Challenges Associated With Replicating Rotor Blade Deposition in a Non-Rotating Annular Cascade

2019 ◽  
Author(s):  
Christopher P. Bowen ◽  
Ali Ameri ◽  
Jeffrey P. Bons
Keyword(s):  
Flow Field ◽  
Incidence Angle ◽  
Rotor Blades ◽  
Absolute Pressure ◽  
Inlet Section ◽  
Turbine Engine ◽  
Model Flow ◽  
Annular Cascade ◽  
The Impact ◽  
Relative Flow

Abstract A computational analysis is performed to determine if particulate impact events on the external surfaces of gas turbine engine rotor blades can be faithfully replicated in an experimental rotor cascade. The General Electric (GE) Energy Efficient Engine (E3) first-stage turbine flow-field at cruise conditions is first solved using a steady state explicit mixing plane approach with non-reflecting treatment. To model flow in the cascade, a single E3 rotor periodic domain is then constructed with an inlet section matching the relative flow incidence angle from the mixing plane calculation. The mass-averaged relative flow conditions at the inlet and outlet of the mixing plane rotor section are imposed on the cascade boundaries and a steady solution is found. Particles with diameters ranging from 1 to 25 μm are tracked through each fluid domain using a Lagrangian approach, and the OSU Deposition Model is implemented to dictate the sticking and rebounding action when particles interact with solid surfaces. The impact locations on the blade are compared between the rotating (mixing plane) and stationary (cascade) cases. It is discovered that both the locations and parameters of the particle impacts in the cascade vary significantly from the engine environment. For smaller particles, this deviation is credited to a stronger upstream influence of the blade on the cascade flow-field. As particle size increases, this effect tapers off, and the differences in deposition are instead driven by the interaction of the full-stage vane with the particles. The lack of a vane in the cascade causes drastically different particle inlet vectors over the rotor than are seen in the engine setting. The radial differences of particle impact locations are explored, and the role that absolute pressure plays is considered.

Challenges Associated With Replicating Rotor Blade Deposition in a Non-Rotating Annular Cascade

2020 ◽  
Vol 142 (9) ◽  
Author(s):  
Christopher P. Bowen ◽  
Ali Ameri ◽  
Jeffrey P. Bons
Keyword(s):  
Flow Field ◽  
Incidence Angle ◽  
Rotor Blades ◽  
Solid Surfaces ◽  
Inlet Section ◽  
Turbine Engine ◽  
Model Flow ◽  
Annular Cascade ◽  
Impact Events ◽  
Relative Flow

Abstract A computational analysis is performed to determine if particulate impact events on the external surfaces of gas turbine engine rotor blades can be faithfully replicated in an experimental rotor cascade. The general electric (GE) energy efficient engine (E3) first-stage turbine flow-field at cruise conditions is first solved using a steady-state explicit mixing plane (MP) approach. To model flow in the cascade, a single E3 rotor periodic domain is then constructed with an inlet section matching the relative flow incidence angle from the mixing plane calculation. The mass-averaged relative flow conditions at the inlet and outlet of the mixing plane rotor section are imposed on the cascade boundaries and a steady solution is found. Particles with diameters ranging from 1 to 25 µm are tracked through each domain and the OSU deposition model is implemented to dictate the sticking and rebounding action of particles impacting solid surfaces. It is discovered that both the locations and parameters of the impacts in the cascade vary significantly from the engine environment. For smaller particles, this is credited to a stronger upstream influence of the blade on the cascade flow-field. As size increases, differences in deposition are instead driven by the interaction of the full-stage vane with the particles. The lack of a vane in the cascade causes drastically different particle inlet vectors over the rotor than are seen in the engine setting. The radial differences of particle impact locations are explored, and the role that pressure plays is considered.

