Application of Viscous Flow Computations for the Aerodynamic Performance of a Backswept Impeller at Various Operating Conditions

1988 ◽  
Vol 110 (3) ◽  
pp. 303-311 ◽  
Author(s):  
C. Hah ◽  
A. C. Bryans ◽  
Z. Moussa ◽  
M. E. Tomsho
Keyword(s):  
Experimental Data ◽  
Viscous Flow ◽  
Three Dimensional ◽  
Aerodynamic Performance ◽  
Operating Conditions ◽  
Centrifugal Impeller ◽  
Flow Phenomena ◽  
Overall Performance ◽  
Real Flow ◽  
Operating Points

Three-dimensional flowfields in a centrifugal impeller with backswept discharge at various operating points have been numerically investigated with a three-dimensional viscous flow code. Numerical results and experimental data were compared for the detailed flowfields and overall performance of the impeller at three operating conditions (optimum efficiency, choke, and near-surge conditions). The comparisons indicate that for engineering applications the numerical solution accurately predicts various complex real flow phenomena. The overall aerodynamic performance of the impeller is also well predicted at design and off-design conditions.

Numerical Investigation of the Aerodynamic Performance of Hybrid Aerofoils in a 1.5-Stage Low-Speed Compressor

2021 ◽  
Author(s):  
Jannik Eckel ◽  
Volker Gümmer
Keyword(s):  
Secondary Flow ◽  
Numerical Investigation ◽  
Three Dimensional ◽  
Aerodynamic Performance ◽  
Operating Conditions ◽  
Tip Vortex ◽  
Limiting Factors ◽  
Stall Inception ◽  
Low Speed ◽  
Flow Phenomena

Abstract This paper describes the numerical investigation of hybrid aerofoils in a 1.5-stage low-speed compressor, which in its baseline configuration features a conventional rotor and a tandem stator. Both of these are eventually replaced by hybrid aerofoils, using the initial tandem blade profile geometry around mid-span. In this course of design investigations a pure tandem rotor was also generated and analysed as the initial geometry of the hybrid rotor. The aerodynamic design and performance of the tandem rotor and the hybrid aerofoils will be discussed in this paper. The numerical analysis is aimed at understanding the secondary flow phenomena and limiting factors of the working range of the reference stage. Based on this knowledge, the advantages of the hybrid aerofoil design will be discussed. On one hand, the origin and development of three-dimensional flow structures near the endwall regions of the rear vane of the tandem stator are investigated in detail, as they appear to play a major role at de-throttled operating conditions. On the other hand, the tip vortex leakage of the single rotor and the pure tandem rotor are considered, showing the tip vortex taking a major role in loss generation and stall inception at throttled operating conditions, and interacting with the tandem stator secondary flow phenomena at the casing. Both these performance-limiting factors can be addressed by implementing hybrid aerofoils. The paper presents and discusses the improvement of secondary flow loses and aerodynamic performance based on steady-state RANS simulations.

Performance Characterization of a Twin Scroll Volute for Turbocharging Applications

2018 ◽  
Author(s):  
Carlo Cravero ◽  
Mario La Rocca ◽  
Andrea Ottonello
Keyword(s):  
Experimental Data ◽  
Scientific Literature ◽  
Aerodynamic Performance ◽  
Operating Conditions ◽  
Automatic Design ◽  
Cfd Model ◽  
Radial Turbine ◽  
Wide Range ◽  
Partial Admission

The use of twin scroll volutes in radial turbine for turbocharging applications has several advantages over single passage volute related to the engine matching and to the overall compactness. Twin scroll volutes are of increasing interest in power unit development but the open scientific literature on their performance and modelling is still quite limited. In the present work the performance of a twin scroll volute for a turbocharger radial turbine are investigated in some detail in a wide range of operating conditions at both full and partial admission. A CFD model for the volute have been developed and preliminary validated against experimental data available for the radial turbine. Then the numerical model has been used to generate the database of solutions that have been investigated and used to extract the performance. Different parameters and indices are introduced to describe the volute aerodynamic performance in the wide range of operating conditions chosen. The above parameters can be used for volute development or matching with a given rotor or efficiently implemented in automatic design optimization strategies.

