Predicted Effects of Bearing Sump and Injection Pressures on Oil Labyrinth Leakage

2002 ◽  
Vol 125 (1) ◽  
pp. 316-325 ◽  
Author(s):  
S.-Y. Park ◽  
D. L. Rhode
Keyword(s):  
Injection Pressure ◽  
Computer Code ◽  
Operating Conditions ◽  
Navier Stokes ◽  
Vapor Flow ◽  
Buffer Gas ◽  
Labyrinth Seals ◽  
Process Gas ◽  
New Information ◽  
Wide Range

New information and an enhanced understanding concerning the oil vapor contaminant leaking through nonflooded oil labyrinth seals are provided. The results were obtained using a finite volume Navier-Stokes computer code that was extended to include the concentration transport equation. The minimum (i.e., critical) pressure and flow rate at which uncontaminated buffer gas must be injected to prevent oil vapor from leaking to the process gas was determined for a range of seal geometries and operating conditions. It was found that the variation of the critical buffer-gas injection pressure with bearing gas and process gas pressures, for example, was surprisingly small for the cases considered. In addition, the bearing gas and oil vapor flow rates for a wide range of bearing and injection (where present) pressures and geometries were determined for both buffered as well as nonbuffered seals.

Predicted Effects of Bearing Sump and Injection Pressures on Oil Labyrinth Leakage

2001 ◽  
Author(s):  
Sung-Young Park ◽  
David L. Rhode
Keyword(s):  
Injection Pressure ◽  
Computer Code ◽  
Operating Conditions ◽  
Navier Stokes ◽  
Vapor Flow ◽  
Buffer Gas ◽  
Labyrinth Seals ◽  
Process Gas ◽  
New Information ◽  
Wide Range

New information and an enhanced understanding concerning the oil vapor contaminant leaking through non-flooded oil labyrinth seals are provided. The results were obtained using a finite-volume Navier-Stokes computer code that was extended to include the concentration transport equation. The minimum (i.e. critical) pressure and flow rate at which un-contaminated buffer gas must be injected to prevent oil vapor from leaking to the process gas was determined for a range of seal geometries and operating conditions. It was found that the variation of the critical buffer-gas injection pressure with bearing gas and process gas pressures, for example, was surprisingly small for the cases considered. In addition, the bearing gas and oil vapor flow rates for a wide range of bearing and injection (where present) pressures and geometries were determined for both buffered as well as non-buffered seals.

Predicted Geometry Effects on Oil Vapor Flow Through Buffer-Gas Labyrinth Seals

2002 ◽  
Vol 125 (1) ◽  
pp. 193-200
Author(s):  
S.-Y. Park ◽  
D. L. Rhode
Keyword(s):  
Mass Transport ◽  
Mass Flow ◽  
Vapor Flow ◽  
Buffer Gas ◽  
Labyrinth Seals ◽  
Flow Area ◽  
Oil Film ◽  
Process Gas ◽  
Geometry Effects ◽  
Vapor Mass

Mass transport characteristics of buffer-gas labyrinth seals operating in the flooded, nonmist regime were studied using numerical simulations. Discussion is given of the extension, to account for oil vapor mass transport, of a finite volume computer code that was previously validated using nonoil labyrinth hot-film anemometer as well as leakage measurements. A parametric study was conducted to obtain a first understanding of oil vapor transport from the liquid film on the stator wall and to assist oil seal designers. Various geometry effects with various oil film lengths were investigated. It was found in the present investigation that increasing the buffer gas pressure can increase the oil vapor mass flow to the process gas due to increased evaporation from the liquid oil film. In addition, it was found that buffer-gas mass flow is mainly affected by the clearance and the total flow area of the buffer-gas injection.