An Impact of Various Shroud Bleed Slot Configurations and Cavity Vanes on Compressor Map Width and the Inducer Flow Field

2013 ◽  
Vol 135 (4) ◽  
Author(s):  
Subenuka Sivagnanasundaram ◽  
Stephen Spence ◽  
Juliana Early ◽  
Bahram Nikpour
Keyword(s):  
Flow Field ◽  
Incidence Angle ◽  
Pressure Ratio ◽  
Leading Edge ◽  
Operating Conditions ◽  
Choked Flow ◽  
Recirculating Flow ◽  
Heavy Duty Diesel ◽  
Compressor Map ◽  
The Impact

This paper describes an investigation of map width enhancement and a detailed analysis of the inducer flow field due to various bleed slot configurations and vanes in the annular cavity of a turbocharger centrifugal compressor. The compressor under investigation is used in a turbocharger application for a heavy duty diesel engine of approximately 400 hp. This investigation has been undertaken using a computational fluid dynamics (CFD) model of the full compressor stage, which includes a manual multiblock-structured grid generation method. The influence of the bleed slot flow on the inducer flow field at a range of operating conditions has been analyzed, highlighting the improvement in surge and choked flow capability. The impact of the bleed slot geometry variations and the inclusion of cavity vanes on the inlet incidence angle have been studied in detail by considering the swirl component introduced at the leading edge by the recirculating flow through the slot. Further, the overall stage efficiency and the nonuniform flow field at the inducer inlet have been also analyzed. The analysis revealed that increasing the slot width has increased the map width by about 17%. However, it has a small impact on the efficiency, due to the frictional and mixing losses. Moreover, adding vanes in the cavity improved the pressure ratio and compressor performance noticeably. A detail analysis of the compressor with cavity vanes has also been presented.

Unsteady Flow Field and Noise Generation in a Centrifugal Pump Impeller With a Vaneless Diffuser

2005 ◽  
Author(s):  
Giorgio Pavesi ◽  
Guido Ardizzon ◽  
Giovanna Cavazzini
Keyword(s):  
Flow Field ◽  
Acoustic Radiation ◽  
Wake Flow ◽  
Test Model ◽  
Centrifugal Pumps ◽  
Vaneless Diffuser ◽  
Pump Impeller ◽  
Model Flow ◽  
Return Channel ◽  
The Impact

To improve understanding of the phenomena of stall in centrifugal pumps, extensive research was conducted to investigate the impact on flow field instabilities and the noise generated in a pump equipped with a diffuser. A pump fitted with a vaneless diffuser and a return channel was used as the test model. Flow velocity was measured at the pump and at diffuser inflow to establish a link between the flow field structure and acoustic radiation. Activity was based upon the cross spectral analysis of output signals from piezoelectric transducers placed flush with the wall at the inflow and outflow of the pump, and 3D fully-viscous unsteady computations. Results showed the jet-wake flow pattern induced an unstable vortex, which influenced flow discharging from the adjacent passage and destabilised jet-wake flow in the passage. Consequently, periodic fluctuations were seen at impeller discharge which were found to be coherent from blade to blade and possessed a rich harmonic content. With the exception of the total pressure in the far field, the pressure frequency scattering by the pump was found to be consistent when compared to the experimental and analytic results.

An Impact of Various Shroud Bleed Slot Configurations and Cavity Vanes on Compressor Map Width and the Inducer Flow Field

2011 ◽  
Author(s):  
Subenuka Sivagnanasundaram ◽  
Stephen Spence ◽  
Juliana Early ◽  
Bahram Nikpour
Keyword(s):  
Flow Field ◽  
Incidence Angle ◽  
Pressure Ratio ◽  
Leading Edge ◽  
Operating Conditions ◽  
Choked Flow ◽  
Recirculating Flow ◽  
Heavy Duty Diesel ◽  
Compressor Map ◽  
The Impact

