A Numerical Model for Oil Film Flow in an Aeroengine Bearing Chamber and Comparison to Experimental Data

2004 ◽  
Vol 128 (1) ◽  
pp. 111-117 ◽  
Author(s):  
Mark Farrall ◽  
Kathy Simmons ◽  
Stephen Hibberd ◽  
Philippe Gorse
Keyword(s):  
Experimental Data ◽  
Boundary Conditions ◽  
Film Flow ◽  
Roller Bearing ◽  
Numerical Approach ◽  
Interfacial Shear ◽  
Oil Droplets ◽  
Two Phase ◽  
Oil Film ◽  
The Impact

The work presented forms part of an ongoing investigation, focusing on modeling the motion of a wall oil film present in a bearing chamber and comparison to existing experimental data. The film is generated through the impingement of oil droplets shed from a roller bearing. Momentum resulting from the impact of oil droplets, interfacial shear from the airflow, and gravity cause the film to migrate around the chamber. Oil and air exit the chamber at scavenge and vent ports. A previously reported numerical approach to the simulation of steady-state two-phase flow in a bearing chamber, which includes in-house submodels for droplet-film interaction and oil film motion, has been extended. This paper includes the addition of boundary conditions for the vent and scavenge together with a comparison to experimental results obtained from ITS, University of Karlsruhe. The solution is found to be sensitive to the choice of boundary conditions applied to the vent and scavenge.

A Numerical Model for Oil Film Flow in an Aero-Engine Bearing Chamber and Comparison With Experimental Data

2004 ◽  
Author(s):  
Mark Farrall ◽  
Kathy Simmons ◽  
Stephen Hibberd ◽  
Philippe Gorse
Keyword(s):  
Experimental Data ◽  
Boundary Conditions ◽  
Roller Bearing ◽  
Numerical Approach ◽  
Oil Droplets ◽  
Two Phase ◽  
Oil Film ◽  
Aero Engine ◽  
The Impact ◽  
Engine Bearing

The work presented forms part of an on-going investigation, focusing on modelling the motion of a wall oil film present in a bearing chamber and comparison with existing experimental data. The film is generated through the impingement of oil droplets shed from a roller bearing. Momentum resulting from the impact of oil droplets, interfacial shear from the airflow, and gravity cause the film to migrate around the chamber. Oil and air exit the chamber at scavenge and vent ports. A previously reported numerical approach to the simulation of steady-state two-phase flow in a bearing chamber, that includes in-house sub-models for droplet-film interaction and oil film motion, has been extended. This paper includes the addition of boundary conditions for the vent and scavenge together with a comparison to experimental results obtained from ITS, University of Karlsruhe. The solution is found to be sensitive to the choice of boundary conditions applied to the vent and scavenge.

Paper 30: A Theory for the Prediction of Local Phase Velocity, Static Pressure and Amount Condensed for Condensing Annular Flow in Tubes

1969 ◽  
Vol 184 (7) ◽  
pp. 64-69
Author(s):  
A. Porteous
Keyword(s):  
Experimental Data ◽  
Phase Velocity ◽  
Annular Flow ◽  
Static Pressure ◽  
Interfacial Shear ◽  
Phase Flow ◽  
Local Phase ◽  
Two Phase ◽  
Condensate Film ◽  
Comparison With Experimental Data

This paper presents a theory for condensing fluid flow in pipes. The theory incorporates the Reynolds flux concepts, advanced by Silver and Silver and Wallis, to account for the modification of interfacial shear when a phase change occurs across an interface. The basic theory is applicable to any fluid condensing in the annular two-phase flow régime and enables good predictions to be made for the local values of phase velocity, static pressure, and amount condensed. A comparison has been made with published experimental data for steam condensing with velocities in the range 380–730 ft/s, i.e. turbulent vapour core and a laminar/turbulent condensate film. A further outcome of the comparison with experimental data is a rationalization of the Reynolds flux concept with less empirical modification.