An Investigation of Tip Force Characteristics of Brush Seals

2007 ◽  
Author(s):  
Mehmet Demiroglu ◽  
Mustafa Gursoy ◽  
John A. Tichy
Keyword(s):  
Cantilever Beam ◽  
Numerical Models ◽  
Operating Conditions ◽  
Beam Equation ◽  
Labyrinth Seals ◽  
Wide Range ◽  
Brush Seals ◽  
Cantilever Beam Equation ◽  
Super Alloy ◽  
Force Pressure

Thanks to their compliant nature and superior leakage performance over conventional labyrinth seals, brush seals found increasing use in turbomachinery. Utilizing high temperature super-alloy fibers and their compliance capability these seals maintain contact with the rotor for a wide range of operating conditions leaving minimal passage for parasitic leakage flow. Consequently, the contact force/pressure generated at seal rotor interface is of importance for sustained seal performance and longevity of its service life. Although some analytical and numerical models have been developed to estimate bristle tip pressures, they simply rely on linear beam equation calculations and other such assumptions for loading cases. In this paper, previously available analytical and/or numerical models for bristle tip force/pressure have been modified and enhanced. The nonlinear cantilever beam equation has been solved and results are compared to a linear cantilever beam equation solution to establish application boundaries for both methods. The results are also compared to experimental data. With the support of testing, an empirical model has been developed for tip forces under operating conditions.

Application of an Improved Streamline Curvature Approach to a Modern, Two-Stage Transonic Fan: Comparison With Data and CFD

2002 ◽  
Author(s):  
Keith M. Boyer ◽  
Walter F. O’Brien
Keyword(s):  
Three Dimensional ◽  
Operating Conditions ◽  
Navier Stokes ◽  
Model Parameters ◽  
Two Stage ◽  
Streamline Curvature ◽  
Wide Range ◽  
Improved Model ◽  
Transonic Fan ◽  
Streamline Curvature Method

A streamline curvature method with improvements to key loss models is applied to a two-stage, low aspect ratio, transonic fan with design tip relative Mach number of approximately 1.65. Central to the improvements is the incorporation of a physics-based shock model. The attempt here is to capture the effects of key flow phenomena relative to the off-design performance of the fan. A quantitative analysis regarding solution sensitivities to model parameters that influence the key phenomena over a wide range of operating conditions is presented. Predictions are compared to performance determined from overall and interstage measurements, as well as from a three-dimensional, steady, Reynolds-averaged Navier-Stokes method applied across the first rotor. Overall and spanwise comparisons demonstrate that the improved model gives reasonable performance trending and generally accurate results. The method can be used to provide boundary conditions to higher-order solvers, or implemented within novel approaches using the streamline curvature method to explore complex engine-inlet integration issues, such as time-variant distortion.

Viscous Flow Analysis in Mixed Flow Rotors

1980 ◽  
Vol 102 (1) ◽  
pp. 193-201 ◽  
Author(s):  
I. Khalil ◽  
W. Tabakoff ◽  
A. Hamed
Keyword(s):  
Viscous Flow ◽  
Stokes Equations ◽  
Flow Analysis ◽  
Flow Characteristics ◽  
Laminar Flows ◽  
Operating Conditions ◽  
Field Analysis ◽  
Navier Stokes ◽  
Stream Channels ◽  
Wide Range

A method for analyzing the viscous flow through turbomachine rotors is presented. The field analysis is based on the solution of the full Navier-Stokes equations over the rotor blade-to-blade stream channels. An Alternating-Direction-Implicit method is employed to carry out the necessary numerical integration of the elliptic governing equations. The flow analysis may be applied to various types of turbomachine rotors. Preliminarily, only the case of laminar flows are considered in this paper. The flow characteristics within the rotors of a radial inflow turbine and a radial bladed compressor are investigated over a wide range of operating conditions. Excellent results are obtained when compared with existing experimental data. The method of this analysis is quite general and can deal with wide range of applications. Possible modification of the present study to deal with turbulent flow cases are also identified.

