We present the application of the Nonuniform Fast Fourier Transform (NUFFT) to the pseudo-spectral Eulerian–Lagrangian direct numerical simulation of particle-laden flows. In the two-way coupling regime, when the particle feedback on the flow is taken into account, a spectral method requires not only the interpolation of the flow fields at particle positions, but also the Fourier representation of the particle back-reaction on the flow fields on a regular grid. Even though the direct B-spline interpolation is a well-established tool, to the best of our knowledge the reverse projection scheme has never been used, replaced by less accurate linear reverse interpolation or Gaussian regularization. We propose to compute the particle momentum and temperature feedback on the flow by means of the forward NUFFT, while the backward NUFFT is used to perform the B-spline interpolation. Since the backward and forward transformations are symmetric and the (non local) convolution computed in physical space is removed in Fourier space, this procedure satisfies all constraints for a consistent interpolation scheme, and allows an efficient implementation of high-order interpolations. The resulting method is applied to the direct numerical simulation of a forced and isotropic turbulent flow with different particle Stokes numbers in the two-way coupling regime. A marked multifractal scaling is observed in the particle statistics, which implies that the feedback from the particles on the fields is far from being analytic and therefore only high-order methods, like the one here proposed, can provide an accurate representation.
{"title":"APPLICATION OF THE NONUNIFORM FAST FOURIER TRANSFORM TO THE DIRECT NUMERICAL SIMULATION OF TWO-WAY COUPLED PARTICLE LADEN FLOWS","authors":"M. Carbone, M. Iovieno","doi":"10.2495/AFM180241","DOIUrl":"https://doi.org/10.2495/AFM180241","url":null,"abstract":"We present the application of the Nonuniform Fast Fourier Transform (NUFFT) to the pseudo-spectral Eulerian–Lagrangian direct numerical simulation of particle-laden flows. In the two-way coupling regime, when the particle feedback on the flow is taken into account, a spectral method requires not only the interpolation of the flow fields at particle positions, but also the Fourier representation of the particle back-reaction on the flow fields on a regular grid. Even though the direct B-spline interpolation is a well-established tool, to the best of our knowledge the reverse projection scheme has never been used, replaced by less accurate linear reverse interpolation or Gaussian regularization. We propose to compute the particle momentum and temperature feedback on the flow by means of the forward NUFFT, while the backward NUFFT is used to perform the B-spline interpolation. Since the backward and forward transformations are symmetric and the (non local) convolution computed in physical space is removed in Fourier space, this procedure satisfies all constraints for a consistent interpolation scheme, and allows an efficient implementation of high-order interpolations. The resulting method is applied to the direct numerical simulation of a forced and isotropic turbulent flow with different particle Stokes numbers in the two-way coupling regime. A marked multifractal scaling is observed in the particle statistics, which implies that the feedback from the particles on the fields is far from being analytic and therefore only high-order methods, like the one here proposed, can provide an accurate representation.","PeriodicalId":261351,"journal":{"name":"Advances in Fluid Mechanics XII","volume":"54 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-07-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"123094856","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
F. B. Rajeb, M. A. Rahman, Yan Zhang, S. Imtiaz, A. Aborig, Mohamed Odan
In the present study, pipe flows are used to investigate the behavior flow of water–CO2 mixtures at different pressures and temperatures. The flow rate and pressure of water and CO2 are changed by using a pump placed ahead of the mixing point. Pressure and temperature levels are recorded by pressure sensors and thermocouples affixed at points along the pipe loop. The flow regimes of two-phase water– CO2 flow is visualized through transparent tubes using a high-speed camera. After several experiments, it was found that the mean pressure drop along the tube for a water–CO2 system flow is about 4 kPa/m for water flow rates between 0.4 and 0.7 L/S and CO2 flow rates between 2.5 and 11 L/S. The maximum inlet pressure for water is 400 kPa and for CO2 is 3000 kPa. In this experiment, the phase fraction of water is approximately 0.5–0.15 and the phase fraction of CO2 is around 0.85–0.95. The investigated flow regime under these flow conditions is often intermittent.
