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.

Numerical and Experimental Investigations on a Centrifugal Pump With and Without a Vaned Diffuser

2004 ◽  
Author(s):  
G. Pavesi ◽  
G. Ardizzon ◽  
G. Cavazzini
Keyword(s):  
Flow Field ◽  
Acoustic Radiation ◽  
Pressure Sensors ◽  
Wake Flow ◽  
Experimental Investigations ◽  
Test Model ◽  
Centrifugal Pumps ◽  
Vaned Diffuser ◽  
Return Channel ◽  
The Impact

Extensive research on centrifugal pumps was designed to investigate the impact of a diffuser on flow field instabilities and the noise generated by these instabilities. Activity was based upon a coupled use of measurements and 3D fully-viscous, unsteady computations. The test model was a seven-blade pump-turbine, used as a pump. Fitted with a vaneless diffuser, and two vaned diffusers with twenty-two adjustable, guide-diffuser vanes, and a return channel with eleven continuous vanes. Diffusers were equipped with eight pressure sensors in the adjustable guide-diffuser vanes, and nineteen pressure taps in the continuous vanes. To establish a link between the flow field structure and acoustic radiation, flow velocity was measured in the vaneless part of the diffuser. Piezoelectric transducers, placed flush with the wall, were used to measure pressure fluctuation inside the blade channels. Signal analysis was carried out in the frequency domain. Results showed the jet-wake flow pattern induced an unstable vortex, which influenced flow discharging from the adjacent passage, and destabilized jet-wake flow in the passage. This instability caused a periodic fluctuation at the discharge of the impeller. Fluctuations were found to be coherent from blade to blade, and to possess a rich harmonic content. Numerical analyses did not fully confirm these results.

Adiabatic Effectiveness and Flow Field Measurements in a Realistic Effusion Cooled Lean Burn Combustor

2015 ◽  
Vol 138 (3) ◽  
Author(s):  
Antonio Andreini ◽  
Riccardo Becchi ◽  
Bruno Facchini ◽  
Lorenzo Mazzei ◽  
Alessio Picchi ◽  
...  
Keyword(s):  
Flow Field ◽  
Field Measurements ◽  
Injection System ◽  
Wall Region ◽  
Test Model ◽  
Nox Emissions ◽  
Lean Burn ◽  
Experimental Apparatus ◽  
Adiabatic Effectiveness ◽  
The Impact

Over the last ten years, there have been significant technological advances toward the reduction of NOx emissions from civil aircraft engines, strongly aimed at meeting stricter and stricter legislation requirements. Nowadays, the most prominent way to meet the target of reducing NOx emissions in modern combustors is represented by lean burn swirl stabilized technology. The high amount of air admitted through a lean burn injection system is characterized by very complex flow structures such as recirculations, vortex breakdown, and precessing vortex core (PVC) that may deeply interact in the near wall region of the combustor liner. This interaction makes challenging the estimation of film cooling distribution, commonly generated by slot and effusion systems. The main purpose of the present work is the characterization of the flow field and the adiabatic effectiveness due to the interaction of swirling flow, generated by real geometry injectors, and a liner cooling scheme made up of a slot injection and an effusion array. The experimental apparatus has been developed within EU project LEMCOTEC (low emissions core-engine technologies) and consists of a nonreactive three-sectors planar rig; the test model is characterized by a complete cooling system and three swirlers, replicating the geometry of a GE Avio PERM (partially evaporated and rapid mixing) injector technology. Flow field measurements have been performed by means of a standard 2D PIV (particle image velocimetry) technique, while adiabatic effectiveness maps have been obtained using PSP (pressure sensitive paint) technique. PIV results show the effect of coolant injection in the corner vortex region, while the PSP measurements highlight the impact of swirled flow on the liner film protection separating the contribution of slot and effusion flows. Furthermore, an additional analysis, exploiting experimental results in terms of heat transfer coefficient, has been performed to estimate the net heat flux reduction (NHFR) on the cooled test plate.

Development of Steam Chest With Valve for Steam Extraction in Cogeneration

2014 ◽  
Author(s):  
Zhenzhen Hao ◽  
Puning Jiang ◽  
Xingzhu Ye ◽  
Gang Chen ◽  
Yifeng Hu ◽  
...  
Keyword(s):  
Flow Field ◽  
Pressure Distribution ◽  
Fourier Transforms ◽  
Operating Conditions ◽  
Mode Analysis ◽  
Technical Solution ◽  
Test Model ◽  
Aerodynamic Forces ◽  
Valve Disc ◽  
The Impact

