Analysis of Gas Turbine Rim Cavity Ingestion With Axial Purge Flow Injection

2019 ◽  
Author(s):  
Christopher W. Robak ◽  
Amir Faghri ◽  
Karen A. Thole
Keyword(s):  
Experimental Data ◽  
Complex Geometry ◽  
Numerical Study ◽  
Three Dimensional ◽  
Labyrinth Seal ◽  
Cfd Modeling ◽  
Navier Stokes ◽  
Purge Flow ◽  
Inner Diameter ◽  
Urans Cfd

Abstract Turbine rim cavities require an adequate supply of cooling purge flow to prevent hot gas ingestion from overheating metal components beneath the gas path airfoils. Purge flow is typically introduced into rim cavities through a labyrinth seal at the inner diameter of the cavity, or through conduits in the metal walls of the rim cavity. This numerical study will focus on purge flow introduced through axial holes in the stationary side of a turbine realistic rim cavity. Three dimensional Unsteady Reynolds-average Navier-Stokes (URANS) CFD modeling is utilized to model of cavity sealing effectiveness as a function of axial purge flow rate. CFD modeling is compared with experimental data from the test turbine in the Steady Thermal Aero Research Turbine (START). Results show good agreement with experimental data, especially at lower purge flow rates. Analytical depictions of the flow field setup in the rim cavity are provided, explaining trends observed in experimental data. Differences in sealing effectiveness trends between the upper and lower portions of the rim cavity are predicted by CFD modeling, adding insight to ingestion phenomena in turbine realistic rim cavities with complex geometry and flow leakage paths.

Single Phase CFD Inside a Water Safety Valve

2010 ◽  
Author(s):  
Christophe Vallet ◽  
Je´roˆme Ferrari ◽  
Jean-Franc¸ois Rit ◽  
Fe´de´ric Dehoux
Keyword(s):  
Experimental Data ◽  
Single Phase ◽  
Safety Valve ◽  
Three Dimensional ◽  
Flow Coefficient ◽  
Cfd Modeling ◽  
Navier Stokes ◽  
Water Safety ◽  
Relief Valve ◽  
Valve Opening

In this paper, Computational Fluid Dynamics (CFD) modeling is used to improve the understanding of the liquid flow inside a safety valve and to predict both the hydraulic force acting on the disk and the flow coefficient Cv. The three-dimensional simulations are performed on a realistic geometry and with an unstructured hybrid mesh. Independent calculations are performed for several valve openings. Turbulence is simulated using the Reynolds-Averaged Navier-Stokes (RANS) model k – ω SST, and a single-phase flow is considered for simplification. First, sensitivity of results with boundary conditions and mesh fineness is analysed. The dependence of hydraulic parameters with the valve opening is then investigated and numerical results are compared to experimental data coming from a test rig reproducing industrial conditions. Results indicate firstly that the flow inside the valve is stationary and axisymmetric. Quantitative comparison with the experiment must account for cavitation which is not simulated. We show, however, the adequacy of our results with experimental data and that single phase CFD can provide valuable insights on cavitating relief valve flow.

Viscous Flow Computations on a Smooth Cylinders: A Detailed Numerical Study With Validation

2007 ◽  
Author(s):  
Guilherme Vaz ◽  
Christophe Mabilat ◽  
Remmelt van der Wal ◽  
Paul Gallagher
Keyword(s):  
Experimental Data ◽  
Viscous Flow ◽  
Numerical Study ◽  
Three Dimensional ◽  
Turbulence Models ◽  
Reynolds Numbers ◽  
Navier Stokes ◽  
Detached Eddy Simulation ◽  
Time Step ◽  
Drag Forces

The objective of this paper is to investigate several numerical and modelling features that the CFD community is currently using to compute the flow around a fixed smooth circular cylinder. Two high Reynolds numbers, 9 × 104 and 5 × 105, are chosen which are in the so called drag-crisis region. Using a viscous flow solver, these features are assessed in terms of quality by comparing the numerical results with experimental data. The study involves grid sensitivity, time step sensitivity, the use of different turbulence models, three-dimensional effects, and a RANS/DES (Reynolds Averaged Navier Stokes, Detached Eddy Simulation) comparison. The resulting drag forces and Strouhal numbers are compared with experimental data of different sources. Major flow features such as velocity and vorticity fields are presented. One of the main conclusions of the present study is that all models predict forces which are far from the experimental values, particularly for the higher Reynolds numbers in the drag-crisis region. Three-dimensional and unsteadiness effects are present, but are only fully captured by sophisticated turbulence models or by DES. DES seems to be the key to better solve the flow problem and obtain better agreement with experimental data. However, its considerable computational demands still do not allow to use it for engineering design purposes.

