Study of Gas/Liquid Behavior Within an Aeroengine Bearing Chamber

2013 ◽  
Vol 135 (5) ◽  
Author(s):  
Budi Chandra ◽  
Kathy Simmons ◽  
Stephen Pickering ◽  
Steven H. Collicott ◽  
Nikolas Wiedemann
Keyword(s):  
Film Thickness ◽  
High Speed ◽  
Flow Behavior ◽  
Ambient Pressure ◽  
Current Model ◽  
Test Chamber ◽  
Experimental Program ◽  
Working Fluid ◽  
Rotating Shaft ◽  
Significant Difference

Aeroengine bearing chambers typically contain bearings, seals, shafts and static parts. Oil is introduced for lubrication and cooling and this creates a two phase flow environment that may contain droplets, mist, film, ligaments, froth or foam and liquid pools. Some regions of the chamber contain a highly rotating air flow such that there are zones where the flow is gravity dominated and zones where it is rotation dominated. The University of Nottingham Technology Centre in Gas Turbine Transmission Systems, is conducting an ongoing experimental program investigating liquid and gas flow behavior in a relevant highly rotating environment. Previously reported work by the UTC has investigated film thickness and residence volume within a simplified chamber consisting of outer cylindrical chamber, inner rotating shaft and cuboid off-take geometry (termed the generic deep sump). Recently, a more aeroengine relevant bearing chamber offtake geometry has been studied. This geometry is similar to one investigated at Purdue University and consists of a “sub-sump” region approached by curved surfaces linked to the bearing chamber. The test chamber consists of an outer, stationary cylinder with an inner rotating shaft. The rig runs at ambient pressure and the working fluid (water) is introduced either via a film generator on the chamber wall or through holes in the shaft. In addition to visual data (high speed and normal video), liquid residence volume within the chamber and film thickness were the two numerical comparators chosen. Data was obtained for a number of liquid supply rates, scavenge ratios and shaft rotation speeds. The data from the current model is compared to that from the earlier studies. The data shows that in contrast to the previously reported generic deep sump study, the residence volume of the curved wall deep sump (CWDS) designs is far less sensitive to shaft speed, liquid supply rate and scavenge ratio. The method of liquid supply only makes a significant difference at the lowest scavenge ratios. Residence volume data for the Nottingham CWDS is comparable, when appropriately scaled, to that for the Purdue design. The film thickness data shows that at the lower shaft speeds investigated the flow is gravity dominated whereas at higher shaft speeds shear dominates.

Study of Gas/Liquid Behaviour Within an Aeroengine Bearing Chamber

2012 ◽  
Author(s):  
Budi Chandra ◽  
Kathy Simmons ◽  
Stephen Pickering ◽  
Steven H. Collicott ◽  
Nikolas Wiedemann
Keyword(s):  
Film Thickness ◽  
High Speed ◽  
Flow Behavior ◽  
Ambient Pressure ◽  
Current Model ◽  
Test Chamber ◽  
Experimental Program ◽  
Working Fluid ◽  
Rotating Shaft ◽  
Significant Difference

Aeroengine bearing chambers typically contain bearings, seals, shafts and static parts. Oil is introduced for lubrication and cooling and this creates a two phase flow environment that may contain droplets, mist, film, ligaments, froth or foam and liquid pools. Some regions of the chamber contain a highly rotating air flow such that there are zones where the flow is gravity dominated and zones where it is rotation dominated. The University of Nottingham Technology Centre in Gas Turbine Transmission Systems, is conducting an ongoing experimental program investigating liquid and gas flow behavior in a relevant highly rotating environment. Previously reported work by Chandra et al [1, 2] has investigated film thickness and residence volume within a simplified chamber consisting of outer cylindrical chamber, inner rotating shaft and cuboid off-take geometry (termed the generic deep sump). Recently a more aeroengine relevant bearing chamber offtake geometry has been studied. This geometry is similar to one investigated by Chandra [3] at Purdue University and consists of a “sub-sump” region approached by curved surfaces linked to the bearing chamber. The test chamber consists of an outer, stationary cylinder with an inner rotating shaft. The rig runs at ambient pressure and the working fluid (water) is introduced either via a film generator on the chamber wall or through holes in the shaft. In addition to visual data (high speed and normal video), liquid residence volume within the chamber and film thickness were the two numerical comparators chosen. Data was obtained for a number of liquid supply rates, scavenge ratios and shaft rotation speeds. The data from the current model is compared to that from the earlier studies [1, 2, & 3]. The data shows that in contrast to the previously reported generic deep sump study, the residence volume of the curved wall deep sump (CWDS) designs is far less sensitive to shaft speed, liquid supply rate and scavenge ratio. The method of liquid supply only makes a significant difference at the lowest scavenge ratios. Residence volume data for the Nottingham CWDS is comparable, when appropriately scaled, to that for the Purdue design. The film thickness data shows that at the lower shaft speeds investigated the flow is gravity dominated whereas at higher shaft speeds shear dominates.