scholarly journals The Design and Evaluation of a 14 Stage, 16:1 Pressure Ratio Compressor for an Industrial Gas Turbine

1996 ◽  
Author(s):  
Mohammad R. Saadatmand
Keyword(s):  
Experimental Data ◽  
Gas Turbine ◽  
Rotor Blade ◽  
Pressure Ratio ◽  
Three Dimensional ◽  
Operating Conditions ◽  
Suction Surface ◽  
Design Intent ◽  
Flow Through ◽  
Industrial Gas Turbine

The aerodynamic design process leading to the production configuration of a 14 stage, 16:1 pressure ratio compressor for the Taurus 70 gas turbine is described. The performance of the compressor is measured and compared to the design intent. Overall compressor performance at the design condition was found to be close to design intent. Flow profiles measured by vane mounted instrumentation are presented and discussed. The flow through the first rotor blade has been modeled at different operating conditions using the Dawes (1987) three-dimensional viscous code and the results are compared to the experimental data. The CFD prediction agreed well with the experimental data across the blade span, including the pile up of the boundary layer on the corner of the hub and the suction surface. The rotor blade was also analyzed with different grid refinement and the results were compared with the test data.

Calculations of Three-Dimensional, Viscous Flow and Wake Development in a Centrifugal Impeller

1981 ◽  
Vol 103 (2) ◽  
pp. 367-372 ◽  
Author(s):  
J. Moore ◽  
J. G. Moore
Keyword(s):  
Viscous Flow ◽  
Pressure Field ◽  
Three Dimensional ◽  
Inviscid Flow ◽  
Calculation Procedure ◽  
Wake Flow ◽  
Centrifugal Impeller ◽  
Duct Flow ◽  
Reduced Pressure ◽  
Flow Calculation

A partially-parabolic calculation procedure is used to calculate flow in a centrifugal impeller. This general-geometry, cascade-flow method is an extension of a duct-flow calculation procedure. The three-dimensional pressure field within the impeller is obtained by first performing a three-dimensional inviscid flow calculation and then adding a viscosity model and a viscous-wall boundary condition to allow calculation of the three-dimensional viscous flow. Wake flow, resulting from boundary layer accumulation in an adverse reduced-pressure gradient, causes blockage of the impeller passage and results in significant modifications of the pressure field. Calculated wake development and pressure distributions are compared with measurements.

Computational and Experimental Comparison of Different Volute Geometries in a Radial Compressor

2000 ◽  
Author(s):  
Arttu Reunanen ◽  
Harri Pitkänen ◽  
Timo Siikonen ◽  
Harri Heiska ◽  
Jaakko Larjola ◽  
...  
Keyword(s):  
Experimental Data ◽  
Time Dependent ◽  
Experimental Comparison ◽  
Cfd Analysis ◽  
Laboratory Measurements ◽  
Radial Compressor ◽  
Sliding Mesh ◽  
Overall Performance ◽  
Operating Points ◽  
Mesh Technique

Two different volute geometries of a radial compressor at three different operating points have been analyzed using Computational Fluid Dynamics and detailed laboratory measurements. The performance of the volutes were compared using steady-state CFD-analysis, where the volute and the impeller with diffuser were modeled separately. In addition, a time dependent simulation of the complete compressor using the sliding mesh technique was performed for one operation point. Both volutes were manufactured and the overall performance of the compressor, the pressure distribution in the volute and the flow field in the volute inlet were measured with the respective volute geometries. The results obtained from steady, quasi-steady and time-accurate simulations are compared with experimental data.

