bluuebunny/crossref_metadata_2025 huggingface dataset:
Evaluating the Effects of Internal Impingement Cooling on a Film Cooled Turbine Blade Leading Edge
Authors: Ravelli Silvia , Dobrowolski Laurene , Bogard David G.
Published: January 2011

The main goal of this work was to evaluate the influence of impingement cooling on the cooling performance on a film cooled turbine blade leading edge. Cooling performance was quantified in terms of overall effectiveness, i.e. the normalized external surface temperature. Numerical simulations, using the commercial code FLUENT, were carried out for a leading edge model corresponding to an experimental model tested previously. The leading edge geometry consisted of three rows of holes positioned along the stagnation line and at ±25°. Three different impingement plate configurations were investigated. Two impingement plate configurations had a single row of holes along the center so that the impingement jets were directed on the stagnation line in between coolant hole entrances. These configurations had varying hole diameters such that impingement jet velocity varied by a factor of two. The third impingement plate configuration had two rows of holes with each row was placed in between the coolant hole entrances along the off stagnation lines. A configuration with no impingement plate was also investigated. For these simulations the realizable k-ε turbulence model was used. All experimental conditions were matched including the density ratio of 1.5 and blowing ratios of 1.0 and 2.0. The numerical simulations were consistent with experiments in showing that the overall effectiveness was only slightly improved by the impingement cooling. This small effect on overall effectiveness was shown to be due to conjugate effects including a reduction of convective cooling within the coolant holes when impingement cooling was used.
Experimental Measurements and Computational Predictions for an Internally Cooled Simulated Turbine Vane With 90 Degree Rib Turbulators
Authors: Dees Jason E. , Bogard David G. , Ledezma Gustavo A. , Laskowski Gregory M. , Tolpadi Anil K.
Published: January 2011

An experimental and computational conjugate heat transfer study of an internally cooled, scaled-up simulated turbine vane with internal rib turbulators was performed. The conjugate nature of the model allowed for the effects of the internal ribs to be seen on the external overall effectiveness distribution. The enhanced internal heat transfer coefficient caused by the ribs increased the cooling capacity of the internal cooling circuit, lowering the overall metal temperature. External surface temperatures, internal surface temperatures, and coolant inlet and exit temperatures were measured and compared to data obtained from a non-ribbed model over a range of internal coolant Reynolds numbers. Internal rib turbulators were found to increase the overall effectiveness on the vane external surface by up to 50% relative to the non-ribbed model. Additionally, comparisons between the experimental measurements and computational predictions are presented.
High Temperature Fast Response Aerodynamic Probe
Authors: Lenherr Christian , Kalfas Anestis I. , Abhari Reza S.
Published: January 2011

In order to advance the technology for measurements in higher temperature flows, a novel miniature (diameter 2.5 mm) fast response probe that can be applied in flows with temperatures of up to 533K (500°F) has been developed. The primary elements of the probe are two piezoresistive pressure transducers that are used to measure the unsteady pressure and unsteady velocity field, as well as the steady temperature. Additional temperature and strain gauge sensors are embedded in the shaft to allow a much higher degree of robustness in the use of this probe. The additional temperature sensor in the shaft is used to monitor and correct the heat flux through the probe shaft, facilitating thermal management of the probe. The strain gauge sensor is used to monitor and control probe shaft vibration. Entirely new packaging technology had to be developed to make possible the use of this probe at such high temperatures. Extensive calibration and thermal cycling of the probe used to bound the accuracy and the robustness of the probe. This novel probe is applied in the one-and-1/2-stage, unshrouded axial turbine at ETH Zurich; this turbine configuration is representative of a high work aero-engine. The flow conditioning stretch upstream of the first stator is equipped with a recently designed hot streak generator. Several parameters of the hot streak, including temperature, radial and circumferential position, and shape and size can be independently controlled. The interactions between the hot streak and the secondary flow present a perfect scenario to verify the probe’s capability to measure under real engine conditions. Therefore, measurements with the novel probe have been made in order to prove the principle and to detail the interaction effects with blade row pressure gradients and secondary flows.
LES Flow Control Simulations for Highly Loaded Low Pressure Turbine Airfoil (L1A) Using Pulsed Vortex Generator Jets
Authors: Ibrahim Mounir B. , Kartuzova Olga , Doucet Daniel J. , Volino Ralph J.
Published: January 2011