Numerical Study of Slip Factor Model: Effect of Inlet Total Pressure and Gas Composition on the Performance Curve of Centrifugal Compressor

2011 ◽  
Author(s):  
M. R. Aligoodarz ◽  
M. H. Moshrefi A. ◽  
H. Karrabi ◽  
M. R. Soleimani Tehrani
Keyword(s):  
Experimental Data ◽  
Centrifugal Compressor ◽  
Total Pressure ◽  
Factor Model ◽  
Numerical Study ◽  
Three Dimensional ◽  
Cfd Modeling ◽  
Gas Composition ◽  
Slip Factor ◽  
Characteristic Map

Development of hardware and CFD codes, especially in turbulence model and optimization of numerical codes has led to increment in usage of CFD which is capable of simulating different experimental situations take place at laboratory. Particularly in issues related to turbo machinery, two-dimensional test of blades, three-dimensional investigation of different stages and studying the effect of different parameters are very costly. By means of CFD modeling all these issues are accessible. Actual flow within the compressor is three dimensional and fully turbulent due to geometry complexity, flow velocity and viscosity. For this reason it has become more and more popular to perform 3D numerical studies. In this study three-dimensional analysis of flow in a two stage centrifugal compressor is performed. Since no experimental data is available to evaluate the results of the present numerical analysis, validation is done by using experimental data of the gas turbine set up at Sharif University of Technology Laboratory. Numerical results are used for the evaluation of the slip factor models and finally, the effects of inlet gas composition and inlet total pressure on characteristic map are investigated.

CFD Modeling of Pulverized Coal Combustion in an Industrial Burner

2012 ◽  
Author(s):  
Marco Torresi ◽  
Bernardo Fortunato ◽  
Sergio Mario Camporeale ◽  
Alessandro Saponaro
Keyword(s):  
Experimental Data ◽  
Coal Combustion ◽  
Three Dimensional ◽  
Full Scale ◽  
Pulverized Coal ◽  
Cfd Modeling ◽  
Navier Stokes ◽  
Second Phase ◽  
Pulverized Coal Combustion ◽  
Char Burnout

The accurate prediction of pulverized coal combustion in industrial application still remains a great challenge. This is mainly due to the lack of high quality experimental data acquired during the operation of industrial plants. This work describes the CFD model used in order to numerically simulate the pulverized coal combustion of a full scale, swirl stabilized, aerodynamically staged, industrial burner. In particular, two different combinations of devolatilization and char burnout models were investigated comparing the numerical results with available experimental data obtained during a burner test carried out, in full-scale configuration, in a 50 MWth, fully instrumented, test rig. In order to avoid any unrealistic assumption on pulverized coal distribution at the burner inlet, the entire primary air duct for pulverized coal transportation has been considered. The main flow is computed solving the steady, incompressible, three-dimensional, Reynolds Averaged Navier-Stokes (RANS) equations, whereas the pulverized coal is simulated as a reacting discrete second phase in a Lagrangian frame of reference, computing the trajectories of the discrete phase entities, as well as heat and mass transfer. The numerical analysis confirms the very good burner performance obtained during the tests with a very low percentage of fixed carbon left in the ashes.

