fan, a new high-speed maglev centrifugal fan was developed specially. The design of impeller styles, structure and size are rational. 3D graphics of the impeller and volute were drawn by using solidworks software. Application of CFD flow analysis software and the SIMPLE algorithm described viscous flow field within the three-dimensional centrifugal fan. By comparing simulation data with calculated data, optimize the turbine design. The simulative results are basically consistent with the design data, which provides a theoretical basis for the design of a new high-speed magnetic levitation fans, improving the level of centrifugal fan design.

Sign in / Sign up

Export Citation Format

Share Document