Analysis of Turbofan Performance Under Total Pressure Distortion at Various Operating Points

2015 ◽  
Author(s):  
David B. Weston ◽  
Steven E. Gorrell ◽  
Matthew L. Marshall ◽  
Carol V. Wallis
Keyword(s):  
Total Pressure ◽  
Operating Conditions ◽  
Rotor Blades ◽  
Cfd Simulations ◽  
Blade Loading ◽  
Distortion Analysis ◽  
Work Input ◽  
Total Temperature ◽  
Computational Fluid Dynamics Cfd ◽  
Operating Points

Inlet distortion is an important consideration in fan performance. The focus of this paper is a series of high-fidelity time accurate Computational Fluid Dynamics (CFD) simulations of a multistage fan at choke, design, and near stall operating conditions. These investigate distortion transfer and generation as well as the underlying flow physics of these phenomena under different operating conditions. The simulations are performed on the full annulus of a 3 stage fan and are analyzed. The code used to carry out these simulations is a modified version of OVERFLOW 2.2. The inlet is specified as a 1/rev total pressure distortion. Analysis includes the phase and amplitude of total temperature and pressure distortion through each stage of the fan and blade loading. The total pressure distortion does not change in severity through the fan, but the peak pressure distortion rotates by as much as 45° at the near stall point. This is due to a variation in the work input around the blades of the rotor. This variation is also responsible for the generation of total temperature distortion in the fan. The rotation of the total temperature distortion becomes more pronounced as the fan approaches stall, and the total temperature distortion levels increase. The amount of work performed by a single blade can vary by as much as 25% in the first stage at near stall. The variation in work becomes more pronounced as the fan approaches stall. The passage shock in the rotor blades moves nearly 20% of the blade chord in both the peak efficiency and near stall cases.

A Numerical Study of Volute Design in Centrifugal Compressor

2001 ◽  
Author(s):  
Weili Yang ◽  
Peter Grant ◽  
James Hitt
Keyword(s):  
Centrifugal Compressor ◽  
Pressure Loss ◽  
Total Pressure ◽  
Numerical Study ◽  
Flow Behavior ◽  
Numerical Results ◽  
Total Pressure Loss ◽  
Pressure Loss Coefficient ◽  
Computational Fluid Dynamics Cfd ◽  
Operating Points

Abstract Our principle goal of this study is to develop a CFD based analysis procedure that could be used to analyze the geometric tradeoffs in scroll geometry when space is limited. In the study, a full centrifugal compressor stage at four different operating points from near surge to near choke is analyzed using Computational Fluid Dynamics (CFD) and laboratory measurement. The study concentrates on scroll performance and its interaction with a vaneless diffuser and impeller. The numerical results show good agreement with test data in scroll circumferential pressure distribution at different ΛAR, total pressure loss coefficient, and pressure distortion at the tongue. The CFD analysis also predicts a reasonable choke point of the stage. The numerical results provide overall flow field in the scroll and diffuser at different operating points. From examining the flow fields, one can have a much better understanding of rather complicated flow behavior such as jet-wake mixing, and choke. One can examine total pressure loss in detail to provide crucial direction for scroll design improvement in areas such as volute tongue, volute cross-section geometry and exit conical diffuser.

CFD Simulations of the Cold Neutron Source at the OPAL Reactor

2020 ◽  
Author(s):  
James L Spedding ◽  
Mark Ho ◽  
Weijian Lu
Keyword(s):  
Neutron Source ◽  
Cold Neutron ◽  
Operating Conditions ◽  
Convergence Time ◽  
Cfd Model ◽  
Cfd Simulations ◽  
Cold Neutron Source ◽  
Order Of Magnitude ◽  
Computational Fluid Dynamics Cfd ◽  
Polyhedral Mesh

Abstract The Open Pool Australian Light-water (OPAL) reactor Cold Neutron Source (CNS) is a 20 L liquid deuterium thermosiphon system which has performed consistently but will require replacement in the future. The CNS deuterium exploits neutronic heating to passively drive the thermosiphon loop and is cryogenically cooled by forced convective helium flow via a heat exchanger. In this study, a detailed computational fluid dynamics (CFD) model of the complete thermosiphon system was developed for simulation. Unlike previous studies, the simulation employed a novel polyhedral mesh technique. Results demonstrated that the polyhedral technique reduced simulation computational requirements and convergence time by an order of magnitude while predicting thermosiphon performance to within 1% accuracy when compared with prototype experiments. The simulation model was extrapolated to OPAL operating conditions and confirmed the versatility of the CFD model as an engineering design and preventative maintenance tool. Finally, simulations were performed on a proposed second-generation CNS design that increases the CNS moderator deuterium volume by 5 L, and results confirmed that the geometry maintains the thermosiphon deuterium in the liquid state and satisfies the CNS design criteria.

