A Model for Cylindrical Hole Film Cooling—Part II: Model Formulation, Implementation and Results

2012 ◽  
Vol 134 (6) ◽  
Author(s):  
Tilman auf dem Kampe ◽  
Stefan Völker
Keyword(s):  
Flow Field ◽  
Film Cooling ◽  
Cfd Simulation ◽  
Three Dimensional ◽  
Vortex Pair ◽  
Experimental Investigations ◽  
Source Terms ◽  
Complex Flow ◽  
General Applicability ◽  
Cooling Hole

A model to simulate flows ejected from cylindrical film cooling holes in 3D-CFD without meshing the cooling hole geometry has been developed. It uses a correlation-based prediction of the complete three-dimensional flow field in the vicinity of a film hole exit based on characteristic film cooling parameters that is presented in part I of this two-part paper. The model describes the film-jet in terms of its shape and the distribution of temperature and velocity components within the film-jet body. For example, the characteristic counter-rotating vortex pair in the film-jet is modeled. Adding source terms to the transport equations for mass, momentum, and energy locally, the correlation-based prediction of the film-jet flow field is imposed onto a 3D-CFD simulation. Source terms are specified in the vicinity of a film hole exit, within a region representative of the volume occupied by the film jet. Each node within this source volume is treated individually in order to model the complex flow structure of the film-jet. The model has successfully been implemented in a commercial CFD code. Its general applicability has been tested and proven. The model’s predictive capability is compared to detailed CFD calculations and experimental investigations. A grid requirement study has been conducted, showing that the film cooling model delivers reasonable predictions of the surface temperature distributions downstream of the ejection location using relatively coarse grids. A minimum grid resolution requirement has been identified.

A Model for Cylindrical Hole Film Cooling: Part II—Model Formulation, Implementation and Results

2010 ◽  
Author(s):  
Tilman auf dem Kampe ◽  
Stefan Vo¨lker
Keyword(s):  
Flow Field ◽  
Film Cooling ◽  
Cfd Simulation ◽  
Three Dimensional ◽  
Vortex Pair ◽  
Experimental Investigations ◽  
Source Terms ◽  
Complex Flow ◽  
General Applicability ◽  
Cooling Hole

A model to simulate flows ejected from cylindrical film cooling holes in 3D-CFD without meshing the cooling hole geometry has been developed. It uses a correlation-based prediction of the complete three-dimensional flow field in the vicinity of a film hole exit based on characteristic film cooling parameters that is presented in part I of this two-part paper [1]. The model describes the film-jet in terms of its shape and the distribution of temperature and velocity components within the film-jet body. For example, the characteristic counter-rotating vortex pair in the film-jet is modeled. Adding source terms to the transport equations for mass, momentum and energy locally, the correlation-based prediction of the film-jet flow field is imposed onto a 3D-CFD simulation. Source terms are specified in the vicinity of a film hole exit, within a region representative of the volume occupied by the film jet. Each node within this source volume is treated individually in order to model the complex flow structure of the film-jet. The model has successfully been implemented in a commercial CFD code. Its general applicability has been tested and proven. The model’s predictive capability is compared to detailed CFD calculations and experimental investigations. A grid requirement study has been conducted, showing that the film cooling model delivers reasonable predictions of the surface temperature distributions downstream of the ejection location using relatively coarse grids. A minimum grid resolution requirement has been identified.

Research Analysis and Experiment Study on Flow Field of Hydrodynamic Coupling

2011 ◽  
Vol 418-420 ◽  
pp. 2006-2011
Author(s):  
Rui Zhang ◽  
Cheng Jian Sun ◽  
Yue Wang
Keyword(s):  
Flow Field ◽  
Cfd Simulation ◽  
Two Phase Flow ◽  
Three Dimensional ◽  
Internal Flow ◽  
Phase Flow ◽  
Complex Flow ◽  
Two Phase ◽  
Operation Conditions ◽  
Hydrodynamic Coupling

CFD simulation and PIV test technology provide effective solution for revealing the complex flow of hydrodynamic coupling’s internal flow field. Some articles reported that the combination of CFD simulation and PIV test can be used for analyzing the internal flow field of coupling, and such analysis focuses on one-phase flow. However, most internal flow field of coupling are gas-fluid two-phase flow under the real operation conditions. In order to reflect the gas-fluid two-phase flow of coupling objectively, CFD three-dimensional numerical simulation is conducted under two typical operation conditions. In addition, modern two-dimensional PIV technology is used to test the two-phase flow. This method of combining experiments and simulation presents the characteristics of the flow field when charging ratios are different.

