Three-Dimensional/One-Dimensional Combined Simulation of Deep Surge Loop in a Turbocharger Compressor With Vaned Diffuser

2019 ◽  
Vol 141 (7) ◽  
Author(s):  
Ghislaine Ngo Boum ◽  
Rodolfo Bontempo ◽  
Isabelle Trébinjac
Keyword(s):  
System Modeling ◽  
Air Flow ◽  
Three Dimensional ◽  
Navier Stokes ◽  
Vaned Diffuser ◽  
One Dimensional ◽  
Compressor Surge ◽  
Important Challenge ◽  
Unsteady Rans ◽  
Combined Simulation

High accuracy simulation of compressor surge origin and growth is an important challenge for designers of systems using compressors likely to develop that severe instability. Indeed, understanding its driving phenomena, which can be system dependent, is necessary to build an adequate strategy to avoid or control surge emergence. Computational fluid dynamics (CFD) simulations, commonly used to explore flow in the compressor, need then to be extended beyond the compressor as surge is a system scale instability. To get an insight on the path to surge and through surge cycles, a reliable alternative to full three-dimensional (3D) system modeling is used for a turbocharger compressor inserted in an experimental test rig. The air flow in the whole circuit, is modeled with a one-dimensional (1D) Navier Stokes approach which is coupled with a 3D unsteady RANS modeling of the 360 deg air flow in the centrifugal compressor including the volute. Starting from an initial stable flow solution in the system, the back-pressure valve is progressively closed to reduce the massflow and trigger the instability. An entire deep surge loop is simulated and compared with good agreement with the experimental data. The existence of a system-induced convective wave is revealed, and its major role on surge inception at diffuser inlet demonstrated.

Mechanism and Flow Control on the Mismatching of Impeller and Vaned Diffuser Caused by Inlet Prewhirl for Centrifugal Compressors

2016 ◽  
Author(s):  
Qiangqiang Huang ◽  
Xinqian Zheng ◽  
Aolin Wang
Keyword(s):  
Flow Control ◽  
Control Method ◽  
Three Dimensional ◽  
Navier Stokes ◽  
Vaned Diffuser ◽  
Inlet Distortion ◽  
Computational Fluid Dynamics Cfd ◽  
Stagger Angle ◽  
Good Agreement ◽  
Matching Relation

Air often flows into compressors with inlet prewhirl, because it will obtain a circumferential component of velocity via inlet distortion or swirl generators such as inlet guide vanes. A lot of research has shown that inlet prewhirl does influence the characteristics of components, but the change of the matching relation between the components caused by inlet prewhirl is still unclear. This paper investigates the influence of inlet prewhirl on the matching of the impeller and the diffuser and proposes a flow control method to cure mismatching. The approach combines steady three-dimensional Reynolds-averaged Navier-Stokes (RANS) simulations with theoretical analysis and modeling. The result shows that a compressor whose impeller and diffuser match well at zero prewhirl will go to mismatching at non-zero prewhirl. The diffuser throat gets too large to match the impeller at positive prewhirl and gets too small for matching at negative prewhirl. The choking mass flow of the impeller is more sensitive to inlet prewhirl than that of the diffuser, which is the main reason for the mismatching. To cure the mismatching via adjusting the diffuser vanes stagger angle, a one-dimensional method based on incidence matching has been proposed to yield a control schedule for adjusting the diffuser. The optimal stagger angle predicted by analytical method has good agreement with that predicted by computational fluid dynamics (CFD). The compressor is able to operate efficiently in a much broader flow range with the control schedule. The flow range, where the efficiency is above 80%, of the datum compressor and the compressor only employing inlet prewhirl and no control are just 25.3% and 31.8%, respectively. For the compressor following the control schedule, the flow range is improved up to 46.5%. This paper also provides the perspective of components matching to think about inlet distortion.