scholarly journals Using CFD Simulations to Guide the Development of a New Spray Dryer Design

Processes ◽  
2020 ◽  
Vol 8 (8) ◽  
pp. 932
Author(s):  
Timothy A. G. Langrish ◽  
James Harrington ◽  
Xing Huang ◽  
Chao Zhong
Keyword(s):  
Deposition Process ◽  
Operating Conditions ◽  
Feed Concentration ◽  
Cfd Simulations ◽  
Physical Experiments ◽  
Solids Concentration ◽  
Computational Fluid Dynamics Cfd ◽  
Higher Temperature ◽  
Drying System ◽  
Drying Chamber

A new spray-drying system has been designed to overcome the limitations caused by existing designs. A key feature of the approach has been the systematic use of Computational Fluid Dynamics (CFD) to guide innovation in the design process. An example of an innovation is the development of a box-shaped transitional feature between the bottom of the main drying chamber and the entrance to the secondary chamber. In physical experiments, the box design performed better in all three representative operating conditions, including the current conditions, a higher feed solids concentration (30% solids rather than 8.8%), and a higher inlet drying temperature (230 °C rather than 170 °C). The current conditions showed a 3% increase in yield (solids recovery) while the 30% feed condition improved the yield by 7.5%, and the higher temperature test increased the yield by 13.5%. Statistical analysis showed that there were significant reductions in the wall flux at the high solids feed concentration. The observed deposition in the box was primarily from the predicted particle impacts by an inertial deposition process on the base of the box, which underwent little degradation due to lower temperatures. There is therefore evidence that the box design is a better design alternative under all operating conditions compared with other traditional designs.

Computational aeroelastic analysis of slowed rotors at high advance ratios

2014 ◽  
Vol 118 (1201) ◽  
pp. 297-313 ◽  
Author(s):  
J. de Montaudouin ◽  
N. Reveles ◽  
M. J. Smith
Keyword(s):  
High Speed ◽  
Rotor Blades ◽  
Vortex Interaction ◽  
Blade Loading ◽  
Blade Vortex Interaction ◽  
Aeroelastic Analysis ◽  
Computational Fluid Dynamics Cfd ◽  
Advance Ratio ◽  
Cfd Method ◽  
Model Rotor

Abstract The aerodynamic and aeroelastic behaviour of a rotor become more complex as advance ratios increase to achieve high-speed forward fight. As the rotor blades encounter large regions of cross and reverse flows during each revolution, strong variations in the local Mach regime are encountered, inducing complex elastic blade deformations. In addition, the wake system may remain in the vicinity of the rotor, adding complexity to the blade loading. The aeroelastic behaviour of a model rotor with advance ratios ranging from 0·5 to 2·0 has been evaluated with aerodynamics provided via a computational fluid dynamics (CFD) method. Significant radial blade-vortex interaction can occur at a high advance ratio; the advance ratio at which this occurs is dependent on the rotor configuration. This condition is accompanied by high vibratory loads, peak negative torsion, and peak torsion and in-plane loads. The high vibratory loading increases the sensitivity of the trim model, so that at some high advance ratios the vibratory loads must be filtered to achieve a trimmed state.

Radial Variation in Distortion Transfer and Generation in a Highly Loaded Fan Stage From Near-Stall to Choke

2019 ◽  
Author(s):  
Daniel R. Soderquist ◽  
Andrew D. Orme ◽  
Steven E. Gorrell ◽  
Michael G. List
Keyword(s):  
Performance Prediction ◽  
Total Pressure ◽  
Blade Design ◽  
Local Power ◽  
Inlet Distortion ◽  
Total Temperature ◽  
And Performance ◽  
Transonic Fan ◽  
The Relationship ◽  
Operating Points

Abstract Understanding distortion transfer and generation through fan and compressor blade rows is able to assist in blade design and performance prediction. Using full annulus URANS simulations, the effects of distortion as it passes through the rotor of a transonic fan at five radial locations (10%, 30%, 50%, 70%, and 90% span) are analyzed. The inlet distortion profile is a 90-degree sector with a 15% total pressure deficit. Fourier distortion descriptors are used in this study to quantitatively describe distortion transfer and generation. Results are presented and compared for three operating points (near-stall, design, and choke). These results are used to explain the relationship between inlet total pressure distortion, pressure-induced swirl, total pressure distortion transfer, total temperature distortion generation, and circumferential rotor power variation. It is shown that very large changes in pressure-induced swirl and distortion transfer and generation occur between near-stall and design, but only small changes are seen between design and choke. The greatest changes are shown to be near the tip. Local power variations are shown to correlate with total pressure distortion transfer and total temperature distortion generation.

