bluuebunny/crossref_metadata_2025_split huggingface dataset:
Heat Transfer for High Aspect Ratio Rectangular Channels in a Stationary Serpentine Passage With Turbulated and Smooth Surfaces
Authors: Smith Matthew A. , Mathison Randall M. , Dunn Michael G. 
Published: November 2013

Heat transfer distributions are presented for a stationary three passage serpentine internal cooling channel for a range of engine representative Reynolds numbers. The spacing between the sidewalls of the serpentine passage is fixed and the aspect ratio (AR) is adjusted to 1:1, 1:2, and 1:6 by changing the distance between the top and bottom walls. Data are presented for aspect ratios of 1:1 and 1:6 for smooth passage walls and for aspect ratios of 1:1, 1:2, and 1:6 for passages with two surfaces turbulated. For the turbulated cases, turbulators skewed 45° to the flow are installed on the top and bottom walls. The square turbulators are arranged in an offset parallel configuration with a fixed rib pitch-to-height ratio (P/e) of 10 and a rib height-to-hydraulic diameter ratio (e/Dh) range of 0.100 to 0.058 for AR 1:1 to 1:6, respectively. The experiments span a Reynolds number range of 4,000 to 130,000 based on the passage hydraulic diameter.
While this experiment utilizes a basic layout similar to previous research, it is the first to run an aspect ratio as large as 1:6, and it also pushes the Reynolds number to higher values than were previously available for the 1:2 aspect ratio. The results demonstrate that while the normalized Nusselt number for the AR 1:2 configuration changes linearly with Reynolds number up to 130,000, there is a significant change in flow behavior between Re = 25,000 and Re = 50,000 for the aspect ratio 1:6 case. This suggests that while it may be possible to interpolate between points for different flow conditions, each geometric configuration must be investigated independently.
The results show the highest heat transfer and the greatest heat transfer enhancement are obtained with the AR 1:6 configuration due to greater secondary flow development for both the smooth and turbulated cases. This enhancement was particularly notable for the AR 1:6 case for Reynolds numbers at or above 50,000.
History of Short-Duration Measurement Programs Related to Gas Turbine Heat Transfer, Aerodynamics, and Aeroperformance at Calspan and OSU
Authors: Dunn Michael , Mathison Randall 
Published: November 2013

Short-duration facilities have been used for the past thirty-five years to obtain measurements of heat transfer, aerodynamic loading, vibratory response, film-cooling influence, purge flow migration, and aeroperformance for full-stage high-pressure turbines operating at design corrected conditions of flow function, corrected speed, and stage pressure ratio. This paper traces the development of experimental techniques now in use at The Ohio State University (OSU) Gas Turbine Laboratory (GTL) from initial work in this area at the Cornell Aeronautical Laboratory (CAL, later to become Calspan) in 1975 through to the present. It is intended to summarize the wide range of research that can be performed with a short-duration facility and highlight the types of measurements that are possible.
Beginning with heat-flux measurements for the vane and blade of a Garrett TFE 731-2 HP turbine stage with vane pressure-surface slot cooling, the challenge of each experimental program has been to provide data to aid turbine designers in understanding the relevant flow physics and help drive the advancement of predictive techniques. Through many different programs, this has involved collaborators at a variety of companies and experiments performed with turbine stages from Garrett, Allison, Teledyne, Pratt and Whitney, General Electric Aviation, Rocketdyne, Westinghouse, and Honeywell. The Vane/Blade Interaction measurement and CFD program, which ran from the early eighties until 2000, provided a particularly good example of what can be achieved when experimentalists and computational specialists collaborate closely. Before conclusion of this program in 2000, the heat-flux and pressure measurements made for this transonic turbine operated with and without vane trailing edge cooling flow were analyzed and compared to predictive codes in conjunction with engineers at Allison, United Technologies Research Center, Pratt and Whitney, and GE Aviation in jointly published papers.
When the group moved to OSU in 1995 along with the facility used at Calspan, refined techniques were needed to meet new research challenges such as investigating blade damping and forced response, measuring aeroperformance for different configurations, and preparing for advanced cooling experiments that introduced complicating features of an actual engine to further challenge computational predictions. This required conversion of the test-gas heating method from a shock-tunnel approach to a blowdown approach using a combustor emulator to also create inlet temperature profiles, the development of instrumentation techniques to work with a thin-walled airfoil with backside cooling, and the adoption of experimental techniques that could be used to successfully operate fully cooled turbine stages (vane row cooled, blade row cooled, and proper cavity purge flow provided). Further, it was necessary to develop techniques for measuring the aeroperformance of these fully cooled machines.
Aerodynamic Simulation of a High-Pressure Centrifugal Fan for Process Industries
Authors: Corsini Alessandro , Delibra Giovanni , Rispoli Franco , Sheard Anthony G. , Venturini Paolo 
Published: November 2013