A Simulation of the Unsteady Interaction of a Centrifugal Impeller With its Vaned Diffuser: Flows Analysis

1994 ◽  
Author(s):  
W. N. Dawes
Keyword(s):  
Flow Analysis ◽  
Three Dimensional ◽  
Navier Stokes ◽  
Centrifugal Impeller ◽  
Vaned Diffuser ◽  
Time Resolved ◽  
High Loss ◽  
Swirl Angle ◽  
Unsteady Interaction ◽  
Unsteady Effects

The aim of this paper is to help advance our understanding of the complex, three-dimensional, unsteady flow associated with the interaction of a splattered centrifugal impeller and its vaned diffuser. A time-resolved simulation is presented of the Krain stage performed using a time-accurate, 3D, unstructured mesh, solution-adaptive Navier-Stokes solver. The predicted flowfield, compared with experiment where available, displays a complex, unsteady interaction especially in the neighbourhood of the diffuser entry zone which experiences large periodic flow unsteadiness. Downstream of the throat, although the magnitude of this unsteadiness diminishes rapidly, the flow has a highly distorted three-dimensional character. The loss levels in the diffuser are then investigated to try and determine how time-mean loss levels compare with the levels expected from “equivalent” steady flow analysis performed by using the circumferentially averaged exit flow from the impeller as inlet to the diffuser. It is concluded that little loss could be attributed directly to unsteady effects but rather that the principle cause of the rather high loss levels observed in the diffuser is the strong spanwise distortion in swirl angle at inlet which initiates a strong hub/comer stall.

scholarly journals Performance Investigation of a Turbocharger Compressor

2012 ◽  
Author(s):  
A. L. de Wet ◽  
T. W. von Backström ◽  
S. J. van der Spuy
Keyword(s):  
Pressure Ratio ◽  
Three Dimensional ◽  
Rotating Stall ◽  
Test Case ◽  
Test Cases ◽  
Vaned Diffuser ◽  
One Dimensional ◽  
Verification Process ◽  
The One ◽  
Modelling Methods

The compressor section of a diesel locomotive turbocharger was re-designed to increase its maximum total-to-total pressure ratio and efficiency. Tests conducted on the prototype compressor showed possible rotating stall in the diffuser section before the designed higher pressure ratio could be achieved. It was decided to simulate the prototype compressor’s operation by using one-dimensional theory [1], followed by a three-dimensional CFD analysis of the compressor. This publication focuses on implementation of the impeller, vaneless annular passage and vaned diffuser one-dimensional theories. A verification process was followed to show the accuracy of the one- and three-dimensional modelling methods using two well-known centrifugal compressor test cases found in the literature [2–5]. Comparing the test case modelling results to available experimental results indicated sufficient accuracy to investigate the prototype compressor’s impeller and diffuser. Conclusions drawn on the prototype compressor’s performance using the one- and three-dimensional modelling methods led to a recommendation to redesign the impeller and diffuser of the prototype compressor.

Aerodynamic Simulation of the Air Flow beneath the High Speed Train

2012 ◽  
Vol 253-255 ◽  
pp. 2035-2040
Author(s):  
Ye Bo Liu ◽  
Zhi Ming Liu
Keyword(s):  
High Speed ◽  
Stokes Equations ◽  
Air Flow ◽  
Pressure Coefficient ◽  
Three Dimensional ◽  
Navier Stokes ◽  
High Speed Train ◽  
Navier Stokes Equations ◽  
Pressure Distributions ◽  
High Speed Trains

Numerical simulations were carried out to investigate the air flow and pressure distributions beneath high speed trains, based on the three-dimensional Reynolds-averaged Navier-Stokes equations with the SST k-ω two-equation turbulence model. The simulation scenarios were of the high speed train, the CRH2, running in the open air at four different speeds: 200km/h, 250km/h, 300km/h and 350km/h. The results show that, the highest area of pressure is located at the front underbody part of the train whist the pressure for rest of the train is relatively small. Increasing speed does not visibly increase the pressure coefficient, indicating that the pressure increases with the square of the operational speed.

The Design of a Radial Turbine for Microgasturbine Applications

2003 ◽  
Author(s):  
Carlo Cravero ◽  
Martino Marini ◽  
Antonio Satta
Keyword(s):  
Critical Analysis ◽  
Three Dimensional ◽  
Design Tool ◽  
Navier Stokes ◽  
Complementary Information ◽  
One Dimensional ◽  
Radial Turbine ◽  
Automatic Software ◽  
Radial Inflow Turbine

An automatic software procedure, previously developed by the authors, is used for the design of a radial inflow turbine for microgasturbine applications. The procedure is formed by algorithms of different complexity levels ranging from the meanline one-dimensional design tool to the fully three-dimensional Navier-Stokes based analysis. Each code gives complementary information to the designer. The codes have been written and developed by the authors at DIMSET. The present application demonstrate the use of the above procedure and allows for a critical analysis of the tools involved.