Seven different cases were examined experimentally and computationally to study LPT flow control using pulsed VGJs for the L1A airfoil. These cases represent a combination of variation in Reynolds number, Re (25,000, 50,000 and 100,000), based on the suction surface length and the nominal exit velocity from the cascade, blowing ratio, B (from 0.25 to 1), dimensionless frequency, F (from 0.035 to 0.56) and duty cycle, DC (10% and 50%). The data was obtained for the pressure distribution along the airfoil and downstream in the wake as well as for velocity profiles at six different stations downstream of the suction peak. The CFD was done with LES utilizing version 6.3.26 of the finite-volume code ANSYS Fluent. The CFD did provide further insight to better understand the physics of flow control. The comparison between CFD and experimental results for Cp, velocity profiles and Ψint is reasonable for all cases examined. Two of the cases examined did indicate that the higher DC could compensate for the lower F value. However, the effect of increasing the frequency appears to be stronger than increasing the DC value. The results from CFD using the Q-Criterion clearly illustrate how a separation bubble will persist at the lower frequency case (Case (2)) and the disturbances created from the jet flow do not have enough energy or time to travel further downstream to cause reattachment. On the other hand, the higher frequency case (Case (6)) did exhibit a penetration of the disturbance created by the jet into the separated region and caused reattachment, especially at the trailing edge. It appears that the jet was capable of breaking the large bubble into smaller ones with reattachment in between.
Numerical Study on Condensing Flow in Low Pressure Cylinder of a 300MW Steam Turbine
Authors: Li Liang , Li Yu , Wu Lianwei , You Wei , Li Jun , Feng Zhenping
Published: January 2011

The flow in low pressure (LP) cylinder of steam turbine is the well-known non-equilibrium condensing flow. If the LP cylinder is designed based on the equilibrium condensation theory, the flow parameters in the actual non-equilibrium condensing flow are different from the design condition, which will bring to additional ‘off-design’ losses besides the non-equilibrium losses due to spontaneous nucleation. In order to evaluate the difference between equilibrium and non-equilibrium condensing flows, as well as the ‘off-design’ losses, the hypothetical equilibrium condensing flow and the actual non-equilibrium condensing flow in the LP cylinder of a 300MW steam turbine were simulated by using the ANSYS CFX 11.0 software. The non-equilibrium condensing flow was computed in an Enlerian-Eulerian frame with the classical nucleation model. The computation domain involves all the six turbine stages of the LP cylinder, in which steam expands from superheated region to wet steam region. The non-equilibrium flow was compared with the equilibrium flow. It was found that the flow in the superheated steam stages is also affected by the ‘off-design’ operation of the wet steam stages. In the non-equilibrium flow, the thermal processes and the enthalpy drops in both superheated steam stages and wet steam stages are changed. The surface pressures and the wetness distributions in the wet steam stages are obviously varied. A rough evaluation was made to distinguish the ‘off-design’ and the non-equilibrium losses from the overall losses. For the LP cylinder investigated, the efficiency decrease caused by non-equilibrium losses in stage 5 is about 2%, and the efficiency decrease of about 0.26% due to ‘off-design’ losses is found in the wet steam stages (stage 4, 5, 6). In the superheated steam stages (stage 1, 2, 3), an efficiency increase of about 0.27% is obtained in stage 1, which indicates the positive influence of ‘off-design’ operation of the superheated steam stages in the LP cylinder investigated. The efficiencies of stage 2 and stage 3 are almost unchanged.
Experimental Investigation of the Nonlinear Response of Swirl Stabilized Flames to Equivalence Ratio Oscillations
Authors: Kim Kyu Tae , Lee Jong Guen , Quay Bryan D. , Santavicca Domenic A.
Published: January 2011

The nonlinear response of a swirl-stabilized flame to equivalence ratio oscillations was experimentally investigated in an atmospheric-pressure, high-temperature, lean-premixed model gas turbine combustor. To generate high-amplitude equivalence ratio oscillations, fuel was modulated using a siren type modulating device. The mixture ratio oscillations at the inlet of the combustion chamber were measured by the infrared absorption technique and the flame’s response, i.e., the fluctuation in the flame’s rate of heat release, was estimated by CH* chemiluminescence emission intensity. Phase-resolved CH* chemiluminescence images were taken to characterize the dynamic response of the flame. Results show that the amplitude and frequency dependence of the flame’s response to equivalence ratio oscillations is qualitatively consistent with the flame’s response to inlet velocity oscillations. The underlying physics of the nonlinear response of the flame to equivalence ratio oscillations, however, is associated with the intrinsically nonlinear dependence of the heat of reaction and burning velocity on the equivalence ratio. It was found that combustion cannot be sustained under conditions of high amplitude equivalence ratio oscillations. Lean blowoff occurs when the normalized amplitude of the equivalence ratio oscillation exceeds a threshold value. The threshold value is dependent on the mean equivalence ratio and modulation frequency.
Study of Flow Through a Stationary Ribbed Channel for Blade Cooling
Authors: Amano R. S. , Guntur Krishna , Martinez Lucci Jose , Ashitaka Yu
Published: January 2011