This paper describes an investigation of map width enhancement and a detailed analysis of the inducer flow field due to various bleed slot configurations and vanes in the annular cavity of a turbocharger centrifugal compressor. The compressor under investigation is used in a turbocharger application for a heavy duty diesel engine of approximately 400hp. This investigation has been undertaken using a CFD model of the full compressor stage which includes a manual multi-block structured grid generation method. The influence of the bleed slot flow on the inducer flow field at a range of operating conditions has been analysed, highlighting the improvement in surge and choked flow capability. The impact of the bleed slot geometry variations and the inclusion of cavity vanes on the inlet incidence angle have been studied in detail by considering the swirl component introduced at the leading edge by the recirculating flow through the slot. Further, the overall stage efficiency and the non-uniform flow field at the inducer inlet have been also analysed. The analysis revealed that increasing the slot width has increased the map width by about 17%. However, it has a small impact on the efficiency due to the frictional and mixing losses. Moreover, adding vanes in the cavity improved the pressure ratio and compressor performance noticeably. A detail analysis of the compressor with cavity vanes has also been presented.

Investigation of Fan Rotor Interaction With Pressure Disturbance Produced by Downstream Pylon

2013 ◽  
Author(s):  
Tomonori Enoki ◽  
Hidekazu Kodama ◽  
Shinya Kusuda
Keyword(s):  
Flow Field ◽  
Three Dimensional ◽  
Numerical Results ◽  
Rotor Blades ◽  
Flow Structures ◽  
Coupled Analysis ◽  
Unsteady Forces ◽  
Rotor Stator Interaction ◽  
The Impact ◽  
Potential Pressure

This paper presents an investigation of fan rotor interaction with potential pressure disturbances produced by a downstream pylon. Three-dimensional unsteady viscous analyses are performed for two fan rotor-stator-pylon configurations with different axial gaps between the stator and the pylon, and compared with the experimental results. To clarify the impact of the rotor-pylon interaction on the potential pressure flow field, a numerical analysis for the configuration in which a fan rotor is removed is also performed and compared with the numerical results with fan rotor. Actuator disk analyses are also performed to interpret the flow structures observed in the experiments and the numerical results. It is found that a fan rotor-stator interaction also exists in the fan flow field, and this may impact on the upstream propagating potential flow that dominates the unsteady forces acting on the rotor blades. A coupled analysis between fan rotor and stator is essential to accurately predict the unsteady blade force.

Analysis and Evaluation of the Impact of Different Blade Loadings on a 2-Stage Turbine With Shrouded Blades

2011 ◽  
Author(s):  
Dieter Bohn ◽  
Stephan Schwab ◽  
Michael Sell
Keyword(s):  
Flow Field ◽  
Gas Turbines ◽  
Labyrinth Seal ◽  
Rotor Blades ◽  
Analysis And Evaluation ◽  
Passage Vortex ◽  
Flow Phenomena ◽  
Two Stages ◽  
Shrouded Rotor ◽  
The Impact

An important goal in the development of turbine bladings is to increase the efficiency in order to achieve an optimized use of energy resources. For that purpose a detailed understanding of flow phenomena is required. This paper presents an experimental investigation of the impact of varying blade loadings on the flow field and leakage flow. The investigations were conducted on a 2-stage axial turbine at the Institute of Steam- and Gas Turbines, RWTH Aachen University. The flow field for different blade loadings has been determined at the inlet and outlet as well as between the two stages. Consequently, the inhomogeneity at the outlet of each stage, depending on the blade loading, may be investigated. The homogeneity at the outlet has been evaluated by using the secondary kinetic energy coefficient and the formation of the passage vortex has therefore been emphasized. Furthermore, the loading impact on the leakage mass flow and the leakage main flow interaction has been estimated. On this account, the pressure loss in each cavity within the labyrinth seal of the first shrouded rotor blades is detected. The impact on the efficiency of different loadings has moreover been determined. The efficiency has been ascertained by using 5-hole probes and temperature probes after each stage. The investigations mentioned above have been conducted on a 2D-blade profile and serve as a baseline for future profiled end wall studies. The goal of the endwall contoured blades shall reduce the passage vortex and with it, the under- and overturning which ultimately leads to a more homogeneous outflow from the stage.