The Effect of Surface Wettability on Viscous Film Deposition

2009 ◽  
Author(s):  
Alexandru Herescu ◽  
Jeffrey S. Allen
Keyword(s):  
Contact Angle ◽  
Film Thickness ◽  
Capillary Number ◽  
High Speed ◽  
Glass Tube ◽  
Contact Angles ◽  
Film Deposition ◽  
Surface Wettability ◽  
Working Fluid ◽  
Uniqueness Of The Solution

The viscous deposition of a liquid film on the inside of a capillary has been experimentally investigated with a focus on the relationship between the film thickness and surface wettability. With distilled water as a working fluid tests were run in a 622 microns diameter glass tube with contact angles of 30° and 105°, respectively. In the first set of experiments the tube was uncoated while in the second set a fluoropolymer coating was applied to increase the contact angle. A film thickness dependence with the contact angle θ (surface wettability) as well as the Capillary number in the form hR ∼ Ca2/3/cosθ is inferred from scaling arguments. For partial wetting it may explain the existence of a thicker film for nonzero contact angle. It was further found that the non-wetting case of 105° contact angle deviates significantly from the existing theories, the film thickness presenting a weak dependence with the Capillary number. This deviation as well as the apparent non-uniqueness of the solution is thought to be caused by the film instability (rupture) observed during the tests. The thickness of the deposited film as a function of the Capillary number was estimated from the liquid mass exiting the capillary and the gas-liquid interface (meniscus) velocity, and compared to Bretherton’s data and a correlation proposed by Quere. The film thickness measurements as well as the meniscus velocity were determined with the aid of a Photron high speed camera with 10000 frames per second sampling capability coupled with a Nikon TE-2000 inverted microscope and a Precisa electronic balance.

Experimental and Numerical Simulation on Hydraulic Behavior of Molten Flow in the Lower Part in Reactor Core

2016 ◽  
Author(s):  
Kota Matsuura ◽  
Hideaki Monji ◽  
Susumu Yamashita ◽  
Hiroyuki Yoshida
Keyword(s):  
Numerical Simulation ◽  
Liquid Film ◽  
High Speed ◽  
Nuclear Power ◽  
Power Plants ◽  
Flow Behavior ◽  
Reactor Core ◽  
Video Camera ◽  
Working Fluid ◽  
Simulation Code

In the decommissioning work of nuclear power plants, it is important to grasp the sedimentation place of molten materials. However, the technique to grasp exactly sedimentation place is not established now. Therefore, the detailed and phenomenological numerical simulation code named JUPITER for predicting the molten core behavior is developed. In the study, visualization experiment and numerical simulation were performed to validate the applicability of the JUPITER to the hydraulic relocation behavior in core internals. The test section used in this experiment simulated the structure of the core internals, such as a control rod and a fuel support piece, simply. The working fluid is water under the atmospheric pressure. The experiment uses a high-speed video camera to visualize the flow behavior. The behavior and the speed of the liquid film in a narrow flow channel is obtained. For the numerical analysis carried out prior to the experiment, the behavior of flow down liquid was shown. The typical behavior was also observed that the tip of a liquid film flowing down splits into.