The firing temperature in gas turbine relates itself directly to the power output and the efficiency of the turbine. The higher the firing (operating) temperatures, higher the wall temperature of blades. However, an increase in the firing temperature is limited by the first stage blade material properties. This is because the higher firing temperature may cause a creep rupture, oxidizing, melting and ultimately failing of blades. Prior to blade cooling, the firing temperature was the same as the blade material temperature. Advancements in cooling technology have resulted in high firing temperatures with acceptable material temperatures. To better design the cooling channels and to improve heat transfer, many researchers are studying the flow patterns inside the cooling channels both experimentally and computationally. In this paper, the authors present the performance of three turbulence models using a Computational Fluid Dynamics code in comparison with the experimental values. To test the performance, a square duct was used with rectangular ribs oriented at 90° and 45° degree and placed at regular intervals. The channel also has bleed holes. The wall Nusselt numbers are compared in both the experimental and the computational results after suitable normalization. The Reynolds number is set to 10,000. The interactions between secondary flows and separation lead to very complex flow patterns. To accurately simulate these flows and heat transfer, both refined turbulence models and higher-order numerical schemes are indispensable for turbine designers to improve the cooling performance. The three-dimensional turbulent flows and heat transfer are numerically studied by using several different turbulence models, such as a non-linear low-Reynolds number k-ω and Reynolds Stress (RSM) models. In the k-ω model the cubic terms are included to represent the effects of extra strain-rates such as streamline curvature and three-dimensionality on both normal and shear turbulence stresses. The finite volume difference method incorporated with the higher-order bounded interpolation scheme has been employed in the present study. The outcome of this study helps to determine the best suitable turbulence model for future studies.
Experimental and Computational Analyses of Methane and Hydrogen Mixing in a Model Premixer
Authors: Akbari Amin , Hill Scott , McDonell Vincent , Samuelsen Scott
Published: January 2011

The mixing of fuel and air in combustion systems plays a key role in overall operability and emissions performance. Such systems are also being looked to for operation on a wide array of potential fuel types, including those derived from renewable sources such as biomass or agricultural waste. The optimization of premixers for such systems is greatly enhanced if efficient design tools can be utilized. The increased capability of computational systems has allowed tools such as computational fluid dynamics to be regularly used for such purpose. However, to be applied with confidence, validation is required. In the present work, a systematic evaluation of fuel mixing in a specific geometry which entails cross flow fuel injection into axial non-swirling air streams has been carried out for methane and hydrogen. Fuel concentration is measured at different planes downstream of the point of injection. In parallel, different CFD approaches are used to predict the concentration fields resulting from the mixing of fuel and air. Different steady turbulence models including variants of Reynolds Averaged Navier Stokes (RANS) have been applied. In addition, unsteady RANS and Large Eddy Simulation (LES) are used. To accomplish mass transport with any of the RANS approaches, the concept of the turbulent Schmidt number is generally used. As a result, the sensitivity of the RANS simulations to different turbulent Schmidt number values is also examined. In general, the results show that the Reynolds Stress Model, with use of an appropriate turbulent Schmidt number for the fuel used, provides the best agreement with the measured values of the variation in fuel distribution over a given plane in a relatively time efficient manner. It is also found that, for a fixed momentum flux ratio, both hydrogen and methane penetrate and disperse in a similar manner for the flowfield studied despite their significant differences in density and diffusivity.
Laminar Flame Speed Measurements and Modeling of Pure Alkanes and Alkane Blends at Elevated Pressures
Authors: Lowry William , de Vries Jaap , Krejci Michael , Petersen Eric , Serinyel Zeynep , Metcalfe Wayne , Curran Henry , Bourque Gilles
Published: January 2011