Improved Film Cooling Effectiveness by Placing a Vortex Generator Downstream of Each Hole

2008 ◽  
Author(s):  
David L. Rigby ◽  
James D. Heidmann
Keyword(s):  
Film Cooling ◽  
Density Ratio ◽  
Three Dimensional ◽  
Vortex Generator ◽  
Vortex Pair ◽  
Navier Stokes ◽  
Dramatic Improvement ◽  
Freestream Velocity ◽  
Film Cooling Effectiveness ◽  
Cooling Hole

Calculations are presented demonstrating the effect of placing a delta vortex generator downstream of a film cooling hole. The effects of blowing ratio, density ratio, and spanwise pitch are included in the study. Flow over a flat plate with film cooling holes oriented at a 30 degree angle was investigated. The Reynolds numbers based on the freestream velocity and the hole diameter was 11,300. The simulation was performed using the Glenn-HT code, a full three-dimensional Navier-Stokes solver using the Wilcox k-ω turbulence model. A structured multi-block grid was used with approximately one million cells, and average y+ values on the order of unity. Local and span averaged effectiveness are presented. Analysis and visualization of the flow are presented as well as a discussion on the mechanisms which contribute to the dramatic improvement in effectiveness. The results demonstrate that the delta vortex generator was able to annihilate the up-wash vortex pair produced by the film hole and produce a down-wash pair downstream.

Experimental Study on Hydrodynamic Performance of Mini-AUV in Non-Uniform Flow Field

2019 ◽  
Author(s):  
Jiayuan Zhuang ◽  
Jian Cao ◽  
Yumin Su ◽  
Lei Zhang ◽  
Xianzhao Yu
Keyword(s):  
Flow Field ◽  
Three Dimensional ◽  
Lateral Force ◽  
Uniform Flow ◽  
Hydrodynamic Performance ◽  
Experimental Investigations ◽  
Complex Flow ◽  
Three Dimensional Flow ◽  
Drift Angle ◽  
Current Profiler

Abstract Experimental investigations of hydrodynamic performance of mini-AUV in non-uniform flow field were conducted in the basin of Harbin Engineering University, the revolved body and flat body of mini-AUV model were tested respectively. The three dimensional flow fields were generated by local jet of the underwater pump, and circulated in the basin. The three dimensional velocity distributions at different positions were measured by a Doppler current profiler. The three component balance was used to measure the drag, lateral force and yawing moment acting on the mini-AUV models depending on drift angle in the flow field, and the influence of complex flow field to the hydrodynamic performance of mini-AUV indicated that drag was not sensitive to drift angle and yawing moment was increased obviously. The conducted experiments could supply reference to the maneuverability research of mini-AUV in real marine environments in the future.

Large Eddy Simulation of Film Cooling Flow From an Inclined Cylindrical Jet

2003 ◽  
Author(s):  
Sumanta Acharya ◽  
Mayank Tyagi
Keyword(s):  
Flow Field ◽  
Film Cooling ◽  
Three Dimensional ◽  
Navier Stokes ◽  
Wake Region ◽  
Complex Flow ◽  
Mixing Processes ◽  
Hairpin Vortices ◽  
Flow Measurements ◽  
Large Eddy

Predictions of turbine blade film cooling have traditionally employed Reynolds averaged Navier Stokes (RANS) solvers and two-equation models for turbulence. Evaluation of several versions of such models have revealed that the existing two equation models fail to resolve the anisotropy and the dynamics of the highly complex flow field created by the jet-crossflow interaction. A more accurate prediction of the flow field can be obtained from large eddy simulations (LES) where the dynamics of the larger scales in the flow are directly resolved. In the present paper, such an approach has been used, and results are presented for a row of inclined cylindrical holes at blowing ratios of 0.5 and 1, and a Reynolds number of 11100 and 22200 respectively based on the jet velocity and hole diameter. Comparison of the time-averaged LES predictions with the flow measurements of Lavrich and Chiappetta [1] shows that LES is able to predict the flow field with reasonable accuracy. The unsteady three-dimensional flow field is shown to be dominated by packets of hairpin shaped vortices. The dynamics of the hairpin vortices in the wake region of the injected jet and their influence on the unsteady wall heat transfer is presented. Generation of “hot spots” and their migration on the film-cooled surface is associated with the entrainment induced by the hairpin structures. Several geometric properties of a “mixing interface” around hairpin coherent structures are presented to illustrate and quantify their impact on the entrainment rates and mixing processes in the wake region.