Analytical Maps of Aerodynamic Damping as a Function of Operating Condition for a Compressor Profile

2006 ◽  
Author(s):  
Paul J. Petrie-Repar ◽  
Andrew McGhee ◽  
Peter A. Jacobs ◽  
Rowan Gollan
Keyword(s):  
Inviscid Flow ◽  
Operating Conditions ◽  
Navier Stokes ◽  
Compressor Cascade ◽  
Operating Condition ◽  
Flow Solver ◽  
Aerodynamic Damping ◽  
Wide Range ◽  
Contour Plots ◽  
Standard Configuration

In this paper, analytical maps of aerodynamic damping for a two-dimensional compressor cascade (Standard Configuration 10) are presented. The maps are shown as contour plots of the aerodynamic damping as a function of operating condition. The aerodynamic dampings were calculated by a linearized Navier-Stokes flow solver. The flutter boundaries over a wide range of operating conditions are clearly shown on the damping maps and were found to be strongly dependent on the mode frequency and the mode shape. Extremely low values of negative aerodynamic damping were predicted for some off-design operating conditions where flow separation occurred. A damping map was also constructed based on inviscid flow simulations. There were differences in the viscous and inviscid flutter boundaries particularly at off-design inflow angles. The extremely low values of negative aerodynamic damping were only predicted by the viscous simulations and not the inviscid simulations.

scholarly journals Meander-Like Shape Optimization of the Stator-Rotor Platform Cavity

2018 ◽  
Author(s):  
Paht Juangphanich ◽  
Guillermo Paniagua
Keyword(s):  
Geometry Optimization ◽  
Operating Conditions ◽  
Navier Stokes ◽  
Practical Implementation ◽  
Computational Domain ◽  
Optimization Strategy ◽  
Minimum Thickness ◽  
Ansys Fluent ◽  
Driving Mechanisms ◽  
Wide Range

Recent progress in additive manufacturing has enabled opportunities to explore novel stator rim geometries which can be implemented to improve cooling strategies in turbomachinery. This paper presents a simplified stationary geometry optimization strategy to produce enhanced stator-rotor cavity sealing and highlights main driving mechanisms. The stator and rotor rims were designed using a design strategy based on inspiration from the meandering of rivers. A minimum thickness of 2mm was maintained throughout the cavity to ensure a practical implementation. The computational domain comprised of the stator outlet, hub disk leakage cavity, and rotor platform was meshed using NUMECA Int. package, Hexpress. The numerical analysis required 3D Unsteady Reynolds Average Navier-Stokes to replicate vorticial structures using Ansys Fluent. The operating conditions were representative of engine-like conditions, exploring a wide range of massflow ratios from 1 to 3%. The optimization yielded designs that provide 30% reduction in rear platform temperature while minimizing coolant massflow. The applicability of the design was compared against 3D sector in both stationary and in rotation.

scholarly journals Numerical study of flame/vortex interactions in 2-D Trapped Vortex Combustor

2014 ◽  
Vol 18 (4) ◽  
pp. 1373-1387 ◽  
Author(s):  
Prasad Mishra ◽  
Renganathan Sudharshan ◽  
Kumar Ezhil
Keyword(s):  
Numerical Study ◽  
Flame Structure ◽  
Reaction Rates ◽  
Operating Conditions ◽  
Navier Stokes ◽  
Base Case ◽  
Primary Vortex ◽  
Vortex Interactions ◽  
Wide Range ◽  
Trapped Vortex

The interactions between flame and vortex in a 2-D Trapped Vortex Combustor are investigated by simulating the Reynolds Averaged Navier Stokes (RANS) equations, for the following five cases namely (i) non-reacting (base) case, (ii) post-vortex ignition without premixing, (iii) post-vortex ignition with premixing, (iv) pre-vortex ignition without premixing and (v) pre-vortex ignition with premixing. For the post-vortex ignition without premixing case, the reactants are mixed well in the cavity resulting in a stable ?C? shaped flame along the vortex edge. Further, there is insignificant change in the vorticity due to chemical reactions. In contrast, for the pre-vortex ignition case (no premixing); the flame gets stabilized at the interface of two counter rotating vortices resulting in reduced reaction rates. There is a noticeable change in the location and size of the primary vortex as compared to case (ii). When the mainstream air is premixed with fuel, there is a further reduction in the reaction rates and thus structure of cavity flame gets altered significantly for case (v). Pilot flame established for cases (ii) and (iii) are well shielded from main flow and hence the flame structure and reaction rates do not change appreciably. Hence, it is expected that cases (ii) and (iii) can perform well over a wide range of operating conditions.