Alkanes such as methane, ethane, and propane make up a large portion of most natural gas fuels. Natural gas is the primary fuel used in industrial gas turbines for power generation. Because of this, a fundamental understanding of the physical characteristics such as the laminar flame speed is necessary. Most importantly, this information is needed at elevated pressures to have the most relevance to the gas turbine industry for engine design. This study includes experiments performed at elevated pressures, up to 10-atm initial pressure, and investigates the fuels in a pure form as well as in binary blends. Flame speed modeling was done using an improved version of the kinetics model that the authors have been developing over the past few years. Modeling was performed for a wide range of conditions, including elevated pressures. Experimental conditions include pure methane, pure ethane, 80/20 mixtures of methane/ethane, and 60/40 mixtures of methane/ethane at initial pressures of 1, 5, and 10 atm. Also included in this study are pure propane and 80/20 methane/propane mixtures at 1 and 5 atm. The laminar flame speed and Markstein Length measurements were obtained from a high-pressure flame speed facility using a constant-volume vessel. The facility includes optical access, a high-speed camera, a schlieren optical setup, a mixing manifold, and an isolated control room. The experiments were performed at room temperature, and the resulting images were analyzed using linear regression. The experimental and modeling results are presented and compared to previously published data. The data herein agree well with the published data. In addition, a hybrid correlation was created to perform a rigorous uncertainty analysis. This correlation gives the total uncertainty of the experiment with respect to the true value rather than reporting the standard deviation of a repeated experiment. Included in the data set are high-pressure results at conditions where in many cases for the single-component fuels few data existed and for the binary blends no data existed prior to this study. Overall, the agreement between the model and data is excellent.
Effect of Freestream Turbulence Intensity on Film Cooling Jet Structure and Surface Effectiveness Using PIV and PSP
Authors: Wright Lesley M. , McClain Stephen T. , Clemenson Michael D.
Published: January 2011

An experimental investigation of film cooling jet structure using two-dimensional, particle image velocimetry (PIV) has been completed for cylindrical, simple angle (θ = 35°) film cooling holes. The PIV measurements are coupled with detailed film cooling effectiveness distributions on the flat plate obtained using a steady state, pressure sensitive paint (PSP) technique. Both the flow and surface measurements were performed in a low speed wind tunnel where the freestream turbulence intensity was varied from 1.2% to 12.5%. With this traditional film cooling configuration, the blowing ratio was varied from 0.5–1.5 to compare the jet structure of relatively low and high momentum cooling flows. Velocity maps of the coolant flow (in the streamwise direction) are obtained on three planes spanning a single hole: centerline, 0.25D, and 0.5D (outer edge of the film cooling hole). From the seeded jets, time averaged, mean velocity distributions of the film cooling jets are obtained near the cooled surface. In addition, turbulent fluctuations are obtained for each flow condition. Combining the detailed flow field measurements obtained using PIV (both instantaneous and time averaged) with detailed film cooling effectiveness distributions on the surface (PSP), provides a more complete view of the coolant jet–mainstream flow interaction. Near the edge of the film cooling holes, the turbulent mixing increases, and as a result the film cooling effectiveness decreases. Furthermore, the PIV measurements show the increased mixing of the coolant jet with the mainstream at the elevated freestream turbulence level resulting in a reduction of the jet to effectively protect the film cooled surface.
Numerical Analysis of the Wave Topping Unit for Small Turbojet
Authors: Piechna Janusz , Cerpa Rafael , Marcin Staniszewski , Akbari Pezhman , Mu¨ller Norbert
Published: January 2011

The paper is focused on the numerical analysis of a wave topping unit used in a small turbojet engine. The analysis focuses on a four-port reverse flow (RF) wave rotor. The special feature of the considered wave rotor is its very high rotational speed. The wave rotor is connected directly with the common shaft between compressor and turbine, thus, the effects of Coriolis accelerations become important. In this study, first a one-dimensional model is used to estimate geometry of the wave rotor and port timings. Then, multi-dimensional analysis models are employed to predict the different flow characteristics inside the wave rotor channels. Three-dimensional flow features that reduce machine performance and influence rotor blade and duct wall thermal loads are identified.
A Mixed Data-Driven and Model Based Fault Classification for Gas Turbine Diagnosis
Authors: Loboda Igor , Yepifanov Sergey
Published: January 2011