scholarly journals Numerical Investigation on Instability Flow Behaviors of Liquid Oxygen in a Feeding Pipeline with a Five-Way Spherical Cavity

Energies ◽  
2020 ◽  
Vol 13 (4) ◽  
pp. 926
Author(s):  
Fushou Xie ◽  
Siqi Xia ◽  
Erfeng Chen ◽  
Yanzhong Li ◽  
Hongwei Mao ◽  
...  
Keyword(s):  
Experimental Data ◽  
Spherical Cavity ◽  
Experimental Studies ◽  
Three Dimensional ◽  
Experimental System ◽  
Operating Conditions ◽  
Liquid Oxygen ◽  
Cavity Structure ◽  
Set Up ◽  
Pressure Fall

The hydrodynamic information of liquid oxygen in the conveying pipeline of cryogenic launch vehicles directly determines the reliability of the operation of the turbopump. A 0.09 MPa anomalous pressure fall phenomenon in the feeding system has been observed during the flight and run test of a cryogenic rocket with four parallel engines. In previous work, we set up a full-scale experimental system with liquid oxygen as media. The anomalous pressure fall was successfully reproduced. Experimental studies of this phenomenon suggest that the problem might be associated with vortices into the five-way spherical cavity structure. The objective of this study was to determine the three-dimensional instability flow by computational methods to identify and better understand the anomalous pressure fall phenomenon. A numerical model developed by the turbulent conservation equations was validated by experimental data. The generation and evolution of vortices into the five-way spherical cavity of feeding pipelines was captured. It was found that the root cause of the instability flow causing the unusual pressure fall is the formation of a spindle-like vortex into the five-way spherical cavity due to disturbance of the inlet liquid oxygen. The results showed that there is a mirror-symmetrical four-vortices structure in the absence of disturbance, in which the liquid oxygen pressure fall with the rise of the Reynolds number is in good agreement with the predicting values calculated by a set of traditional empirical correlations. In the case of the specific operating conditions, it is also consistent with the experimental results. When the disturbance occurs at the inlet of the spherical cavity, the mirror-symmetrical four-vortices structure gradually evolves into the mirror-symmetrical two-vortices structure. When the disturbance is further enhanced, the mirror-symmetrical two-vortices structure merge with each other to form a spindle-like vortex, which is similar to the Rankine vortex structure. The pressure fall on the corresponding side of the spindle-like vortex core reduces abnormally, and is about 0.07 MPa, which is consistent with the experimental data under certain disturbance conditions. Moreover, it was found that the spindle-like vortex is a stable eddy structure, and would continue to exist once it is formed, which could also not disappear with the removal of the disturbance.

Interaction of Labyrinth Seal Leakage Flow and Main Flow in an Axial Turbine

2003 ◽  
Author(s):  
A. Giboni ◽  
J. R. Menter ◽  
P. Peters ◽  
K. Wolter ◽  
H. Pfost ◽  
...  
Keyword(s):  
Secondary Flow ◽  
Three Dimensional ◽  
Labyrinth Seal ◽  
Main Flow ◽  
Experimental Program ◽  
Leakage Flow ◽  
Axial Turbine ◽  
Measurement Plane ◽  
Flow Phenomena ◽  
Operating Points

This paper presents the results of an experimental investigation into the flow in a 1.5-stage low-speed axial turbine with a straight labyrinth seal on the rotor shroud. The paper focuses on the interaction between the leakage flow and the main flow. The experimental program consists of measurements of the three-dimensional properties of the main flow downstream of the rotor trailing edge after the re-injection of the leakage flow. The measurements were carried out using pneumatic five-hole probes and three dimensional hot-wire probes at different operating points of the turbine. The measurement plane behind the rotor extends over one pitch from the shroud to the casing, with the complex three-dimensional flow field being mapped in great detail by 1,008 measurement points. As demonstrated in this paper, the entering leakage flow not only introduces mixing losses but also predominates the secondary flow behind the rotor and the second stator. The experimental data show that even at realistic clearance heights the leakage flow gives rise to negative incidence of considerable parts of the downstream stator which causes the flow to separate. Thus, labyrinth seal leakage flow should be taken properly into account in the design or optimisation process of turbomachinery. The high number of measurement points allows detailed analysis of the secondary flow phenomena and of the vortex structures. The time-dependence of the position and the intensity of the vortices is shown and the influence of the turbine’s operating point is presented.