Helium-Air Exchange Flow Rate Measurement Through a Small Opening

2007 ◽  
Author(s):  
Motoo Fumizawa ◽  
Hidenori Horiuchi
Keyword(s):  
Flow Rate ◽  
High Speed ◽  
Flow Behavior ◽  
Test Chamber ◽  
Digital Data ◽  
Cover Plate ◽  
Vacuum Vessel ◽  
Exchange Flow ◽  
Counter Flow ◽  
Mass Increment

Buoyancy-driven counter flows of helium-air were investigated through horizontal and inclined small openings. Counter flows may occur following a window opening as ventilation, fire in the room as well as a pipe rupture accident in a high temperature gas-cooled nuclear reactor [1]. The counter flows also occur following the fusion reactor accident of LOVA that takes place through the breaches of vacuum vessel penetration duct [2]. The experiment has carried out by a test chamber filled with helium and flow was visualized by the smoke wire method. The flow behavior has recorded by a high-speed camera with a computer system. The image of the flow was transferred to the digital data, thus the flow velocity was measured by PTV software. The mass fraction in the test chamber was measured by electronic balance. The detected data was arranged by the densimetric Floude number of the counter flow rate that derived from the dimensional analysis. The method of mass increment was developed and applied to measure the counter flow rate. By removing the cover plate placed on the top of the opening, the counter flow initiated. Air enters the test chamber and the mass of the gas mixture in the test chamber increased. The volumetric counter flow rate was evaluated from the mass increment data. In the case of inclination openings, the results of both methods were compared. The inclination angle for maximum densimetric Floude number decreased with increasing length-to-diameter ratio of the opening. For a horizontal opening, the results from the method of mass increment agreed with those obtained by other authors for a water-brine system.

Experimental and Numerical Investigation of Near-Nozzle Flow Behaviour Under Flash Boiling Conditions

2017 ◽  
Author(s):  
Bo Wang ◽  
Xinyu Zhang ◽  
Yuying Yan ◽  
Jean-Paul Kone
Keyword(s):  
High Speed ◽  
Flow Behavior ◽  
Near Field ◽  
Air Entrainment ◽  
Nozzle Flow ◽  
Ambient Conditions ◽  
Fuel Temperature ◽  
Long Distance ◽  
Significant Difference ◽  
Flash Boiling

Precise control of the spray behavior is key to fully realize the potential benefits of modern GDI engines. Flash boiling is known to alert the spray behavior significantly; and thus, a complete understanding of its mechanism is essential. In this work, a study of the effect of the fuel properties on the near-nozzle flow characteristics of a single-hole GDI injector under the flash boiling conditions is presented. The performance of hexane and a typical gasoline surrogate iso-octane has been studied both experimentally and numerically. Fuel temperature varied from 20 and 100 °C with ambient pressures of 20, 50 and 100 kPa. For the experiment, microscopic imaging was conducted with a high-speed camera coupled with a long-distance microscope; and a convex lens was used to provide enough illumination to the interested area. The numerical studies were performed at the maximum needle lift using OpenFOAM, an open-source Computational Fluid Dynamics (CFD) code. Phase change was captured with the Homogeneous Relaxation Model (HRM); and turbulence was modeled using RNG k–ε model. The results have shown that while the near-field flow behavior of hexane and isooctane was similar under ambient conditions, a significant difference was observed between the two under the flash boiling conditions. The onset and development of flash boiling of isooctane was retarded compared to hexane due to its much lower vapor pressure. Spray contraction has been observed in the down-stream due to fuel vaporization and air entrainment. The CFD results were shown to agree well with the experimental data.

scholarly journals Experimental Investigation of Annular Flow Behaviour in Horizontal Pipe

2021 ◽  
Vol 13 (6) ◽  
Author(s):  
Osokogwu Osokogwu ◽  
◽  
Uche Uche ◽  
Keyword(s):  
Film Thickness ◽  
Liquid Film ◽  
Slug Flow ◽  
High Speed ◽  
Annular Flow ◽  
Flow Behavior ◽  
Liquid Film Thickness ◽  
Experimental Investigations ◽  
Internal Diameter ◽  
Horizontal Pipe