In modern gas turbine health monitoring systems, the diagnostic algorithms based on gas path analysis may be considered as principal. They analyze gas path measured variables and are capable of identifying different faults and degradation mechanisms of gas turbine components (e.g. compressor, turbine, and combustor) as well as malfunctions of the measurement system itself. Gas path mathematical models are widely used in building fault classification required for diagnostics because faults rarely occur during field operation. In that case, model errors are transmitted to the model-based classification, which poses the problem of rendering the description of some classes more accurate using real data. This paper looks into the possibility of creating a mixed fault classification that incorporates both model-based and data-driven fault classes. Such a classification will combine a profound common diagnosis with a higher diagnostic accuracy for the data-driven classes. A gas turbine power plant for natural gas pumping has been chosen as a test case. Its real data with cycles of compressor fouling were used to form a data-driven class of the fouling. Preliminary qualitative analysis showed that these data allow creating a representative class of the fouling and that this class will be compatible with simulated fault classes. A diagnostic algorithm was created based on the proposed classification (real class of compressor fouling and simulated fault classes for other components) and artificial neural networks. The algorithm was subjected to statistical testing. As a result, probabilities of a correct diagnosis were determined. Different variations of the classification were considered and compared using these probabilities as criteria. The performed analysis has revealed no limitations for realizing a principle of the mixed classification in real monitoring systems.
Experimental Test on a Syngas Model Combustor With Flameless Technology
Authors: Lv Xuan , Cui Yufeng , Fang Aibing , Xu Gang , Yu Bin , Nie Chaoqun
Published: January 2011

The research of combustor for gas turbine using flameless combustion technology is in the stage of laboratory. This paper designs a flameless model combustor using syngas, which has similar flow structure with reverse-flow can-type combustors and therefore could be used in typical small gas turbine system. In this combustor, either the premixed or non-premixed mode can be selected, meanwhile the difference is discussed. CFD methods are used to design the flow field and emissions of a combustor with detailed mechanisms. How the distance between the nozzle and axis influences the recirculation zone is discussed and optimized in the Isight platform. In the experimental test, the emissions and dynamic pressure characteristics are the main focus. The results demonstrate that flameless combustion technology has potential to be applied in gas turbine with syngas for the aim of Ultra-low pollutant emission combustion, which can restrict emission in a low level meanwhile maintain combustion stability. Flameless combustion is a rising ultra-low-pollution combustion technology. However, in this combustor when pilot flame existed, in some conditions the thermoacoustic oscillation was observed. The CFD results illuminates that this combustor ensures the recirculation in the primary zone, meanwhile the position of the nozzle and injection’s velocity have significant effect to the flow field.
Utilization of Cold-Flow Numerical Simulation With Overset Grid Method in Development Process of Aeroengine Combustor
Authors: Makida Mitsumasa , Nakamura Naoki , Nozaki Osamu
Published: January 2011

In the TechCLEAN project of JAXA, a combustor for a small aircraft engine has been developed. The combustor was tuned to show the behavior of the Rich-Lean combustion through combustion tests under atmospheric and practical conditions. In the development process of the combustor, numerical simulation methods were also utilized as analysis tools to accelerate the development of the combustor. To use in the screening process of the combustor design, we focused on cost-effective simulation methods and adopted the cold-flow RANS simulation code UPACS which has been developed in JAXA. And to simplify the treatment of calculation grids of the combustor with complicated configuration, we also utilized combination of the overset grid method with the attached multi-block grid method. This simulation method was applied to three phases in the combustor development process; first to the analysis of the combustor configuration to adjust the overall pressure loss, secondly to the analysis of flame stability, and thirdly to the tuning of air flow ratio to optimize emission characteristics of full annular combustors. Finally, the full annular combustor was successively tuned to reduce NOx emissions to 38.1% of the ICAO CAEP4 standard under ICAO LTO cycles, also sustaining basic performances as an aircraft combustor.
Forced Vibrations of Bladings With the Random Technological Mistuning
Authors: Larin O. O.
Published: January 2011

An approach has been considered for analysis of forced vibrations for randomly mistuned bladed discs. It is based on stochastic reduced basis method and hypothesis of locally distributed mistuning, which could realise in blade-to-blade joints due to the deviation at the assemblage technology. The method gives an essential possibility to make an analysis using one sector model and allows for this case to use of industrial-size sector models of bladings. The numerical researches of steady-state forced vibrations of randomly mistuned bladed disk of a 3-rd stage low pressure cylinder of a steam turbine have been done.
Influence of Flame and Burner Transfer Matrix on Thermoacoustic Combustion Instability Modes and Frequencies
Authors: Campa Giovanni , Camporeale Sergio Mario
Published: January 2011