Large centrifugal fans in cement factories operate in an aggressive environment, as the cement particles dispersed in the flow are responsible for strong blade surface erosion that leads to performance degradation.
This paper reports on the simulation of the flow field in a large centrifugal fan designed for process industry applications. The aerodynamic investigation, at a preliminary level, highlights the critical regions inside the device and suggests possible modification to increase its duty life.
This paper reports on the simulation of the flow field in a large centrifugal fan designed for process industry applications. The aerodynamic investigation, at a preliminary level, serves the aim of highlighting the critical regions inside the device and suggest possible modification to increase its duty life.
In the paper we show the results of numerical computations carried out with the finite volume open-source code OpenFOAM using Multiple Reference Frame methodology. Reynolds Averaged Navier-Stokes equations for incompressible flow were solved with standard eddy-viscosity k-ε model in order to explore the aerodynamic behaviour of the fan in near-design operations. The incompressible flow hypothesis was adopted even if locally Mach number can exceed 0.5. In fact in this case the pressure-rise does not lead to a variation of the density able to affect the velocity field divergence.
Given the high performance of the investigated impeller, the present work has a twofold objective. First, we seek to define an accurate numerical methodology to investigate high-pressure radial fans. Second, we provide detailed analysis of the inlet ring-impeller-volute assembly inner workings under realistic distorted inflow conditions.
The results provide the evolution of the pressure field in order to validate the accuracy of the simulation in reproducing the motion inside the fan that was fundamental for credible particle dispersion reproduction. We then investigate the three-dimensional flow field through the impeller in order to provide details about the secondary flow structures that develop within the blade vanes.
Modelling of Hydraulic Seals Using an Axisymmetric Volume of Fluid Method (VOF)
Authors: Mathews Hans-Christian , Morvan Hervé , Peduto Davide , Wang Yi , Young Colin , Bauer Hans-Jörg 
Published: November 2013

Hydraulic seals are used in aero engines because of their excellent sealing properties. Sealing of oil inside bearing chambers is extremely important as leakage of oil into internal spaces of the engine increases the oil consumption and can result in undesirable effects, ranging from cosmetic to mechanical. A robust dimensioning of the seal is therefore essential. However, the maximum pressure capacity of the hydraulic seal is not always determined accurately enough with many of the existing design approaches, so a high safety factor must be used. It is desirable to keep improving the accuracy of these methods, in particular to handle ever larger pressure differences.
A new dimensionless design method is therefore introduced here to improve the determination of the maximum pressure capacity. This paper reports on a numerical CFD investigation using an axisymmetric Volume-of-Fluid (VOF) method building on the work of Young and Chew [1]. The numerical results are validated with the results of a two-shaft test rig, alongside analytical calculation results. Additionally, a parametric study based on CFD simulations is performed to identify dominant influence quantities. The parameters include the fluid properties of oil, the shaft speeds and the geometry parameters of the seal. Employing a data reduction approach, a new dimensionless number is introduced which allows the presentation of experimental and numerical results of the hydraulic seal in a dimensionless form. Based on this representation, a correlation is proposed, which shows a very promising trend.
This validated CFD investigation and subsequent correlation introduced here show significant potential for the dimensionless description of hydraulic seals and their maximum pressure capacity.
Optimization of Reduced Kinetic Models for Reactive Flow Simulations
Authors: Gokulakrishnan P. , Joklik R. , Viehe D. , Trettel A. , Gonzalez-Juez E. , Klassen M. 
Published: November 2013

A robust optimization scheme, known as rkmGen, for reaction rate parameter estimation has been developed for the generation of reduced kinetics models of practical interest for reactive flow simulations. It employs a stochastic optimization algorithm known as Simulated Annealing, and is implemented in C++ and coupled with Cantera, a chemical kinetics software package, to automate the reduced kinetic mechanism generation process. Reaction rate parameters in reduced order models can be estimated by optimizing against target data generated from a detailed model or by experiment. Target data may be of several different kinds: ignition delay time, blow-out time, laminar flame speed, species time-history profiles and species reactivity profiles. The software allows for simultaneous optimization against multiple target data sets over a wide range of temperatures, pressures and equivalence ratios.
In this paper, a detailed description of the optimization strategy used for the reaction parameter estimation is provided. To illustrate the performance of the software for reduced kinetic development, a number of test cases for various fuels were used: one-step, three-step and four-step global reduced kinetic models for ethylene, Jet-A and methane, respectively, and a fifty-step semi-global reduced kinetic model for methane. The fifty-step semi-global reduced kinetic model was implemented in the Star*CCM+ commercial CFD code to simulate Sandia Flame D using laminar flamelet libraries and compared with the experimental data. Simulations were also performed with the GRI3.0 mechanism for comparisons.
The FMT Criterion to Optimize the Quench Zone in RQL Combustors
Authors: Huang Yong , Liu Lei , Wang Fang , Wang Shaolin 
Published: November 2013