NUMERICAL STUDY OF DETONATION PROPAGATION IN VISCOUS TURBULENT FLOW IN A DUCT

2020 ◽  
Author(s):  
V. A. SABELNIKOV ◽  
◽  
V. V. VLASENKO ◽  
S. BAKHNE ◽  
S. S. MOLEV ◽  
...  
Keyword(s):  
Complex Geometry ◽  
Numerical Study ◽  
Navier Stokes ◽  
Detonation Waves ◽  
Detonation Propagation ◽  
Eddy Simulation ◽  
Detonation Structure ◽  
Classical Studies ◽  
Large Eddy ◽  
Physical Effects

Gasdynamics of detonation waves was widely studied within last hundred years - analytically, experimentally, and numerically. The majority of classical studies of the XX century were concentrated on inviscid aspects of detonation structure and propagation. There was a widespread opinion that detonation is such a fast phenomenon that viscous e¨ects should have insigni¦cant in§uence on its propagation. When the era of calculations based on the Reynolds-averaged Navier- Stokes (RANS) and large eddy simulation approaches came into effect, researchers pounced on practical problems with complex geometry and with the interaction of many physical effects. There is only a limited number of works studying the in§uence of viscosity on detonation propagation in supersonic §ows in ducts (i. e., in the presence of boundary layers).

scholarly journals Dynamics of Single Droplet Splashing on Liquid Film by Coupling FVM with VOF

Processes ◽  
2021 ◽  
Vol 9 (5) ◽  
pp. 841
Author(s):  
Yuzhen Jin ◽  
Huang Zhou ◽  
Linhang Zhu ◽  
Zeqing Li
Keyword(s):  
Liquid Film ◽  
Weber Number ◽  
Stokes Equations ◽  
Numerical Study ◽  
Three Dimensional ◽  
Navier Stokes ◽  
Single Droplet ◽  
Navier Stokes Equations ◽  
Volume Method ◽  
The Relationship

A three-dimensional numerical study of a single droplet splashing vertically on a liquid film is presented. The numerical method is based on the finite volume method (FVM) of Navier–Stokes equations coupled with the volume of fluid (VOF) method, and the adaptive local mesh refinement technology is adopted. It enables the liquid–gas interface to be tracked more accurately, and to be less computationally expensive. The relationship between the diameter of the free rim, the height of the crown with different numbers of collision Weber, and the thickness of the liquid film is explored. The results indicate that the crown height increases as the Weber number increases, and the diameter of the crown rim is inversely proportional to the collision Weber number. It can also be concluded that the dimensionless height of the crown decreases with the increase in the thickness of the dimensionless liquid film, which has little effect on the diameter of the crown rim during its growth.

A CFD-Based Parametric Study on Modification of Discrete Sister Holes Location for the Film Cooling Flow

2014 ◽  
Author(s):  
Siavash Khajehhasani ◽  
Bassam Jubran
Keyword(s):  
Film Cooling ◽  
Numerical Study ◽  
Three Dimensional ◽  
Navier Stokes ◽  
Base Case ◽  
Spanwise Direction ◽  
Cooling Performance ◽  
Cooling Flow ◽  
Lift Off ◽  
The Individual

A numerical study on the effects of sister holes locations on film cooling performance is presented. This includes the change of the location of the individual discrete sister holes in the streamwise and spanwise directions, where each one of these directions includes 9 different locations, The simulations are performed using three-dimensional Reynolds-Averaged Navier Stokes analysis with the realizable k–ε model combined with the standard wall function. The variation of the sister holes in the streamwise direction provides similar film cooling performance as the base case for both blowing ratios of 0.5 and 1. On the other hand, the spanwise variation of the sister holes’ location has a more prominent effect on the effectiveness. In some cases, as a result of the anti-vortices generated from the sister holes and the repositioning of the sister holes in the spanwise direction, the jet lift-off effect notably decreases and more volume of coolant is distributed in the spanwise direction.

scholarly journals Choice and Limits of a Fluid Model for the Numerical Study in Dynamic Fluid Structure Interaction Problems

2003 ◽  
Author(s):  
Jean Franc¸ois Sigrist ◽  
Christian Laine ◽  
Dominique Lemoine ◽  
Bernard Peseux
Keyword(s):  
Stokes Equations ◽  
Numerical Study ◽  
Fluid Model ◽  
Three Dimensional ◽  
Navier Stokes ◽  
Linear Solution ◽  
Fluid Structure ◽  
Design Engineers ◽  
Inviscid Incompressible Fluid ◽  
Basic Fluid