{"title":"PRESSURE LOSS OF WATER–CO2 TWO-PHASE FLOW UNDER DIFFERENT OPERATING CONDITIONS","authors":"F. B. Rajeb, M. A. Rahman, Yan Zhang, S. Imtiaz, A. Aborig, Mohamed Odan","doi":"10.2495/AFM180271","DOIUrl":"https://doi.org/10.2495/AFM180271","url":null,"abstract":"In the present study, pipe flows are used to investigate the behavior flow of water–CO2 mixtures at different pressures and temperatures. The flow rate and pressure of water and CO2 are changed by using a pump placed ahead of the mixing point. Pressure and temperature levels are recorded by pressure sensors and thermocouples affixed at points along the pipe loop. The flow regimes of two-phase water– CO2 flow is visualized through transparent tubes using a high-speed camera. After several experiments, it was found that the mean pressure drop along the tube for a water–CO2 system flow is about 4 kPa/m for water flow rates between 0.4 and 0.7 L/S and CO2 flow rates between 2.5 and 11 L/S. The maximum inlet pressure for water is 400 kPa and for CO2 is 3000 kPa. In this experiment, the phase fraction of water is approximately 0.5–0.15 and the phase fraction of CO2 is around 0.85–0.95. The investigated flow regime under these flow conditions is often intermittent.","PeriodicalId":261351,"journal":{"name":"Advances in Fluid Mechanics XII","volume":"27 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-07-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"114674425","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Flow structures in the wake of a square cylinder inclined with angles of = 0, 15, 30 and 45 undergoing forced oscillation are investigated experimentally using particle image velocimetry (PIV) at Keulegan–Carpenter (KC) numbers in the range of 5–30 to examine the performance of the Independent Principle (IP). For KC < 6, there is no vortex shedding from the cylinder for all angles and as a result, the IP is valid. For KC 820, IP does not work satisfactorily because at large inclination angles, the shear layers are stretched and reattach to the upper and lower sides of the cylinder body for most of the time within one oscillating cycle. When KC is increased further to 25, the phenomenon of shear layer attachment when the cylinder is at the neutral position, as well as the significant shedding at the end of each half cycle, indicate a similar flow field for both vertical and inclined cylinders. The present investigation indicates that the IP is valid when KC 6 and KC 20 as it is analogous to a steady current.
{"title":"EXPERIMENTAL INVESTIGATION OF FLOW FIELD AROUND AN INCLINED SQUARE CYLINDER UNDER FORCED OSCILLATION","authors":"T. Zhou, X. Lou, Yucen Lu","doi":"10.2495/AFM180061","DOIUrl":"https://doi.org/10.2495/AFM180061","url":null,"abstract":"Flow structures in the wake of a square cylinder inclined with angles of = 0, 15, 30 and 45 undergoing forced oscillation are investigated experimentally using particle image velocimetry (PIV) at Keulegan–Carpenter (KC) numbers in the range of 5–30 to examine the performance of the Independent Principle (IP). For KC < 6, there is no vortex shedding from the cylinder for all angles and as a result, the IP is valid. For KC 820, IP does not work satisfactorily because at large inclination angles, the shear layers are stretched and reattach to the upper and lower sides of the cylinder body for most of the time within one oscillating cycle. When KC is increased further to 25, the phenomenon of shear layer attachment when the cylinder is at the neutral position, as well as the significant shedding at the end of each half cycle, indicate a similar flow field for both vertical and inclined cylinders. The present investigation indicates that the IP is valid when KC 6 and KC 20 as it is analogous to a steady current.","PeriodicalId":261351,"journal":{"name":"Advances in Fluid Mechanics XII","volume":"63 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-07-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"126749696","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Interfacial shape of stratified flow of two liquids in pipes may take a planar or curved shape depending on the physical properties of the fluids, wall-fluid wettability, the geometrical dimensions and the fluids hold-up. It is traditionally accepted that the interfacial curvature is present in capillary and small-scale systems where the surface tension effect is significant against gravity effects. However, it is possible that interfacial curvature is present in liquid–liquid systems with small density differences or in reduced gravity systems due to dominating surface phenomena. Two phase flow of oil (density = 788 kg/m3, viscosity = 1.6 mPa.s) and water (density = 997 kg/m3, viscosity = 1 mPa.s) in a horizontal pipe was investigated for stratified flows. The longitudinal view was recorded using high-speed video imaging, while the cross sectional view of the flow was captured via Electrical Capacitance Tomography (ECT). As a third method, the interfacial level at the mid-pipe was calculated by referring to a work reported in literature. In addition, the interfacial level and the curvature in stratified smooth flow (ST), were calculated using CFD simulations as well. The ECT images indicated a blurred interfacial margin where the interface was reconstructed with a considerable thickness. However, the interfacial level at the pipe wall shown by the cross sectional ECT images were comparable with that of the high-speed images and the CFD simulations. Nevertheless, a significant interfacial curvature was encountered in ECT images towards the mid-pipe, which is 4.3 times deeper than the calculated value. CFD results agreed well with the calculated interfacial level using constant curvature arc model. In ECT, the depth of the curvature at the mid pipe seemed to be far more than the reality due to the possible field distortion effects occurring when the electrical flux lines pass through the media of high permittivity contrast (oil–water). Therefore, it was found that ECT can predict the interfacial oil–water level at the walls with acceptable accuracy, while it over-predicts the interfacial curvature present in the mid-pipe region. It is important to note that the ECT electrodes have their highest sensitivity near the wall region.