scholarly journals Effects of Operating Conditions on the Flow in the Moving Blade Passage of a Single Stage Axial-Flow Fan

1997 ◽  
Vol 3 (4) ◽  
pp. 269-276 ◽  
Author(s):  
Tsutomu Adachi ◽  
Yutaka Yamashita ◽  
Kennichiro Yasuhara ◽  
Tatsuo Kawai
Keyword(s):  
Three Dimensional ◽  
Axial Flow ◽  
Operating Conditions ◽  
Tip Clearance ◽  
Hot Wire ◽  
Axial Flow Fan ◽  
Blade Passage ◽  
Operational Conditions ◽  
Flow Phenomena ◽  
Steady Velocity

Three dimensional steady and unsteady velocity distributions in the axial flow fan were measured using a hot wire probe for various operational conditions, various rotational speeds and various measuring positions. For measuring the velocity distributions in the blade passage, a specially designed and manufactured hot wire traversing apparatus was used. Steady velocity distributions, turning angles, effects of incident to the cascade, flow leakage through the tip clearance and effects of the flow separation show the flow phenomena through the blade passages. Unsteady velocity distributions show time dependent procedures of the wake flowing through the moving blade passage. Considering these results of measurements, the effects of the upstream stationary blade and the effects of Reynolds number on the flow were considered.

Flow in the Simplified Draft Tube of a Francis Turbine Operating at Partial Load—Part I: Simulation of the Vortex Rope

2014 ◽  
Vol 81 (6) ◽  
Author(s):  
Hosein Foroutan ◽  
Savas Yavuzkurt
Keyword(s):  
Experimental Data ◽  
Axial Velocity ◽  
Draft Tube ◽  
Three Dimensional ◽  
Operating Conditions ◽  
Turbulence Closure ◽  
Francis Turbine ◽  
Outer Flow ◽  
Vortex Rope ◽  
Partial Load

Numerical simulations and analysis of the vortex rope formation in a simplified draft tube of a model Francis turbine are carried out in this paper, which is the first part of a two-paper series. The emphasis of this part is on the simulation and investigation of flow using different turbulence closure models. Two part-load operating conditions with same head and different flow rates (91% and 70% of the best efficiency point (BEP) flow rate) are considered. Steady and unsteady simulations are carried out for axisymmetric and three-dimensional grid in a simplified axisymmetric geometry, and results are compared with experimental data. It is seen that steady simulations with Reynolds-averaged Navier–Stokes (RANS) models cannot resolve the vortex rope and give identical symmetric results for both the axisymmetric and three-dimensional flow geometries. These RANS simulations underpredict the axial velocity (by at least 14%) and turbulent kinetic energy (by at least 40%) near the center of the draft tube, even quite close to the design condition. Moving farther from the design point, models fail in predicting the correct levels of the axial velocity in the draft tube. Unsteady simulations are performed using unsteady RANS (URANS) and detached eddy simulation (DES) turbulence closure approaches. URANS models cannot capture the self-induced unsteadiness of the vortex rope and give steady solutions while DES model gives sufficient unsteady results. Using the proper unsteady model, i.e., DES, the overall shape of the vortex rope is correctly predicted and the calculated vortex rope frequency differs only 6% from experimental data. It is confirmed that the vortex rope is formed due to the roll-up of the shear layer at the interface between the low-velocity inner region created by the wake of the crown cone and highly swirling outer flow.

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