A Numerical Investigation of the Impact of Part-Span Connectors on the Flow Field in a Linear Cascade

2017 ◽  
Author(s):  
C. Brüggemann ◽  
M. Schatz ◽  
D. M. Vogt ◽  
F. Popig
Keyword(s):  
Flow Field ◽  
Numerical Investigation ◽  
Incidence Angle ◽  
Wake Flow ◽  
Analytical Models ◽  
Axial Position ◽  
Design Parameters ◽  
Working Fluid ◽  
Linear Cascade ◽  
The Impact

This paper presents a numerical investigation of the impact of different part-span connector (PSC) configurations on the flow field in a turbine passage. For this purpose a linear cascade based on a profile section of a typical reaction blade used in industrial steam turbines was modeled and 3D simulations with varying size, shape, axial position and yaw incidence angle of the PSC were performed. Air modeled as ideal gas was chosen as the working fluid. Apart from a sensitivity study of the above mentioned parameters on the losses incurred by PSCs based on the numerical results, a detailed investigation of the flow field was carried out to highlight the interaction with the incoming flow. Moreover, the variation of the flow field behind the cascade was examined to assess the impact on the subsequent blade row. It is shown that depending on the geometry and the position of the PSC, different vortex structures are established in the wakes. These wakes interact with the main flow in the passage, thus influencing both dissipation and the downstream flow field. Major changes of the wake flow character and extent could be observed. Comparisons of the CFD results against commonly used analytical loss correlations for PSC revealed large differences, especially as certain parameters such as the yaw incidence angle are generally not considered by the latter. As a consequence, the analytical models need to be improved and extended. The results of this study indicate that the possibility of reducing the losses incurred by PSC by careful selection of design parameters within the design space dictated by its mechanical constraints.

Unsteady Effects on Transonic Turbine Blade-Tip Heat Transfer

2012 ◽  
Vol 134 (6) ◽  
Author(s):  
Nicholas R. Atkins ◽  
Steven J. Thorpe ◽  
Roger W. Ainsworth
Keyword(s):  
Heat Transfer ◽  
Flow Field ◽  
Flow Distribution ◽  
Potential Interaction ◽  
Rotor Blades ◽  
Time Varying ◽  
Trailing Edge ◽  
Blade Tip ◽  
Transonic Turbine ◽  
The Impact

In a gas turbine engine the blade tips of the high-pressure turbine are exposed to high levels of convective heat transfer, because of the so-called tip-leakage phenomenon. The blade-lift distribution is known to control the flow distribution in the blade–tip gap. However, the interaction between upstream nozzle guide vanes and the rotor blades produces a time-varying flow field that induces varying flow conditions around the blade and within the tip gap. Extensive measurements of the unsteady blade-tip heat transfer have been made in an engine representative transonic turbine. These include measurements along the mean camber line of the blade tip, which have revealed significant variation in both time-mean and time-varying heat flux. The influences of potential interaction and the vane trailing edge have been observed. Numerical calculations of the turbine stage using a Reynolds-averaged-Navier-Stokes-based computational fluid dynamics code have also been conducted. In combination with the experimental results, these have enabled the time-varying flow field to be probed in the blade-relative frame of reference. This has allowed a deeper analysis of the unsteady heat-transfer data, and the quantification of the impact of vane potential field and vane trailing edge interaction on the tip-region flow and heat transfer. In particular, the separate effects of time-varying flow temperature and heat-transfer coefficient have been established.