{"title":"INTERFACE DETECTION OF OIL–WATER STRATIFIED FLOW","authors":"K. Perera, M. Amaratunga, R. W. Time","doi":"10.2495/AFM180081","DOIUrl":"https://doi.org/10.2495/AFM180081","url":null,"abstract":"Interfacial shape of stratified flow of two liquids in pipes may take a planar or curved shape depending on the physical properties of the fluids, wall-fluid wettability, the geometrical dimensions and the fluids hold-up. It is traditionally accepted that the interfacial curvature is present in capillary and small-scale systems where the surface tension effect is significant against gravity effects. However, it is possible that interfacial curvature is present in liquid–liquid systems with small density differences or in reduced gravity systems due to dominating surface phenomena. Two phase flow of oil (density = 788 kg/m3, viscosity = 1.6 mPa.s) and water (density = 997 kg/m3, viscosity = 1 mPa.s) in a horizontal pipe was investigated for stratified flows. The longitudinal view was recorded using high-speed video imaging, while the cross sectional view of the flow was captured via Electrical Capacitance Tomography (ECT). As a third method, the interfacial level at the mid-pipe was calculated by referring to a work reported in literature. In addition, the interfacial level and the curvature in stratified smooth flow (ST), were calculated using CFD simulations as well. The ECT images indicated a blurred interfacial margin where the interface was reconstructed with a considerable thickness. However, the interfacial level at the pipe wall shown by the cross sectional ECT images were comparable with that of the high-speed images and the CFD simulations. Nevertheless, a significant interfacial curvature was encountered in ECT images towards the mid-pipe, which is 4.3 times deeper than the calculated value. CFD results agreed well with the calculated interfacial level using constant curvature arc model. In ECT, the depth of the curvature at the mid pipe seemed to be far more than the reality due to the possible field distortion effects occurring when the electrical flux lines pass through the media of high permittivity contrast (oil–water). Therefore, it was found that ECT can predict the interfacial oil–water level at the walls with acceptable accuracy, while it over-predicts the interfacial curvature present in the mid-pipe region. It is important to note that the ECT electrodes have their highest sensitivity near the wall region.","PeriodicalId":261351,"journal":{"name":"Advances in Fluid Mechanics XII","volume":"58 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-07-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"126772209","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Maéva Mikart, D. Counilh, F. Gensdarmes, A. Chinnayya
Over the past decades, the needs to mitigate detonation effects have significantly increased. To deal with these issues, the French Nuclear Energy Agency has studied aqueous foam confinement. This solution has two advantages. Firstly, the presence of these two-phases medium leads to drastically attenuate the blast wave generated by the detonation of an explosive device. Secondly, the presence of the liquid phase slows down and ultimately captures the micrometric and potentially harmful particles dispersed by the explosion. This specific topic will be discussed in this paper.
{"title":"CAPTURE OF PARTICLES DISPERSED BY DETONATION USING AN AQUEOUS FOAM CONFINEMENT","authors":"Maéva Mikart, D. Counilh, F. Gensdarmes, A. Chinnayya","doi":"10.2495/AFM180091","DOIUrl":"https://doi.org/10.2495/AFM180091","url":null,"abstract":"Over the past decades, the needs to mitigate detonation effects have significantly increased. To deal with these issues, the French Nuclear Energy Agency has studied aqueous foam confinement. This solution has two advantages. Firstly, the presence of these two-phases medium leads to drastically attenuate the blast wave generated by the detonation of an explosive device. Secondly, the presence of the liquid phase slows down and ultimately captures the micrometric and potentially harmful particles dispersed by the explosion. This specific topic will be discussed in this paper.","PeriodicalId":261351,"journal":{"name":"Advances in Fluid Mechanics XII","volume":"6 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-07-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"130557129","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
In the process industry, vacuum-type dryers are becoming increasingly important. A special case of vacuum drying is lyophilization, where a solution, containing up to 90% of solvent (typically water), is dried under the conditions of very low temperatures and extremely low system pressures. As a container type, in which the solution is dried, a vial is frequently used. The intensity of drying is to a large extent controlled by the pressure conditions above the drying surface. The vial and the rubber stopper geometry present a significant pressure drop in the flow of sublimated solvent, but are experimentally difficult to determine. In order to produce realistic pressure conditions for the mass transfer computation, a CFD analysis of flow inside the vial-stopper channel is performed. The influence of imposing the no-slip and slip conditions on the solid surfaces on the pressure drop in the system is studied under the typical sublimation conditions. The effect of the increased partial pressure of the solvent on the sublimation rate is calculated by implementing the Maxwell–Stefan diffusion model.