The experimental investigations of annular flow were conducted in horizontal pipe using water/air in a 0.0504m internal diameter pipe loop with a total length of 28.68m. To understand annular flow behaviors, conductivity ring sensors, conductance probe sensors and Olympia high speed digital camera were used. In all the experiments, emphasis were on annular flow behavior, phase distribution and liquid film thickness. Liquid film thickness was observed to be thicker mostly when the superficial gas velocities were within 8.2699 m/s to 12.0675 m/s. Above the aforementioned superficial gas velocities, the flow became uniformly distributed on the walls of the internal pipe diameter hence reducing the thicker liquid film at the bottom with gas core at the center of the pipe. More so, annular-slug flow was discovered in the investigation. At superficial liquid velocity of 0.0505 m/s-0.1355 m/s on superficial gas velocities of 8.2699 m/s – 12.0675 m/s, annular-slug flow was prominent. Also discovered was at superficial liquid velocities of 0.0903 m/s - 0.1355 m/s with respect to superficial gas velocities of 13.1692 m/s – 23.4575 m/s, the pipe walls are fully covered with liquid film at very high speed at the entire walls (upper walls and bottom). Also discovered in this experiment is the wavy flow of the upper walls. The liquid film thickness that flows at the upper pipe walls, creeps in a wavy flow. Therefore, the entire flow behavior in an annular flow could be grouped into; wavy-flow at the upper walls, annular-slug flow and thicker liquid film at the bottom with gas core at the center.

Visualization and Numerical Simulation of Exchange Flow in Density Different Gases

2012 ◽  
Author(s):  
Motoo Fumizawa ◽  
Shuhei Ohkawa ◽  
Isaku Buma ◽  
Suguru Tanaka
Keyword(s):  
Numerical Simulation ◽  
High Speed ◽  
Flow Behavior ◽  
Test Chamber ◽  
Particle Method ◽  
Digital Data ◽  
Exchange Flow ◽  
Exchange Flows ◽  
Wire Method ◽  
Moving Particle

Buoyancy-driven exchange flows of helium-air through inclined a narrow tube was investigated. Exchange flows may occur following the opening of a window for ventilation, as well as when a pipe ruptures in a high temperature gas-cooled reactor. The experiment in this paper was carried out in a test chamber filled with helium and the flow was visualized using the smoke wire method. A high-speed camera recorded the flow behavior. The image of the flow was transferred to digital data, and the slow flow velocity, i.e. micro flow rate was measured by PIV software. Numerical simulation was carried out by the code of moving particle method with Lagrange method.

Performance of Two-Phase Microchannels at Sub-Atmospheric Pressure

2006 ◽  
Author(s):  
Tao Tong ◽  
Shankar Devasenathipathy ◽  
Je-Young Chang ◽  
John Dirner ◽  
Suzana Prstic ◽  
...  
Keyword(s):  
Pressure Drop ◽  
Atmospheric Pressure ◽  
High Speed ◽  
Flow Boiling ◽  
Ambient Pressure ◽  
Saturation Temperature ◽  
Heat Removal ◽  
Working Fluid ◽  
Cold Plate ◽  
Two Phase

Two-phase microchannel system is a promising technology to achieve enhanced heat removal and more effective cooling of hotspots. The excellent thermodynamic properties of water make it a prime candidate as the working fluid in two-phase microchannel systems. While typical integrated circuit components require die temperature to remain below 95 °C, most of the earlier microchannel flow boiling studies were conducted at or above ambient pressure, where the saturation temperature of water is equal to or higher than 100 °C. In this paper, we tested flow boiling at sub-atmospheric pressure such that the saturation temperature of water can be significantly reduced below 95 °C. We study the pressure drop and heat transfer characteristics of our two-phase cold plate configuration, under uniform and hotspot (non-uniform) heating conditions at sub-atmospheric system pressures. A cold plate with 61 μm wide and 272 μm deep microchannels was tested at two systems pressures of 35 and 46 kPa and at two mass flow rates of 67 and 107 kg/m2-s. High-speed flow imaging was used for identifying flow patterns in the microchannels with the above test conditions. Pressure drop data were compared with the available semi-empirical correlations and the annular flow model. An explanation was proposed for the mismatch between the models under current microchannel configuration.