Investigation of Periodically Unsteady Flow in a Radial Pump by CFD Simulations and LDV Measurements

2010 ◽  
Vol 133 (1) ◽  
Author(s):  
Jianjun Feng ◽  
Friedrich-Karl Benra ◽  
Hans Josef Dohmen
Keyword(s):  
Unsteady Flow ◽  
Stokes Equations ◽  
Three Dimensional ◽  
Measurement Data ◽  
Load Condition ◽  
Navier Stokes ◽  
Complex Flow ◽  
Data Set ◽  
Vaned Diffuser ◽  
Radial Pump

The periodically unsteady flow fields in a low specific speed radial diffuser pump have been investigated both numerically and experimentally for the design condition (Qdes) and also one part-load condition (0.5Qdes). Three-dimensional, unsteady Reynolds-averaged Navier–Stokes equations are solved on high-quality structured grids with the shear stress transport turbulence model by using the CFD (computational fluid dynamics) code CFX-10. Furthermore, two-dimensional laser Doppler velocimetry (LDV) measurements are successfully conducted in the interaction region between the impeller and the vaned diffuser, in order to capture the complex flow with abundant measurement data and to validate the CFD results. The analysis of the obtained results has been focused on the behavior of the periodic velocity field and the turbulence field, as well as the associated unsteady phenomena due to the unsteady interaction. In addition, the comparison between CFD and LDV results has also been addressed. The blade orientation effects caused by the impeller rotation are quantitatively examined and detailedly compared with the turbulence effect. This work offers a good data set to develop the comprehension of the impeller-diffuser interaction and how the flow varies with relative impeller position to the diffuser in radial diffuser pumps.

Numerical investigation into the effects of a radial gap on hydraulic turbine performance

2001 ◽  
Vol 215 (1) ◽  
pp. 99-107
Author(s):  
K Sato ◽  
L He
Keyword(s):  
Three Dimensional ◽  
Hydraulic Turbine ◽  
Turbine Rotor ◽  
Navier Stokes ◽  
Vaned Diffuser ◽  
Dual Time Stepping ◽  
The Difference ◽  
Nozzle Guide ◽  
Radial Gap ◽  
Nozzle Guide Vanes

The effects of the rotor/stator blade row interaction on the performance of radial turbine stages are investigated numerically. A three-dimensional unsteady incompressible Navier-Stokes method based on the dual-time stepping and the pseudocompressibility method is developed for the performance prediction. A centrifugal pump with a vaned diffuser is calculated for validation purposes, and the predicted unsteady flow results show reasonable agreement with the experimental data. The method is applied to analysis of hydraulic turbine stages. A generic turbine rotor is combined with a row of nozzle guide vanes with three settings of radial gap and numerical flow simulations are conducted for the performance evaluations. The predicted efficiency of the hydraulic turbine stages deteriorates if the radial gap between blade rows is reduced although the difference is very small. The entropy rises along the streamlines suggest that the differences in the stage efficiency level can be largely attributed to the loss generated in the nozzle vane passages.

Numerical Analysis of the Vaned Diffuser of a Transonic Centrifugal Compressor

2010 ◽  
Vol 132 (4) ◽  
Author(s):  
Michele Marconcini ◽  
Filippo Rubechini ◽  
Andrea Arnone ◽  
Seiichi Ibaraki
Keyword(s):  
Flow Field ◽  
Centrifugal Compressor ◽  
Pressure Ratio ◽  
Three Dimensional ◽  
Navier Stokes ◽  
Flow Measurements ◽  
Vaned Diffuser ◽  
High Pressure Ratio ◽  
Unsteady Interaction ◽  
Inlet Conditions

A three-dimensional Navier–Stokes solver is used to investigate the flow field of a high pressure ratio centrifugal compressor for turbocharger applications. Such a compressor consists of a double-splitter impeller followed by a vaned diffuser. Particular attention is focused on the analysis of the vaned diffuser, designed for high subsonic inlet conditions. The diffuser is characterized by a complex three-dimensional flow field and influenced by the unsteady interaction with the impeller. Detailed particle image velocimetry flow measurements within the diffuser are available for comparison purposes.

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