Cogeneration has been identified as a key technical solution to improve environment, by reducing the impact of global climate change and reducing local emissions, such as particulates, sulphur and nitrogen oxides. In cogeneration, a certain pressure of steam has to be extracted from steam turbine. A mechanical device shall be used to maintain the pressure of the extracted steam. In this paper a new steam chest with valve used for cogeneration which is installed in the steam flow is introduced. Different amount of steam extractions need different valve openings. In order to obtain these several valve openings in typical operating conditions, CFD-program is used to simulate the flow path in the steam chest. The pressure distribution on the surface of valve disc can be calculated through CFD method, and corresponding steady aerodynamic forces and torques can be calculated by integral. Pulsatile flow will change the forces and moments acting on the valve discs with time constantly. Frequency spectrograms of the aerodynamic forces are obtained by using the fast Fourier transforms and compared to the characteristic frequencies of the valve disc obtained by mode analysis. For the purpose of validating the accuracy of CFD model, a test with test model scale of 1:5 has been designed. In the test, the pressure distribution on the valve disc surface and the flow field in the steam chest are acquired respectively by the method PSP (Pressure-Sensitive Paint) and PIV (Particle Image Velocimetry). CFD calculations and experimental results have been compared and it is shown that CFD calculations using K-ε turbulence model has satisfactory precision to calculate the pressure distribution, flow field and the torques.

Aerodynamic instabilities modeling under asymmetric boundary in a centrifugal compressor for turbocharger

2022 ◽  
pp. 095440702110726
Author(s):  
Chenxing Hu ◽  
Xue Li ◽  
Siyu Zheng
Keyword(s):  
Boundary Conditions ◽  
Centrifugal Compressor ◽  
Reverse Flow ◽  
Pressure Ratio ◽  
Safety Margin ◽  
Wake Flow ◽  
Wave Number ◽  
Vaneless Diffuser ◽  
The Impact ◽  
Continuous Adjoint

The increasing demand for compression systems with high pressure ratio and wide safety margin has set new prerequisites for designers to meet the industrial needs without increasing the manufacturing costs excessively. In this work, the turbulent stability of the vaneless diffuser of the centrifugal compressor was analyzed. Unsteady Reynolds-averaged numerical simulations of the isolated diffuser and full annular diffuser with or without circumferential asymmetric boundary conditions downstream were performed. And a continuous adjoint approach was adopted, which is rarely applied in the stability analysis of compressor flow. Then, the origin of instability under different inflow and outflow conditions was sought with a sensitivity analysis. The prediction of the growth rate reveals that the flow near the shroud dominates the global stability of the diffuser. When connected with an impeller in the upstream direction, the most unstable region is localized at the backflow regions near the outlet. The wave number, however, is altered under the impact of the jet-wake flow. When connected to a circumferential asymmetric condition, the structural sensitivity of the vaneless diffuser with a radius ratio of 1.53 indicates that the interaction between the inlet reverse flow and outlet backflow is responsible for the occurrence of stall. The most unstable regions are localized at the region 90°–135° away from the volute tongue. The present work mainly contributes to the instabilities identification with novel sensitivity methods under asymmetric boundary conditions.

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.

scholarly journals Effect of the Extended Rigid Flapping Trailing Edge Fringe on an S833 Airfoil

2022 ◽  
Vol 12 (1) ◽  
pp. 444
Author(s):  
Hongtao Yu ◽  
Zifeng Yang
Keyword(s):  
Flow Field ◽  
Flow Characteristics ◽  
Aerodynamic Performance ◽  
Substantial Effect ◽  
Wake Flow ◽  
Trailing Edge ◽  
Large Vortex ◽  
2D Numerical Simulation ◽  
Angular Amplitude ◽  
The Impact

A 2D numerical simulation was conducted to investigate the effect of an extended rigid trailing edge fringe with a flapping motion on the S833 airfoil and its wake flow field, as an analogy of an owl’s wing. This study aims to characterize the influence of the extended flapping fringe on the aerodynamic performance and the wake flow characteristics downstream of the airfoil. The length (Le) and flapping frequencies (fe) of the fringe are the key parameters that dominate the impact on the airfoil and the flow field, given that the oscillation angular amplitude is fixed at 5°. The simulation results demonstrated that the airfoil with an extended fringe of 10% of the chord at a flapping frequency of fe = 110 Hz showed a substantial effect on the pressure distribution on the airfoil and the flow characteristics downstream of the airfoil. An irregular vortex street was predicted downstream, thus causing attenuations of the vorticities, and shorter streamwise gaps between each pair of vortices. The extended flapping fringe at a lower frequency than the natural shedding vortex frequency can effectively break the large vortex structure up into smaller scales, thus leading to an accelerated attenuation of vorticities in the wake.

Flow Field in the Secondary, Seal-Containing Passages of Centrifugal Pumps

1993 ◽  
Vol 115 (4) ◽  
pp. 702-709 ◽  
Author(s):  
E. A. Baskharone ◽  
S. J. Hensel
Keyword(s):  
Flow Field ◽  
Flow Model ◽  
Computational Domain ◽  
Centrifugal Pumps ◽  
Galerkin Finite Element Method ◽  
Hydraulic Pump ◽  
Galerkin Finite Element ◽  
Swirl Velocity ◽  
Through Flow ◽  
The Impact

This paper illustrates the impact of seal configuration on the through-flow leakage in centrifugal pumps with shrouded impellers. The flow model is based on the Petrov-Galerkin finite element method, and the computational domain permits the primary/secondary flow interaction at both ends of the clearance gap. The model is applied to a hydraulic pump with two different seal configurations for the purpose of comparison. The computed results show a strong dependency of the leakage flow percentage and swirl-velocity retention on the overall shape of the shroud-to-housing passage including, in particular, the seal geometry. The results are generally consistent with documented observations and measurements in similar pump stages. From a rotordynamic standpoint, the current computational model conceptually provides the centered-rotor “zeroth-order” flow field for existing perturbation models of fluid/rotor interaction. The flow model is applied to two different secondary passage configurations of a centrifugal pump, and the results used in interpreting existing rotordynamic data concerning the same passage configurations.