scholarly journals Visualization and measurement of turbulent flow inside a Submerged Entry Nozzle and off the ports

2021 ◽  
Vol 67 (4 Jul-Aug) ◽  
pp. 040601
Author(s):  
C. A. Real-Ramirez ◽  
I. Carvajal-Mariscal ◽  
J. R. Miranda-Tello ◽  
J. Gonzalez-Trejo ◽  
R. Gabbasov ◽  
...  
Keyword(s):  
Turbulent Flow ◽  
High Speed ◽  
Flow Behavior ◽  
Submerged Entry Nozzle ◽  
Internal Flow ◽  
Casting Process ◽  
Working Fluid ◽  
Particle Hydrodynamics ◽  
Transparent Cell ◽  
Particle Imaging

This work describes a visualization technique that allows to register and analyze flow inside a Submerged Entry Nozzle (SEN) model. The internal flow has a swirling pattern that produces characteristic flow conditions that can be used in efficiently supplying liquid steel from the tundish to the mold in the continuous casting process. The visualization method is a first step in analyzing the characteristics of the internal flow and hence in designing new SENs. A LED light source is employed to illuminate the SEN which reduces the reflections in the images. To enhance visualizations and measurements, a transparent cell consisting of a cubic volume with reduced dimensions was used to capture images from the high-speed camera and to record the flow pattern within the SEN. The SEN model consists of a vertical, constant diameter tube with two rounded exit ports located at the bottom with a downward angle of 15° each. The working fluid is water and reaches Re=10,000 within the cell. We also use the laser illuminated Particle Imaging Velocimetry (PIV) to calculate the velocity of fluid within the SEN and close to the exit ports. We confirm previously reported formation of three vortexes that interact with each other altering the swirl motion of the exit flow. Experimental results were compared with numerical simulations. The comparisons contribute to the validation of findings of Computational Fluid Dynamics (CFD) and Smoothed-Particle Hydrodynamics (SPH) results. Qualitative and quantitative similarities were found. Both physical and numerical results display a high turbulent flow behavior at the lower zone of the SEN. Experimental and numerical methods may be used together as a development method to measure and evaluate the characteristics of the flow behavior inside and outside the SEN model in order to design a better SEN to increase the quality of the steel slab.

Liquid and Gas Flow Behaviour in Highly Rotating Environment

2011 ◽  
Author(s):  
Budi Chandra ◽  
Kathy Simmons ◽  
Stephen Pickering ◽  
Marc Tittel
Keyword(s):  
Film Thickness ◽  
Liquid Film ◽  
Gas Flow ◽  
Flow Behavior ◽  
Thin Liquid Film ◽  
Air Flow ◽  
Chamber Wall ◽  
Experimental Program ◽  
Cfd Validation ◽  
Data Set

In a typical aero engine bearing chamber, oil is introduced to lubricate and cool the bearings as well as the bearing chamber wall. The flow of the oil in the bearing chamber is very complex due to the presence of various forces: gravity, windage, capillary, etc. These pose a great challenge for designers, in particular on how to effectively and efficiently scavenge the hot oil out of the bearing chamber. The University of Nottingham Technology Centre in Gas Turbine Transmission Systems is conducting an ongoing experimental program on liquid and gas flow behavior in the highly rotating environment typically found in a bearing chamber. This paper presents results from a study of the thin film on the wall of a generic bearing chamber consisting of an inner rotating shaft and outer stationary cylindrical wall. Thin liquid film behavior in a cylindrical chamber, subject to only gravity or together with the presence of shearing air flow is of interest in many industrial applications and processes. Measurements of film thickness were taken at various axial and angular locations, at various representative inlet flow rates, scavenge ratios and shaft rotational speeds. The experimental data provides insight on the behavior of thin liquid film as it travels down the inner chamber wall subject to both gravity and shearing air flow and provides a data set eminently suitable for CFD validation. The film thickness measurements are discussed in relation to previously published chamber residence volume data [1].

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