{"title":"THE INFLUENCE OF A VIAL STOPPER ON FLOW AND MASS TRANSFER CONDITIONS INSIDE A VIAL","authors":"M. Hriberšek, M. Zadravec, Ziga Casar, J. Ravnik","doi":"10.2495/AFM180191","DOIUrl":"https://doi.org/10.2495/AFM180191","url":null,"abstract":"In the process industry, vacuum-type dryers are becoming increasingly important. A special case of vacuum drying is lyophilization, where a solution, containing up to 90% of solvent (typically water), is dried under the conditions of very low temperatures and extremely low system pressures. As a container type, in which the solution is dried, a vial is frequently used. The intensity of drying is to a large extent controlled by the pressure conditions above the drying surface. The vial and the rubber stopper geometry present a significant pressure drop in the flow of sublimated solvent, but are experimentally difficult to determine. In order to produce realistic pressure conditions for the mass transfer computation, a CFD analysis of flow inside the vial-stopper channel is performed. The influence of imposing the no-slip and slip conditions on the solid surfaces on the pressure drop in the system is studied under the typical sublimation conditions. The effect of the increased partial pressure of the solvent on the sublimation rate is calculated by implementing the Maxwell–Stefan diffusion model.","PeriodicalId":261351,"journal":{"name":"Advances in Fluid Mechanics XII","volume":"13 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-07-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"121194858","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Optical techniques have been applied for inspecting inside the primary containment vessels (PCV) in the decommissioning of the Fukushima Dai-ichi nuclear power plant. In this inspection, the following are required: determining fuel debris distribution and identifying location of leakage. Until this data, one of the inspections achieved great progress by capturing several images of fuel debris using a video camera but no information of the leak was unveiled due to non-clear water causing poor visibility of that camera. In order to identify the location of the leak, a new imaging method combining diverging wave (DW) and total focusing method (TFM), named DW-TFM was proposed aimed at echo (ultrasound)-particle image velocimetry (PIV) since an ultrasound can be used in opaque liquid and ultrasonic transducers are generally suited to high radiation levels. This imaging method uses an ultrasonic array sensor and emits a DW spreading in the distance from that sensor. The echo signal of tracer particles where the DW passed is captured by all the elements in the sensor at the same time and an echo image is then reconstructed from those signals using TFM algorithm. The imaging method is expected to obtain echo images covering a wide range in one transmission. Echo-PIV uses consecutive echo images captured at a certain interval to process them with PIV algorithm and obtain an averaged vector flow map (VFM). Summarizing the above, echo-PIV using the DW-TFM has the potential to visualize a wide range of flow behavior in real time and it allows the location of the leak to be found quickly. After investigating the imaging performance of the DW-PIV and developing a measurement system for the suggested echo-PIV, experimental measurement was conducted under a simple condition of water leaking from a tank in order to confirm its applicability. In this test, leaking position could be assumed from the measured VFM and it has good agreement with the actual leakage position. The achievability of the method for the leakage point detection is hereby presented.