As environmental protection is more and more important, pollution emission in aircraft combustors should be low. The RQL (rich-quench-lean) technique is one of the promising ways to control NOx emissions from combustors. In RQL combustors, NOx is mostly produced in quench zone. So the optimization of quench zone is very important to control NOx emissions.
According to thermal NOx mechanism, NOx emissions are determined by residence times. For a RQL combustor all the mainflow fuel should be burned out in quench zone. Then the maximum residence time is the time for the flame to transport the longest distance. Based on the first-principle analysis of the flow and combustion in the quench zone, the FMT (flame mixing time) criterion for the optimization of quench jets has been proposed.
There are two typical quench ducts. One is the annular shape and the other is the can shape. The two types of ducts are similar but there are some differences between them. In this paper both of them were analyzed in terms of the FMT criterion. The maximum residence times calculated by FMT criterion were compared with the experiments by Chiappetta et. al. [3] and Holdeman & Chang[13] for annular and can combustors, respectively. The comparison shows the very good agreement between the maximum residence times calculated by FMT criterion and the experiments. That means the FMT criterion can be validated by both annular and can shape combustors. And the FMT criterion could be used to optimize the configuration of quench zones.
Staged Lean Catalytic Combustion of Gasified Biomass for Gas Turbine Applications: An Experimental Approach to Investigate Performance of Catalysts
Authors: Manrique Carrera Arturo , Jayasuriya Jeevan , Fransson Torsten 
Published: November 2013

Emission demands for gas turbine utilization will become more stringent in the coming years. Currently different techniques are used to reach low levels of NOx emissions. One possible solution is the Staged Lean Catalytic Combustion. In this concept a catalysts arrangement is used to generate high temperature combustion gases. The high temperature gases could be used to feed a second combustion stage in which more fuel is injected.
In this work a series of experiments were performed at the Catalytic Combustion High Pressure Test Facility at the Royal Institute of Technology (KTH) in Sweden. The fuel used was a simulated gasified biomass and the catalytic combustor consisted of an arrangement of different catalysts, e.g. bimetallic, hexaaluminates, and perovskites catalysts. These were used as, ignition catalyst, medium temperature catalyst and high temperature catalyst respectively.
The tests were performed between 5 and 13.5 bar, and the overall conversion varied between 60% and 70% and the temperature of flue gases could reach 750°C and contains high level of oxygen. The determining factor to control the exit gas temperature was the richness of the mixture (λ value). On the other hand, the increased pressure had a moderate negative effect in the overall fuel conversion. This effect is stronger at leaner mixtures compared to richer ones. Moreover, λ value and also pressure affected the temperature distribution along the reactor.
The utilization of a lean catalytic combustion approach makes possible the use of a post catalytic combustion. In this region additional fuel is injected to fully burn the exiting gases and increase the exit temperature to the desired levels. This staged lean catalytic combustion approach could resemble moderate levels exhaust gas recirculation techniques and/or high air temperature combustion and it is also briefly examined in the present work.
Numerical Investigation on Flow and Heat Transfer in a Lattice (Matrix) Cooling Channel
Authors: Hagari Tomoko , Ishida Katsuhiko 
Published: November 2013

Flow and heat transfer of lattice cooling channel are investigated numerically. Firstly, simulations are performed for two channels to reproduce the experimental results reported in open literatures. Based on the literatures, sub-channels consisting lattice network are designed with aspect ratio of near unity and crossing angle of 45 degrees. Predicted heat transfer patterns of primary surfaces have agreed qualitatively and quantitatively well with the experimental results. Cooling air turns mainly through turning at the end of each sub-channel. After impinging the sidewall, strong acceleration occurs at the entrance of the opposite sub-channel, which enhances local heat transfer.
Based on the above discussions, the present study also compares heat transfer coefficient of all surfaces (rib + primary) surrounding the sub-channel. The highest local heat transfer coefficient is found at rib surfaces. Predicted flow pattern indicates that a longitudinal vortex is formed in parallel to the sub-channel after impinging the sidewall, and that transient flow from one to another side of the sub-channels keeps the core of the vortex. This transient flow substantially contributes to the heat transfer enhancement at the upper edge of a rib surface, and more than half of total heat flux transfers through the rib. It follows that, in designing lattice cooling channel, rib surfaces should also be treated as heat transfer surface. Moreover, the effect of sub-channel (or rib) inclination angle on flow and heat transfer is examined. Rib inclination angle strongly affects translation flow between the lower and upper sub-channels and impingement at the sidewall. Further experimental investigation is expected in the near future.
Numerical Analysis of Pressure Losses in Diffuser and Tube Steam Partition Valves
Authors: Bianchini C. , Micio M. , Tarchi L. , Cortese C. , Imparato E. , Tampucci D. 
Published: November 2013