Impact of Blockage on the Hydrodynamic Performance of Oscillating-Foils Hydrokinetic Turbines

2016 ◽  
Vol 138 (9) ◽  
Author(s):  
Etienne Gauthier ◽  
Thomas Kinsey ◽  
Guy Dumas
Keyword(s):  
Operating Conditions ◽  
Hydrodynamic Performance ◽  
Blockage Ratio ◽  
Cfd Simulations ◽  
Hydrokinetic Turbines ◽  
Marine Energy ◽  
Computational Fluid Dynamics Cfd ◽  
The Impact ◽  
Do So ◽  
Oscillating Foils

This paper describes a study of the impact of confinement on the hydrodynamic performance of oscillating-foils hydrokinetic turbines (OFHT). This work aims to contribute to the development of standards applying to marine energy converters. These blockage effects have indeed to be taken into account when comparing measurements obtained in flumes, towing tanks, and natural sites. This paper provides appropriate correction formula to do so for OFHT based on computational fluid dynamics (CFD) simulations performed at a Reynolds Number Re = 3 × 106 for reduced frequencies between f* = 0.08 and f* = 0.22 considering area-based blockage ratios ranging from ε = 0.2% to 60%. The need to discriminate between the vertical and horizontal confinement and the impact of the foil position in the channel are also investigated and are shown to be of second-order as compared to the overall blockage level. As expected, it is confirmed that the power extracted by the OFHT increases with the blockage level. It is further observed that for blockage ratio of less than ε = 40%, the power extracted scales linearly with ε. The approach proposed to correlate the performance of the OFHT in different blockage conditions uses the correction proposed by Barnsley and Wellicome and assumes a linear relation between the power extracted and the blockage. This technique is shown to be accurate for most of the practical operating conditions for blockage ratios up to 50%.

Numerical Investigation on the Performance of a Regenerative Flow Turbine for Small-Scale Organic Rankine Cycle Systems

2019 ◽  
Vol 141 (9) ◽  
Author(s):  
Ramin Moradi ◽  
Luca Cioccolanti ◽  
Enrico Bocci ◽  
Mauro Villarini ◽  
Massimiliano Renzi
Keyword(s):  
Organic Rankine Cycle ◽  
Rankine Cycle ◽  
Operating Conditions ◽  
Small Scale ◽  
Cfd Analysis ◽  
Cycle Systems ◽  
Mass Flow Rates ◽  
Computational Fluid Dynamics Cfd ◽  
Regenerative Flow ◽  
Operating Points

In this study, the performance characteristics of a regenerative flow turbine (RFT) prototype have been investigated by means of a computational fluid dynamics (CFD) study. The prototype has been initially designed to be used in gas pipelines replacing expansion valves but, because of the intrinsic characteristics of this kind of expander, its use can be extended to other applications like the expansion process in small-scale organic Rankine cycle (ORC) plants. In the first part of this work, the numerical results of the CFD analysis have been validated with the experimental data reported in literature for the same turbine prototype. After the validation of the model, a detailed study has been carried out in order to evaluate specific features of the turbine, focusing the attention on the typical operating conditions of small-scale low-temperature ORC systems. Results have shown that the considered RFT prototype operates with higher isentropic efficiencies (about 32% at 6000 rpm) at lower mass flow rates, while the power output is penalized compared to other operating points. The numerical analysis has also pointed out the high impact of the losses in the leakage flow in the gap between the blade tips and the stripper walls. Therefore, the CFD analysis carried out has provided a thoughtful understanding of the performance of the expander at varying operating conditions and useful insights for the future redesign of this kind of machine for the application in small-scale ORCs.

scholarly journals Intensification of liquid mixing and local turbulence using a fractal injector with staggered conformation