{"title":"A STUDY ON 2-D VECTOR FLOW MAPPING BY ECHO-PIV WITH TOTAL FOCUSING METHOD","authors":"T. Kawachi, H. Takahashi, H. Kikura","doi":"10.2495/AFM180281","DOIUrl":"https://doi.org/10.2495/AFM180281","url":null,"abstract":"Optical techniques have been applied for inspecting inside the primary containment vessels (PCV) in the decommissioning of the Fukushima Dai-ichi nuclear power plant. In this inspection, the following are required: determining fuel debris distribution and identifying location of leakage. Until this data, one of the inspections achieved great progress by capturing several images of fuel debris using a video camera but no information of the leak was unveiled due to non-clear water causing poor visibility of that camera. In order to identify the location of the leak, a new imaging method combining diverging wave (DW) and total focusing method (TFM), named DW-TFM was proposed aimed at echo (ultrasound)-particle image velocimetry (PIV) since an ultrasound can be used in opaque liquid and ultrasonic transducers are generally suited to high radiation levels. This imaging method uses an ultrasonic array sensor and emits a DW spreading in the distance from that sensor. The echo signal of tracer particles where the DW passed is captured by all the elements in the sensor at the same time and an echo image is then reconstructed from those signals using TFM algorithm. The imaging method is expected to obtain echo images covering a wide range in one transmission. Echo-PIV uses consecutive echo images captured at a certain interval to process them with PIV algorithm and obtain an averaged vector flow map (VFM). Summarizing the above, echo-PIV using the DW-TFM has the potential to visualize a wide range of flow behavior in real time and it allows the location of the leak to be found quickly. After investigating the imaging performance of the DW-PIV and developing a measurement system for the suggested echo-PIV, experimental measurement was conducted under a simple condition of water leaking from a tank in order to confirm its applicability. In this test, leaking position could be assumed from the measured VFM and it has good agreement with the actual leakage position. The achievability of the method for the leakage point detection is hereby presented.","PeriodicalId":261351,"journal":{"name":"Advances in Fluid Mechanics XII","volume":"10 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-07-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"126370664","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
A mud pump is a reciprocating liner (piston/plunger) pump designed to circulate drilling fluid under high pressure down the drill string and back up the annulus. A mud pump is an important part of the equipment used for oil well drilling. The automatic valves of the fluid-end produce the pumping effect. The valves consist of a movable body and a reaction spring. The spring is designed in order to avoid leakage and prevent contact between the valve itself and the retaining cage. Its proper sizing depends on the operating conditions as well as the properties of the fluid. The valve seat geometry significantly contributes to ensure the tightness of the fluid-end. An aspect that should be carefully considered during the design of new geometries is the phenomenon of cavitation. Cavitation consists in the development of vapour cavities in the liquid phase. Inside the cavities the pressure is relatively low. When subjected to higher pressure, the voids implode and generate an intense shock wave that promotes the wear of the components (i.e. valve, valve seat, etc.). A deep understanding of the fluid behaviour is crucial for an effective design. Transient CFD simulations of the valve opening have been performed using a nonNewtonian fluid model able to describe the drilling muds. After a deep literature review, the Herschel– Bulkley model was selected as the most suitable for emulating the drilling mud. With the above mentioned approach, the reaction spring and valve seat were designed properly to avoid premature wear phenomena.
{"title":"ANALYSIS OF AN AUTOMATIC VALVE GEOMETRY FOR CONCRETE AND DRILLING MUD PUMPS TO AVOID CAVITATION: NON-NEWTONIAN CFD MODELLING","authors":"F. Concli, C. Gorla","doi":"10.2495/AFM180211","DOIUrl":"https://doi.org/10.2495/AFM180211","url":null,"abstract":"A mud pump is a reciprocating liner (piston/plunger) pump designed to circulate drilling fluid under high pressure down the drill string and back up the annulus. A mud pump is an important part of the equipment used for oil well drilling. The automatic valves of the fluid-end produce the pumping effect. The valves consist of a movable body and a reaction spring. The spring is designed in order to avoid leakage and prevent contact between the valve itself and the retaining cage. Its proper sizing depends on the operating conditions as well as the properties of the fluid. The valve seat geometry significantly contributes to ensure the tightness of the fluid-end. An aspect that should be carefully considered during the design of new geometries is the phenomenon of cavitation. Cavitation consists in the development of vapour cavities in the liquid phase. Inside the cavities the pressure is relatively low. When subjected to higher pressure, the voids implode and generate an intense shock wave that promotes the wear of the components (i.e. valve, valve seat, etc.). A deep understanding of the fluid behaviour is crucial for an effective design. Transient CFD simulations of the valve opening have been performed using a nonNewtonian fluid model able to describe the drilling muds. After a deep literature review, the Herschel– Bulkley model was selected as the most suitable for emulating the drilling mud. With the above mentioned approach, the reaction spring and valve seat were designed properly to avoid premature wear phenomena.","PeriodicalId":261351,"journal":{"name":"Advances in Fluid Mechanics XII","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-07-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"128012992","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
M. N. F. Rab, Muhammad Junaid Alam, Ahson Akhlaque, M. Mahrukh
The purpose of this study is to analyse various high-lift low-Reynolds-number airfoils using the XFOIL airfoil analysis code in the isolated flow field and to select the optimum airfoil to suit motorsports applications. The airfoil is selected after comparing the stall behavior, transition location, pressure recovery, pressure distribution and boundary-layer characteristics of various airfoils. The prime consideration while selecting an airfoil is the highest Cl while achieving the sustainable performance over a range of Reynolds numbers encountered on the race track. An increase in Cl is always accompanied by an increase in Cd; however, this must be compromised since the main goal is to increase the aerodynamic grip. It is always desirable to increase the downforce in Formula One /Formula Student to gain a reduction in lap time. This paper establishes the criteria for the selection of high-lift low-Reynolds-number airfoils, while considering the various parameters that affect the performance of airfoils.