Assessment of wind field generation methods on predicted wind-turbine power production using a free vortex filament wake approach

2021 ◽  
pp. 1-15
Author(s):  
Hamidreza Abedi ◽  
Bastian Nebenführ ◽  
Lars Davidson
Keyword(s):  
Flow Field ◽  
Turbulent Flow ◽  
Wind Turbine ◽  
Wind Field ◽  
Power Production ◽  
Rotor Blades ◽  
Low Frequencies ◽  
The Mean ◽  
The Impact ◽  
Simulation Time

Abstract The generated power and thrust of a wind turbine strongly depend on the flow field around the turbine. In the present study, three different inflow methods, i.e., a time series (TS) from Large-Eddy Simulation (LES) of atmospheric boundary layer flow field, a synthetic turbulent flow field using the Mann model (MM) and a steady-state mean wind profile with shear (PL), are integrated with the free vortex filament wake method to investigate the effect of wind field generation methods on the wind turbine performance where the impact of the turbine and the trailing wake vortices on the turbulent flow fields are ignored. For this purpose, an in-house Vortex Lattice Free Wake (VLFW) code is developed and used to predict the aerodynamic loads on rotor blades. The NREL 5-MW reference wind turbine is used for the VLFW simulations. For a fair assessment of different inflow generation methods on power production of a wind turbine, it is not sufficient that the generated wind fields employed in the TS and MM methods, have the same streamwise mean velocity and turbulence intensity at hub height. Instead, the generated inflows must have equivalent power-spectral densities especially at low frequencies since the rotor blades essentially respond to the large-scale fluctuations (macroscopic scales) rather than small-scale fluctuations (microscopic scales). A faster energy decay rate of LES inflow leads to a higher en-ergy content in the TS method at low frequencies (associated with the macroscopic dynamics of the rotor blades). This extra kinetic energy results in a slightly higher mean power production while using the TS method although the inflow conditions at hub height/rotor plane are the same for both the TS and MM methods. Moreover, the impact of simulation time (the length of time integration) on the power production of a wind turbine (exposed to an unsteady inflow) must be taken into account. A short simulation time remarkably affects the mean wind speed over the rotor area for identical turbulent inflows. For Taylor’s hypothesis application using a single LES flow field, the results show a significant difference in the mean powers corresponding to the different realizations due to large turbulent fluctuations.

Investigation of Hydrodynamic Focusing in a Microfluidic Coulter Counter Device

2012 ◽  
Vol 134 (8) ◽  
Author(s):  
Muheng Zhang ◽  
Yongsheng Lian ◽  
Cindy Harnett ◽  
Ellen Brehob
Keyword(s):  
Flow Field ◽  
Flow Rate ◽  
Coulter Counter ◽  
Hydrodynamic Focusing ◽  
Relative Flow Rate ◽  
Advection Diffusion Equation ◽  
Sample Stream ◽  
Voltage Signal ◽  
The Impact ◽  
Relative Flow

The Coulter technique enables rapid analysis of particles or cells suspended in a fluid stream. In this technique, the cells are suspended in an electrically conductive solution, which is hydrodynamically focused by nonconducting sheath flows. The cells produce a characteristic voltage signal when they interrupt an electrical path. The population and size of the cells can be obtained through analyzing the voltage signal. In a microfluidic Coulter counter device, the hydrodynamic focusing technique is used to position the conducting sample stream and the cells and also to separate close cells to generate distinct signals for each cell and avoid signal jam. The performance of hydrodynamic focusing depends on the relative flow ratio between the sample stream and sheath stream. We use a numerical approach to study the hydrodynamic focusing in a microfluidic Coulter counter device. In this approach, the flow field is described by solving the incompressible Navier-Stokes equations. The sample stream concentration is modeled by an advection-diffusion equation. The motion of the cells is governed by the Newton-Euler equations of motion. Particle motion through the flow field is handled using an overlapping grid technique. A numerical model for studying a microfluidic Coulter counter has been validated. Using the model, the impact of relative flow rate on the performance of hydrodynamic focusing was studied. Our numerical results show that the position of the sample stream can be controlled by adjusting the relative flow rate. Our simulations also show that particles can be focused into the stream and initially close particles can be separated by the hydrodynamic focusing. From our study, we conclude that hydrodynamic focusing provides an effective way to control the position of the sample stream and cells and it also can be used to separate cells to avoid signal jam.

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