2021 ◽  
Author(s):  
Shuxian Jiang ◽  
Marc-Olivier Coppens ◽  
Jia-Jun WANG
Keyword(s):  
Flow Field ◽  
Operating Conditions ◽  
Cfd Simulations ◽  
Mixing Performance ◽  
Double Ring ◽  
Spatially Distributed ◽  
Field Uniformity ◽  
Reaction Region ◽  
Dissipation Model ◽  
Computational Fluid Dynamics Cfd

Two self-similar, tree-like injectors of the same fractal dimension are compared, demonstrating that other geometric parameters besides dimension play a crucial role in determining mixing performance. In one injector, when viewed from the top, the conformation of branches is eclipsed; in the other one, it is staggered. The flow field and the fractal injector induced mixing performance are investigated through computational fluid dynamics (CFD) simulations. The finite rate/eddy dissipation model (FR/EDM) is modified for fast liquid-phase reactions involving local micromixing. Under the same operating conditions, flow field uniformity and micromixing are improved when a staggered fractal injector is used. This is because of enhanced jet entrainment and local turbulence around the spatially distributed nozzles. Compared with a traditional double-ring sparger, a larger reaction region volume and lower micromixing time are obtained with fractal injectors. Local turbulence around the spatially distributed nozzles in fractal injectors improves reaction efficiency.

High-Fidelity Numerical Analysis of Per-Rev-Type Inlet Distortion Transfer in Multistage Fans—Part II: Entire Component Simulation and Investigation

2010 ◽  
Vol 132 (4) ◽  
Author(s):  
Jixian Yao ◽  
Steven E. Gorrell ◽  
Aspi R. Wadia
Keyword(s):  
Total Pressure ◽  
Navier Stokes ◽  
High Fidelity ◽  
Inlet Distortion ◽  
Unsteady Rans ◽  
Total Temperature ◽  
Computational Fluid Dynamics Cfd ◽  
Last Stage ◽  
Remarkable Agreement ◽  
Engine Development

Part I of this paper validated the ability of the unsteady Reynolds-Averaged Navier-Stokes (RANS) solver PTURBO to accurately simulate distortion transfer and generation through selected blade rows of two multistage fans. In this part, unsteady RANS calculations were successfully applied to predict the 1/rev inlet total pressure distortion transfer in the entirety of two differently designed multistage fans. This paper demonstrates that high-fidelity computational fluid dynamics (CFD) can be used early in the design process for verification purposes before hardware is built and can be used to reduce the number of distortion tests, hence reducing engine development cost. The unsteady RANS code PTURBO demonstrated remarkable agreement with the data, accurately capturing both the magnitude and the profile of total pressure and total temperature measurements. Detailed analysis of the flow physics identified from the CFD results has led to a thorough understanding of the total temperature distortion generation and transfer mechanism, especially for the spatial phase difference of total pressure and total temperature profiles. The analysis illustrates that the static parameters are more revealing than their stagnation counterpart and that pressure and temperature rise are more revealing while the pressure and temperature ratio could be misleading. The last stage is effectively throttled by the inlet distortion even though the overall engine throttle remains unchanged. The total temperature distortion generally grows as flow passes through the fan stages.

Further Investigation of the Influence of Real-World Blade Profile Variation on the Aerodynamic Performance of Transonic Nozzle Guide Vanes

2011 ◽  
Author(s):  
J. Ilott ◽  
A. Asghar ◽  
W. D. E. Allan ◽  
R. Woodason
Keyword(s):  
Total Pressure ◽  
Operating Conditions ◽  
Trailing Edge ◽  
Experimental Conditions ◽  
Pressure Losses ◽  
Low Pressure Turbine ◽  
Turbine Vanes ◽  
Computational Fluid Dynamics Cfd ◽  
Nozzle Guide ◽  
Nozzle Guide Vanes

This paper addresses the issue of aerodynamic consequences of variations in airfoil profile. An analysis of new and repaired airfoils was used to synthesize profiles representative of specific repair types. Five variations of a reference new low pressure turbine vane were obtained by changing the characteristic parameters of trailing-edge tweaking and laminate-repair methods used to refurbish turbine vanes. Flow visualization of shock structure and total pressure measurements were made by experimentation in a cascade rig and by calculations through Computational Fluid Dynamics (CFD). The performance of the modified profiles was compared with that of the reference new vane. The total pressure losses increased when the profile was bent at the trailing edge towards the pressure side. The losses for synthesized laminate repair profiles increased with an increase in the thickness of laminate repair. The numerical results were used to supplement experimental results in cases where the experimental conditions were not representative of typical design operating conditions.

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