Impact of Turbine Center Frame Wakes on Downstream Rows in Heavy-Duty Low-Pressure Turbine

2019 ◽  
Vol 142 (1) ◽  
Author(s):  
Sara Biagiotti ◽  
Juri Bellucci ◽  
Michele Marconcini ◽  
Andrea Arnone ◽  
Gino Baldi ◽  
...  
Keyword(s):  
Experimental Data ◽  
Low Pressure ◽  
Numerical Approach ◽  
Forced Response ◽  
Operating Conditions ◽  
Response Analysis ◽  
Test Case ◽  
Low Pressure Turbine ◽  
Harmonic Content ◽  
The Impact

Abstract In this work, the effects of turbine center frame (TCF) wakes on the aeromechanical behavior of the downstream low-pressure turbine (LPT) blades are numerically investigated and compared with the experimental data. A small industrial gas turbine has been selected as a test case, composed of a TCF followed by the two low-pressure stages and a turbine rear frame (TRF) before the exhaust plenum. Full annulus unsteady computations of the whole low-pressure module have been performed. Two operating conditions, full (100%) and partial (50%) load, have been investigated with the aim of highlighting the impact of TCF wakes convection and diffusion through the downstream rows. Attention was paid to the harmonic content of rotors’ blades. The results show a slower decay of the wakes through the downstream rows in off-design conditions compared with the design point. The analysis of the rotors’ frequency spectrum reveals that moving from design to off-design conditions, the effect of the TCF does not change significantly. The harmonic contribution of all turbine components has been extracted, highlighting the effect of statoric parts on the last LPT blade. The TCF harmonic content remains the most relevant from an aeromechanic point of view as per experimental evidence, and it is considered for an forced response analysis (FRA) on the last LPT blade itself. Finally, aerodynamic and aeromechanic predictions have been compared with the experimental data to validate the numerical approach. Some general design solutions aimed at mitigating the TCF wakes impact are discussed.

Subchannel Analysis with Mechanistic Methods for Thermo-Hydro Dynamics in BWR Fuel Bundles

2006 ◽  
Author(s):  
Kentaro Imura ◽  
Kenji Yoshida ◽  
Isao Kataoka ◽  
Masanori Naitoh
Keyword(s):  
Experimental Data ◽  
Predictive Accuracy ◽  
Distribution Data ◽  
Two Phase ◽  
Cross Sectional ◽  
Operational Parameter ◽  
Transition Analysis ◽  
Operational Conditions ◽  
Void Distribution ◽  
The Impact

In order to predict the critical power or void fraction in BWR fuel bundles and the DNB heat flux of PWR fuel assemblies, the boiling transition analysis code called “CAPE” with mechanistic models has been developed in the IMPACT project by NUPEC. The objective of the CAPE code development is to perform with good accuracy the safety evaluation for a new type or improved fuel bundle design of BWR and PWR without full-scale experiments or any tuning parameters in the analysis code. In this study, the CAPE for BWR was validated by the test analysis for 8 × 8 fuel bundles comparing with the void distribution data of the experimental data, which was carried out under several operational conditions in a BWR. The computations were carried out by changing the operational parameter such as the inlet subcooling, mass flow rate and the power output of the fuel bundles. Resultantly, the thermal equilibrium quality at the outlet ranges from 2% to 25%. From these results, though the predictive accuracy of the analytical results are in close agreement with the experimental data, it was noted that the errors were relatively outstanding in some subchannels, which was surrounded by the heated fuel rods and partially unheated walls, such as an unheated rod, a water rod and a separation wall of the channel box. The reason for this error is thought to be that the cross sectional void distribution was partially distributed in such subchannels surrounded partially by unheated wall, so the multidimensional void distribution structure might be formed in these subchannels. Under such conditions, it is very important to take into consideration the multidimensional structure of the two-phase flow in subchannel, and perhaps improve the estimation or correlations for the distribution parameter, as well as the amount of void exchange between neighboring subchannels.