This paper is related to the study of a nuclear propulsion reactor prototype for the French Navy. This prototype is built on ground and is to be dimensioned toward seismic loading. The dynamic analysis takes the coupled fluid structure analysis into account. The basic fluid models used by design engineers are inviscid incompressible or compressible. The fluid can be described in a bidimensional by slice or a three-dimensional approach. A numerical study is carried out on a generic problem for the linear FSI dynamic problem. The results of this study are presented and discussed. As a conclusion, the three-dimensional inviscid incompressible fluid appears to be the best compromise between the description of physical phenomena and the cost of modeling. The geometry of the reactor is such that large displacements of the structure in the fluid can occur. Therefore, the linearity hypothesis might not be longer valid. The case of large amplitude imposed oscillating motion of a cylinder in a confined fluid is numerically studied. A CFD code is used to investigate the fluid behavior solving the NAVIER-STOKES equations. The forces induced on the cylinder by the fluid are computed and compared to the linear solution. The limit of the linear model can then be exhibited.

Large Eddy Simulation of Cross Flow in Pipe Junction

2018 ◽  
Author(s):  
Jiajun Chen ◽  
Yue Sun ◽  
Hang Zhang ◽  
Dakui Feng ◽  
Zhiguo Zhang
Keyword(s):  
Large Eddy Simulation ◽  
Stokes Equations ◽  
Numerical Study ◽  
Three Dimensional ◽  
Cross Flow ◽  
Exciting Force ◽  
Navier Stokes ◽  
Pipe Network ◽  
Eddy Simulation ◽  
Large Eddy

Mixing in pipe junctions can play an important role in exciting force and distribution of flow in pipe network. This paper investigated the cross pipe junction and proposed an improved plan, Y-shaped pipe junction. The numerical study of a three-dimensional pipe junction was performed for calculation and improved understanding of flow feature in pipe. The filtered Navier–Stokes equations were used to perform the large-eddy simulation of the unsteady incompressible flow in pipe. From the analysis of these results, it clearly appears that the vortex strength and velocity non-uniformity of centerline, can be reduced by Y-shaped junction. The Y-shaped junction not only has better flow characteristic, but also reduces head loss and exciting force. The results of the three-dimensional improvement analysis of junction can be used in the design of pipe network for industry.

Effects of Tip Clearance on Hot Streak Migration in a High-Subsonic Single-Stage Turbine

2000 ◽  
Author(s):  
Daniel J. Dorney ◽  
Douglas L. Sondak
Keyword(s):  
Experimental Data ◽  
Three Dimensional ◽  
Single Stage ◽  
Rotor Blades ◽  
Tip Clearance ◽  
Navier Stokes ◽  
Radial Spreading ◽  
Rotor Surface ◽  
Hot Streak ◽  
Turbine Airfoils

Experimental data have shown that combustor temperature non-uniformities can lead to the excessive heating of first-stage rotor blades in turbines. This heating of the rotor blades can lead to thermal fatigue and degrade turbine performance. The results of recent studies have shown that variations in the circumferential location, or clocking, of the first-stage vane airfoils can be used to minimize the adverse effects of the hot streaks due to the hot fluid mixing with the cooler fluid contained in the vane wake. In addition, the effects of the hot streak/airfoil count ratio on the heating patterns of turbine airfoils have been quantified. In the present investigation, three-dimensional unsteady Navier-Stokes simulations have been performed for a single-stage high-pressure turbine geometry operating in high subsonic flow to study the effects of tip clearance on hot streak migration. Baseline simulations were initially performed without hot streaks to compare with the experimental data. Two simulations were then performed with a superimposed combustor hot streak; in the first the tip clearance was set at the experimental value, while in the second the rotor was allowed to scrape along the outer case (i.e., the limit as the tip clearance goes to zero). The predicted results for the baseline simulations show good agreement with the available experimental data. The simulations with the hot streak indicate that the tip clearance increases the radial spreading of the hot fluid, and increases the integrated rotor surface temperature compared to the case without tip clearance.

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