Large Eddy Simulation of Film Cooling Flow From an Inclined Cylindrical Jet

2003 ◽  
Vol 125 (4) ◽  
pp. 734-742 ◽  
Author(s):  
Mayank Tyagi ◽  
Sumanta Acharya
Keyword(s):  
Flow Field ◽  
Film Cooling ◽  
Three Dimensional ◽  
Navier Stokes ◽  
Wake Region ◽  
Complex Flow ◽  
Mixing Processes ◽  
Hairpin Vortices ◽  
Flow Measurements ◽  
Large Eddy

Predictions of turbine blade film cooling have traditionally employed Reynolds-averaged Navier-Stokes solvers and two-equation models for turbulence. Evaluation of several versions of such models have revealed that the existing two-equation models fail to resolve the anisotropy and the dynamics of the highly complex flow field created by the jet-crossflow interaction. A more accurate prediction of the flow field can be obtained from large eddy simulations (LES) where the dynamics of the larger scales in the flow are directly resolved. In the present paper, such an approach has been used, and results are presented for a row of inclined cylindrical holes at blowing ratios of 0.5 and 1 and Reynolds numbers of 11,100 and 22,200, respectively, based on the jet velocity and hole diameter. Comparison of the time-averaged LES predictions with the flow measurements of Lavrich and Chiappetta (UTRC Report No. 90-04) shows that LES is able to predict the flow field with reasonable accuracy. The unsteady three-dimensional flow field is shown to be dominated by packets of hairpin-shaped vortices. The dynamics of the hairpin vortices in the wake region of the injected jet and their influence on the unsteady wall heat transfer are presented. Generation of “hot spots” and their migration on the film-cooled surface are associated with the entrainment induced by the hairpin structures. Several geometric properties of a “mixing interface” around hairpin coherent structures are presented to illustrate and quantify their impact on the entrainment rates and mixing processes in the wake region.

Building Block Experiments in Discrete Hole Film Cooling

2015 ◽  
Author(s):  
Kevin J. Ryan ◽  
Filippo Coletti ◽  
Christopher J. Elkins ◽  
John K. Eaton
Keyword(s):  
Boundary Layer ◽  
Pressure Gradient ◽  
Building Block ◽  
Film Cooling ◽  
Three Dimensional ◽  
Vortex Pair ◽  
Mean Velocity ◽  
Jet Trajectory ◽  
Dominant Feature ◽  
Cooling Hole

This paper reports a series of building block experiments for discrete hole film cooling. Seven different configurations, including variations in injection wall curvature, mainstream pressure gradient, and boundary layer thickness are measured for a round film cooling hole, inclined 30 degrees at injection, and operated at a blowing ratio of unity. Full three dimensional, three component velocity fields and scalar coolant concentration fields are acquired using Magnetic Resonance Imaging (MRI) techniques. The results show the effect of varying the mainstream condition on the mean coolant concentration distribution and mean velocity field, including the counter-rotating vortex pair (CVP), a dominant feature of jet in crossflow type flows. The present study focuses on an analysis of the building block configurations only possible with full three dimensional velocity and concentration fields. Several scalar parameters including normalized perimeter, jet trajectory, maximum coolant concentration, and coolant concentration spread are extracted from the collected data and compared across the different configurations. The results indicate that the pressure gradient variations have the strongest effect on the calculated quantities, the boundary layer slightly less, and the curvature very little.

Influence of a Honeycomb Facing on the Flow Through a Stepped Labyrinth Seal

2000 ◽  
Vol 124 (1) ◽  
pp. 140-146 ◽  
Author(s):  
V. Schramm ◽  
K. Willenborg ◽  
S. Kim ◽  
S. Wittig
Keyword(s):  
Flow Field ◽  
Three Dimensional ◽  
Theoretical Work ◽  
Labyrinth Seal ◽  
Honeycomb Structure ◽  
Experimental Investigations ◽  
Labyrinth Seals ◽  
Numerical Predictions ◽  
Flow Through ◽  
Aero Engines

This paper reports numerical predictions and measurements of the flow field in a stepped labyrinth seal. The theoretical work and the experimental investigations were successfully combined to gain a comprehensive understanding of the flow patterns existing in such elements. In order to identify the influence of the honeycomb structure, a smooth stator as well as a seal configuration with a honeycomb facing mounted on the stator wall were investigated. The seal geometry is representative of typical three-step labyrinth seals of modern aero engines. The flow field was predicted using a commercial finite volume code with the standard k-ε turbulence model. The computational grid includes the basic seal geometry as well as the three-dimensional honeycomb structures.