VLSI Hotspot Cooling Using Two-Phase Microchannel Convection

2002 ◽  
Author(s):  
Jae-Mo Koo ◽  
Sungjun Im ◽  
Eun Seok Cho ◽  
Ravi S. Prasher ◽  
Evelyn Wang ◽  
...  
Keyword(s):  
Boundary Conditions ◽  
Heat Sink ◽  
Junction Temperature ◽  
Microchannel Heat Sink ◽  
Signal Delay ◽  
Two Phase ◽  
Silicon Chips ◽  
Vlsi Chip ◽  
Spatially Varying ◽  
The Impact

Two-phase microchannel heat sinks are promising for the cooling of high power VLSI chips, in part because they can alleviate spatial temperature variations, or hotspots. Hotspots increase the maximum junction temperature for a given total chip power, thereby degrading electromigration reliability of interconnects and inducing strong variations in the signal delay on the chip. This work develops a modeling approach to determine the impact of conduction and convection on hotspot cooling for a VLSI chip attached to a microchannel heat sink. The calculation approach solves the steady-state two-dimensional heat conduction equations with boundary conditions of spatially varying heat transfer coefficient and water temperature profile. These boundary conditions are obtained from a one-dimensional homogeneous two-phase model developed in previous work, which has been experimentally verified through temperature distribution and total pressure drop measurements. The new simulation explores the effect of microchannels on hotspot alleviation for 20 mm × 20 mm silicon chips subjected to spatially varying heat generation totaling 150 W. The results indicate that a microchannel heat sink of thickness near 500 μm can yield far better temperature uniformity than a copper spreader of thickness 1.5 mm.

scholarly journals Impact of inter-particle collision on elbow erosion based on DSMC-CFD method

2021 ◽  
Author(s):  
Xiao-Yang Sun ◽  
Xue-Wen Cao
Keyword(s):  
Experimental Data ◽  
Direct Simulation Monte Carlo ◽  
Particle Collision ◽  
Percentage Error ◽  
Dsmc Method ◽  
Two Phase ◽  
Average Percentage ◽  
Average Percentage Error ◽  
The Impact ◽  
Elbow Erosion

AbstractIn this work, computational fluid dynamics (CFD) is used to study elbow erosion due to a gas–solid two-phase flow. In particular, the direct simulation Monte Carlo (DSMC) method is used to study the impact of inter-particle collision on the erosion behavior. The two-way coupled Euler–Lagrange method is used to solve the gas–solid flow, and the DSMC method is used to consider the collision behavior between particles. The effects of key factors, such as the particle concentration distribution and inter-particle collision, on the erosion ratio are evaluated and discussed. The effectiveness of the method is verified from experimental data. The results show that the inter-particle collision significantly influences the particle movement path and erosion ratio. When the inter-particle collision is considered, the maximum erosion position is offset. The erosion model proposed by Oka et al., who used the DSMC method, agrees best with the experimental data, and the average percentage error decreases from 39.2 to 27.4%.

Comparison of experimental data and numerical simulation of two-phase flow pattern in vertical minichannel

2012 ◽  
Vol 33 (1) ◽  
pp. 63-71
Author(s):  
Jarosław Sowiński ◽  
Marek Krawczyk ◽  
Marek Dziubiński
Keyword(s):  
Experimental Data ◽  
Numerical Simulation ◽  
Boundary Conditions ◽  
Flow Pattern ◽  
Two Phase Flow ◽  
Phase Flow ◽  
Computational Domain ◽  
Two Phase ◽  
Ansys Fluent ◽  
Satisfactory Description

Comparison of experimental data and numerical simulation of two-phase flow pattern in vertical minichannel The aim of the study was the implementation of a numerical simulation of the air-water two-phase flow in the minichannel and comparing results obtained with the values obtained experimentally. To perform the numerical simulations commercial software ANSYS FLUENT 12 was used. The first step of the study was to reproduce the actual research installation as a three-dimensional model with appropriate and possible simplifications - future computational domain. The next step was discretisation of the computational domain and determination of the types of boundary conditions. ANSYS FLUENT 12 has three built-in basic models with which a two-phase flow can be described. However, in this work Volume-of-Fluid (VOF) model was selected as it meets the established requirements of research. Preliminary calculations were performed for a simplified geometry. The calculations were later verified whether or not the simplifications of geometry were chosen correctly and if they affected the calculation. The next stage was validation of the chosen model. After positive verification, a series of calculations was performed, in which the boundary conditions were the same as the starting conditions in laboratory experiments. A satisfactory description of the experimental data accuracy was attained.