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.

scholarly journals Aerodynamic Characteristics of Isolated Loaded Tires with Different Tread Patterns: Experiment and Simulation

2021 ◽  
Vol 34 (1) ◽  
Author(s):  
Haichao Zhou ◽  
Zhen Jiang ◽  
Guolin Wang ◽  
Shupei Zhang
Keyword(s):  
Flow Field ◽  
Aerodynamic Drag ◽  
Flow Direction ◽  
Air Flow ◽  
Flow Characteristics ◽  
Aerodynamic Characteristics ◽  
Test Model ◽  
Pressure Coefficients ◽  
Pressure Area ◽  
The Impact

AbstractThe current research of tire aerodynamics mainly focus on the isolated and simplified tread tire. Compared with the real complex pattern tire, the tread pattern structure and deformed profile of a loaded tire has a greatly influence on tire aerodynamic drag. However, the mechanisms of the isolated loaded tires with different tread patterns effects on the aerodynamic drag are subjects worthy of discussion. The purpose of this study is to experimentally and computationally investigate the aerodynamic characteristics of three tires 185/65 R14 with different patterns under loaded. A wind tunnel test model was first established using three-dimensional (3D) printing with a ratio of 1:1, and the pressure coefficients Cp of the three tires with different patterns are measured. The paper then conducted computational fluid dynamics (CFD) simulations for analyzing the pressure and flow characteristics. The accuracy of CFD simulation is verified by comparing the simulation results with the test results of pressure coefficients Cp, and they are of good consistency. While, the general analysis of pressure coefficients Cp results of the three tires indicates high-pressure area on the windward surface, and occurrence of low-pressure area on the leeward surface, the pressure coefficients Cp of all three tires decreased firstly and then increased along in the air flow direction. The authors finally analyzed the effect of tread patterns on the flow field around the tire and revealed the differences between flow characteristics and aerodynamic drag. The results show that, angle of tire lateral groove has great effect on the flow field characteristics such that; the more the angle of lateral groove agrees with the air flow direction, the less the flow separation and flow vortices, and a minimum observable aerodynamic drag. The research provides a guidance for the design of low aerodynamic drag tires, and helps to illustrate the impact of tire aerodynamics on the car body in the future.

Adiabatic Effectiveness and Flow Field Measurements in a Realistic Effusion Cooled Lean Burn Combustor

2015 ◽  
Author(s):  
Antonio Andreini ◽  
Riccardo Becchi ◽  
Bruno Facchini ◽  
Lorenzo Mazzei ◽  
Alessio Picchi ◽  
...  
Keyword(s):  
Flow Field ◽  
Field Measurements ◽  
Injection System ◽  
Wall Region ◽  
Test Model ◽  
Nox Emissions ◽  
Lean Burn ◽  
Experimental Apparatus ◽  
Adiabatic Effectiveness ◽  
The Impact

Over the last ten years there have been significant technological advances toward the reduction of NOx emissions from civil aircraft engines, strongly aimed at meeting stricter and stricter legislation requirements. Nowadays, the most prominent way to meet the target of reducing NOx emissions in modern combustors is represented by lean burn swirl stabilized technology. The high amount of air admitted through a lean-burn injection system is characterized by very complex flow structures such as recirculations, vortex breakdown and precessing vortex core, that may deeply interact in the near wall region of the combustor liner. This interaction makes challenging the estimation of film cooling distribution, commonly generated by slot and effusion systems. The main purpose of the present work is the characterization of the flow field and the adiabatic effectiveness due to the interaction of swirling flow, generated by real geometry injectors, and a liner cooling scheme made up of a slot injection and an effusion array. The experimental apparatus has been developed within EU project LEMCOTEC and consists of a non-reactive three sectors planar rig; the test model is characterized by a complete cooling system and three swirlers, replicating the geometry of a GE Avio PERM (Partially Evaporated and Rapid Mixing) injector technology. Flow field measurements have been performed by means of a standard 2D PIV (Particle Image Velocimetry) technique, while adiabatic effectiveness maps have been obtained using PSP (Pressure Sensitive Paint) technique. PIV results show the effect of coolant injection in the corner vortex region, while the PSP measurements highlight the impact of swirled flow on the liner film protection separating the contribution of slot and effusion flows. Furthermore an additional analysis, exploiting experimental results in terms of heat transfer coefficient, has been performed to estimate the net heat flux reduction (NHFR) on the cooled test plate.

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