Falling-Film Absorption Around Microchannel Tube Banks

2013 ◽  
Vol 135 (12) ◽  
Author(s):  
Ananda Krishna Nagavarapu ◽  
Srinivas Garimella
Keyword(s):  
Mass Transfer ◽  
Heat And Mass Transfer ◽  
Water Solution ◽  
Small Diameter ◽  
Operating Conditions ◽  
Test Facility ◽  
Vapor Flow ◽  
Falling Film ◽  
Flow Rates ◽  
Wide Range

An experimental investigation of heat and mass transfer in a falling-film absorber with microchannel tube arrays was conducted. Liquid ammonia–water solution flows in a falling-film mode around an array of small diameter coolant tubes, while vapor flows upward through the tube array counter-current to the falling film. This absorber was installed in a test facility consisting of all components of a functional single-effect absorption chiller, including a desorber, rectifier, condenser, evaporator, solution heat exchanger, and refrigerant precooler, to obtain realistic operating conditions at the absorber and to account for the influence of the other components in the system. Unlike studies in the literature on bench-top, single-component, single-pressure test stands, here the experiments were conducted on the absorber at vapor, solution, and coupling fluid conditions representative of space-conditioning systems in the heating and cooling modes. Absorption measurements were taken over a wide range of solution flow rates, concentrations, and coupling fluid temperatures, which simulated operation of thermally activated absorption systems at different cooling capacities and ambient conditions. These measurements are used to interpret the effects of solution and vapor flow rates, concentrations, and coupling fluid conditions on the respective heat and mass transfer coefficients.

scholarly journals Compressible Navier-Stokes Analysis of Floating Wind Turbine Rotor Aerodynamics

2018 ◽  
Author(s):  
M. Sergio Campobasso ◽  
Andrea G. Sanvito ◽  
Jernej Drofelnik ◽  
Adrian Jackson ◽  
Yang Zhou ◽  
...  
Keyword(s):  
Wind Turbine ◽  
Compressible Flow ◽  
Flow Analysis ◽  
Unsteady Aerodynamics ◽  
Operating Conditions ◽  
Navier Stokes ◽  
Offshore Wind Turbine ◽  
Rotor Aerodynamics ◽  
Wide Range ◽  
Turbine Rotors

The unsteady aerodynamics of floating offshore wind turbine rotors is more complex than that of fixed-bottom turbine rotors, due to additional rigid-body motion components enabled by the lack of rigid foundations; it is still unclear if low-fidelity aerodynamic models, such as the blade element momentum theory, provide sufficiently reliable input for floating turbine design requiring load data for a wide range of operating conditions. High-fidelity Navies-Stokes CFD has the potential to improve the understanding of FOWT rotor aerodynamics, and support the improvement of lower-fidelity aerodynamic analysis models. To accomplish these aims, this study uses an in-house compressible Navier-Stokes code and the NREL FAST engineering code to analyze the unsteady flow regime of the NREL 5 MW rotor pitching with amplitude of 4° and frequency of 0.2 Hz, and compares all results to those obtained with a commercial incompressible code and FAST in a previous independent study. The level of agreement of CFD and engineering analyses in each of these two studies is found to be quantitatively similar, but the peak rotor power of the compressible flow analysis is about 20 % higher than that of the incompressible analysis. This is possibly due to compressibility effects, as the instantaneous local Mach number is found to be higher than 0.4. Validation of the compressible flow analysis set-up, using an absolute frame formulation and low-speed preconditioning, is based on the analysis of the steady and yawed flow past the NREL Phase VI rotor.

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