Effect of the Shear Driven Liquid Wall Film on the Performance of Prefilming Airblast Atomizers

1998 ◽  
Author(s):  
Heiko Rosskamp ◽  
Michael Willmann ◽  
Jürgen Meisl ◽  
Robert Meier ◽  
Georg Maier ◽  
...  
Keyword(s):  
Film Flow ◽  
Two Phase Flow ◽  
Air Flow ◽  
Numerical Approach ◽  
Design Tool ◽  
Fuel Properties ◽  
Parameter Study ◽  
Phase Flow ◽  
Two Phase ◽  
Wall Film

Advanced prefilming airblast atomizers are widely used for low emission combustors since they deliver a fine spray almost independently of the fuel flow rate. The droplet spectrum produced by this type of atomizer results from the aerodynamic forces at the atomizer edge and from the fuel properties prior to the film disintegration. Therefore, the wall film temperature is an important parameter affecting the fuel properties and in turn the atomization quality. Even though this atomizer type became well investigated (Lefebvre 1989, Rizk et al. 1987, Sattelmayer et al. 1989), still no general quantitative relationship between atomizer design and spray quality could be established since the fuel state at the atomizer edge cannot be precisely predicted yet. In extending earlier experimental and theoretical work on airblast atomizers (Sattelmayer et al. 1989, Himmelsbach et al. 1994, Willmann et al. 1997) and recent advances in the numerical modeling of wall film flows (Rosskamp et al. 1997a), this paper presents a numerical approach to judge the effect of fuel mass flow, air flow and the film length (i. e. length of atomizer lip) on the temperature of the liquid at the atomizer edge. The computer code developed provides detailed information on the wall film flow and the nozzle wall temperature. For the prediction of heat transfer to the film a new model has been developed which is based on measurements of the internal film flow (Elsäßer et al 1997). This new numerical approach can serve as a design tool to evaluate the effects of design modifications during atomizer development with view to their effect on atomization performance. The paper includes the theory for two-phase flow modeling and a generic parameter study that points out that the liquid loading and the length of the atomizer lip are important parameters in atomizer design. The calculations presented in the paper emphasize the necessity of coupled two-phase flow calculations because the film strongly interacts with the gas phase and the predicted atomizer performance is sensitive to changes in the air flow.

Two-Phase Flow Large Eddy Simulations of a Staged Multipoint Swirling Burner: Comparison Between Euler-Euler and Euler-Lagrange Descriptions

2017 ◽  
Author(s):  
Léo Cunha Caldeira Mesquita ◽  
Aymeric Vié ◽  
Sébastien Ducruix
Keyword(s):  
Liquid Phase ◽  
Boundary Conditions ◽  
Flame Structure ◽  
Large Eddy Simulations ◽  
Spray Angle ◽  
Pilot Injection ◽  
Two Phase ◽  
Large Eddy ◽  
Tulip Flame ◽  
The Impact

A two-staged swirling burner is numerically simulated through large eddy simulations. The impact of the liquid phase modeling approach is evaluated comparing the Eulerian and Lagrangian frameworks for two different operation points, full pilot injection and full multipoint injection. For the full multipoint injection, since the operation point is closer to a Lean Premixed Prevaporized (LPP) regime, both liquid phase models present similar flame structure (an M flame). For the full pilot injection, Eulerian and Lagrangian approaches result in different flames for equivalent boundary conditions: the Eulerian simulation produces a ‘tulip’ flame, while the Lagrangian spray forms a lifted flame. To assess the model sensitivity to boundary conditions parameters, complementary Lagrangian simulations are made varying injected droplets’ diameter and spray angle, this time resulting in a ‘tulip’ flame very similar to the Eulerian one. Finally, a last Eulerian simulation is made, where the injected droplets’ diameter is increased, still leading to a ‘tulip’ flame, showing that the strong interaction between liquid phase and flame highly impact the results.

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