{"title":"COMPARATIVE ANALYSIS OF HIGH-LIFT AIRFOILS FOR MOTORSPORTS APPLICATIONS","authors":"M. N. F. Rab, Muhammad Junaid Alam, Ahson Akhlaque, M. Mahrukh","doi":"10.2495/AFM180171","DOIUrl":"https://doi.org/10.2495/AFM180171","url":null,"abstract":"The purpose of this study is to analyse various high-lift low-Reynolds-number airfoils using the XFOIL airfoil analysis code in the isolated flow field and to select the optimum airfoil to suit motorsports applications. The airfoil is selected after comparing the stall behavior, transition location, pressure recovery, pressure distribution and boundary-layer characteristics of various airfoils. The prime consideration while selecting an airfoil is the highest Cl while achieving the sustainable performance over a range of Reynolds numbers encountered on the race track. An increase in Cl is always accompanied by an increase in Cd; however, this must be compromised since the main goal is to increase the aerodynamic grip. It is always desirable to increase the downforce in Formula One /Formula Student to gain a reduction in lap time. This paper establishes the criteria for the selection of high-lift low-Reynolds-number airfoils, while considering the various parameters that affect the performance of airfoils.","PeriodicalId":261351,"journal":{"name":"Advances in Fluid Mechanics XII","volume":"117 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-07-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"114905865","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Many industrial devices found in the oil and gas industries are designed using empirical correlations, such as gas–liquid vertical separators. However, the physics involved in these devices are quite complex including multiphase flows and internal devices that are not considered in the empirical approach. Therefore, important discrepancies are found in industrial fields. This research conducts a numerical study using Computational Fluid Dynamics (CFD) to assess the different empirical models used in such designs. A short review of the different models is presented and compared and computational experiments are used to evaluate the parameters of importance of these devices. In addition, statistical models are implemented to evaluate the influence of operational parameters, properties of fluids and geometric variables to the efficiency of the separator and pressure drop. To this end, a surrogate model is developed using Kriging interpolation that allows evaluation of the different combination of parameters without running each design using CFD. Preliminary results demonstrate that the standard accepted as general reference ANSI/ANSI/API-12J provides the lowest efficiency and the higher pressure drop, albeit small, compared to the other methods.
{"title":"NUMERICAL INVESTIGATION OF VERTICAL GAS–LIQUID SEPARATORS USING COMPUTATIONAL FLUID DYNAMICS AND STATISTICAL TECHNIQUES","authors":"J. Mendez, A. Efendioglu, J. Guevara","doi":"10.2495/AFM180111","DOIUrl":"https://doi.org/10.2495/AFM180111","url":null,"abstract":"Many industrial devices found in the oil and gas industries are designed using empirical correlations, such as gas–liquid vertical separators. However, the physics involved in these devices are quite complex including multiphase flows and internal devices that are not considered in the empirical approach. Therefore, important discrepancies are found in industrial fields. This research conducts a numerical study using Computational Fluid Dynamics (CFD) to assess the different empirical models used in such designs. A short review of the different models is presented and compared and computational experiments are used to evaluate the parameters of importance of these devices. In addition, statistical models are implemented to evaluate the influence of operational parameters, properties of fluids and geometric variables to the efficiency of the separator and pressure drop. To this end, a surrogate model is developed using Kriging interpolation that allows evaluation of the different combination of parameters without running each design using CFD. Preliminary results demonstrate that the standard accepted as general reference ANSI/ANSI/API-12J provides the lowest efficiency and the higher pressure drop, albeit small, compared to the other methods.","PeriodicalId":261351,"journal":{"name":"Advances in Fluid Mechanics XII","volume":"27 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-07-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"128404010","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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