Control valves are one of the key steam turbine components both in terms of operational safety and flexibility. It is hence fundamental to correctly predict the valve characteristics at the various working conditions to accurately estimate machine performance and control logics. The aim of this work is to develop a simple method to predict pressure losses within the partition system to be used at preliminary design stage.
Two types of partition valves typically employed in real industrial steam turbines of different power (from 1MW to 100MW) are analysed. The first type exploits a diffuser-like shape to maximize the dynamic pressure recovery before the discharge into the impulse stage. The second type, based on simple tube geometry, increases the allowable flow rate, for the same valve seat, at the cost of higher pressure losses. Geometrical dimensions have been varied to cover a wide range of configurations employed in industrial applications. An exception is made for the diffuser angle and the relative fillet radius which were fixed to guarantee product standardization among the various machine sizes.
The flow is supposed axisymmetric and upstream reference condition for the entire study is 140 bar and 540 °C which are typical working conditions for such steam turbines. The influence of the shutter is also considered to properly characterize regulation of the steam flow on the basis of valve lift.
Pressure losses are first modelled dividing the partition valve into singular homogeneous parts such as the intake, the straight pipe, the diffuser and the discharge, for which simple correlations are available in literature. The overall characteristic curve is validated using CFD computations conducted with the steady state RANS solver available in the commercial code CFX exploiting the SST turbulence model.
The development of the correlation permitted to rapidly cover the selected range of geometries and conditions highlighting that dynamic pressure losses are the major sources of losses. Minimal passage area to discharge section ratio is hence a dimensionless value able to describe characteristic curves insensitively to any other geometrical parameter.
Internal Cooling Channels Design Investigations: Aerothermal Optimisation of Ribbed U-Bends
Authors: Lott Philippe T. , Lepot Ingrid , Chérière Emmanuel , Thirifay François , Semmler Klaus , Bénet Laura 
Published: November 2013

The design of turbine cooling systems remains one of the most challenging processes in engine development. Modern turbine cooling systems indeed invariably combine internal convection cooling with external film cooling in complex flow systems. The heat transfer and cooling processes are at the limit of current understanding and engine designers heavily rely on empirical tools and engineering judgment to produce new designs. These designs are moreover developed in the context of continuously increasing Turbine Entry Temperature (TET) as the latter leads to improvement of Specific Fuel Consumption (SFC). The present contribution fits into the frame of the ongoing FP7 ER-ICKA project. It focuses on achieving a significant progress in understanding turbine blade passages internal cooling systems by gathering high quality experimental data and by developing cooling state-of-the-art design capabilities based upon computer codes calibrated through these experimental data.
In this context, the paper will describe the design optimisation and analysis work performed for two different internal cooling passages configurations, namely a static leading edge LP configuration passage (baseline experimentally tested at Stuttgart University) and a rotating mid-chord HP configuration passage (baseline experimentally tested at ONERA). The aim of the work was to develop a design methodology to optimise turbulence promoting ribs shape and arraying to improve the thermal behaviour of the internal cooling passages while avoiding excessive head loss. The optimisation was driven using decoupled rib design parameters for each ribbed wall to enhance flow interactions and maximise disturbances, to maximise potential increase in Heat Transfer Coefficients (HTCs). Any improvement in the thermal behaviour of the cooling system may indeed allow to either reduce the coolant mass flow rate requirements or increase the TET.
To drive these optimisations, the ultimate target was hence to reduce the maximum blade metal temperature. To this end, suitable cost functions (objectives and constraints) have been derived and implemented. They will first be presented and discussed along with the parameterisations, so as to define the complete optimisation specification. The computational chain setup, among which the challenging mesh regeneration choices set based on a mesh dependence study will then be detailed. Validation of the CFD evaluation against the experimental results will be described for the static baseline configuration at least (rotating test measurements are still ongoing) and the optimisation results, which have led to significant gains in HTCs, will finally be analysed, data mining techniques allow to identify key parameters, path taken in the conception space and major trends.