Implicit LES for Shaped-Hole Film Cooling Flow

2017 ◽  
Author(s):  
Todd A. Oliver ◽  
Joshua B. Anderson ◽  
David G. Bogard ◽  
Robert D. Moser ◽  
Gregory Laskowski
Keyword(s):  
Film Cooling ◽  
Density Ratio ◽  
Vortex Pair ◽  
Cooling Flow ◽  
Blowing Ratio ◽  
Eddy Simulation ◽  
Mean Temperature ◽  
Cooling Hole ◽  
The Mean ◽  
Adiabatic Effectiveness

Results of a recent joint experimental and computational investigation of the flow through a plenum-fed 7-7-7 shaped film cooling hole are presented. In particular, we compare the measured adiabatic effectiveness and mean temperature against implicit large eddy simulation (iLES) for blowing ratio approximately 2, density ratio 1.6, and Reynolds number 6000. The results overall show reasonable agreement between the iLES and the experimental results for the adiabatic effectiveness and gross features of the mean temperature field. Notable discrepancies include the centerline adiabatic effectiveness near the hole, where the iLES under-predicts the measurements by Δη ≈ 0.05, and the near-wall temperature, where the simulation results show features not present in the measurements. After showing this comparison, the iLES results are used to examine features that were not measured in the experiments, including the in-hole flow and the dominant fluxes in the mean internal energy equation downstream of the hole. Key findings include that the flow near the entrance to the hole is highly turbulent and that there is a large region of backflow near the exit of the hole. Further, the well-known counter-rotating vortex pair downstream of the hole is observed. Finally, the typical gradient diffusion hypothesis for the Reynolds heat flux is evaluated and found to be incorrect.

Time-Averaged and Time-Accurate Aerodynamic Effects of Forward Rotor Cavity Purge Flow for a High-Pressure Turbine: Part I—Analytical and Experimental Comparisons

2012 ◽  
Author(s):  
Brian R. Green ◽  
Randall M. Mathison ◽  
Michael G. Dunn
Keyword(s):  
High Pressure ◽  
Flow Field ◽  
Film Cooling ◽  
Pressure Ratio ◽  
Three Dimensional ◽  
Unsteady Aerodynamics ◽  
Flow Path ◽  
Field Analysis ◽  
High Pressure Turbine ◽  
Purge Flow

The effect of rotor purge flow on the unsteady aerodynamics of a high-pressure turbine stage operating at design corrected conditions has been investigated both experimentally and computationally. The experimental configuration consisted of a single-stage high-pressure turbine with a modern film-cooling configuration on the vane airfoil as well as the inner and outer end-wall surfaces. Purge flow was introduced into the cavity located between the high-pressure vane and the high-pressure disk. The high-pressure blades and the downstream low-pressure turbine nozzle row were not cooled. All hardware featured an aerodynamic design typical of a commercial high-pressure ratio turbine, and the flow path geometry was representative of the actual engine hardware. In addition to instrumentation in the main flow path, the stationary and rotating seals of the purge flow cavity were instrumented with high frequency response, flush-mounted pressure transducers and miniature thermocouples to measure flow field parameters above and below the angel wing. Predictions of the time-dependent flow field in the turbine flow path were obtained using FINE/Turbo, a three-dimensional, Reynolds-Averaged Navier-Stokes CFD code that had the capability to perform both steady and unsteady analysis. The steady and unsteady flow fields throughout the turbine were predicted using a three blade-row computational model that incorporated the purge flow cavity between the high-pressure vane and disk. The predictions were performed in an effort to mimic the design process with no adjustment of boundary conditions to better match the experimental data. The time-accurate predictions were generated using the harmonic method. Part I of this paper concentrates on the comparison of the time-averaged and time-accurate predictions with measurements in and around the purge flow cavity. The degree of agreement between the measured and predicted parameters is described in detail, providing confidence in the predictions for flow field analysis that will be provided in Part II.

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