The main origin of combustion instability in modern gas turbines is considered to be related to the interaction between acoustic waves and flame perturbations. An important role is played by the characteristics of combustion chamber and burners, because they influence the operating conditions at which the instability may occur. Experimental tests carried out on single burner arrangements fail to give adequate indications for the design of a full scale combustion chamber, due to the interaction of the local flame fluctuations with the propagation of the pressure waves, that have a wavelength of the same order of magnitude of the main dimensions of the chamber. Therefore there is a large interest on developing techniques able to make use of the data gathered from tests carried out on a single burner for predicting the thermoacoustic behavior of the combustion chamber at full scale with its actual geometry. A three dimensional finite element code has been developed for predicting acoustically driven combustion instabilities in combustion systems with complex geometries. The code allows one to identify the frequencies at which thermoacoustic instabilities are expected and the growth rate of the pressure oscillations, at the onset of instability, under the hypothesis of linear behaviour of the acoustic waves. The code permits to represent heat release fluctuations through an n–τ Flame Transfer Function (FTF) model and to adopt the transfer matrix method for modelling the burners. The FTF and the burner transfer matrix (BTM), as well as the temperature field and the flame location, needed for the simulation, can be obtained from experimental tests. Moreover, the code is able to make use of the local distribution of n and τ that can be evaluated from computational fluid dynamic studies on the single burner. The paper shows the importance of the flame characteristics, such as dimensions and shape of the heat release zone and its location within the combustor, underlying their influence on the instability of the modes and so the potential of the proposed method as a design tool for defining the burner characteristics and the acoustic impedance at the boundaries of the combustion chamber.
LP Turbine Reynolds Lapse Phenomena: Time Averaged Area Traverse and Multistage CFD
Authors: Ku¨rner Matthias , Schneider Carsten , Rose Martin G. , Staudacher Stephan , Gier Jochen
Published: January 2011

The new LP turbine test rig “ATRD” at the Institute of Aircraft Propulsion Systems (ILA) at Stuttgart University has been used to study the detailed effects of Reynolds number variation. The two-stage LP turbine has been developed in a cooperation of ILA and MTU Aero Engines GmbH. Changes in the turbine characteristics are discussed. Five hole probe area traverse data has been acquired at exit from each row of aerofoils across a broad range of Reynolds numbers, over 88,000 down to 35,000. The experimental data is supported by multi-row steady CFD predictions. The behaviour of wakes, loss cores and secondary deviations is identified across the Reynolds number range. The present study is focusing on the effects of Reynolds number variation on the vane of the second stage.
A Quantitative Link Between Cold-Flow Scalar Unmixedness and NOx Emissions in a Conical Premixed Burner
Authors: Lacarelle Arnaud , Go¨ke Sebastian , Paschereit Christian O.
Published: January 2011

The feasibility of using cold flow measurements in a conical swirl-inducing burner to predict the fuel/air mixture probability density function (PDF) at the flame location in a staged premixed swirl-inducing burner is discussed in the present work. Particle Image Velocity (PIV) measurements are used to investigate the impact of the flame on the mean and coherent velocity field upstream of the premixed flame of a conical swirl-inducing burner. When the flame does not anchor inside the burner, a good agreement between the reacting and the cold-flow fields is ensured. The scalar mixing field, dominated by coherent concentration fluctuations, is thus marginally affected by the flame. In this case, a correction of the mixture PDF, recorded in a water test rig at the burner outlet with planar laser-induced fluorescence (PLIF), can be used to estimate the mixture PDF at the flame location. This correction is based on the exponential decay of the mixture variance associated with the flame-position information of the reacting flow. An experimental curve fitting and a chemical-reactor network model confirm that the resulting PDF approximates the real unmixedness at the flame better than the measured mixture PDF at the burner outlet. When the flame is anchored inside the burner, the correction approach does not apply anymore, due to the strong flow field changes. The methodology presented allows to quantitatively predict the mixture PDF at the flame location for different total powers, preheating temperatures, and equivalence ratios. The simple mixing model and reactor network model are able to satisfyingly capture the NOx emissions when the flame stabilizes completely downstream of the burner.
CH*/OH* Chemiluminescence Response of an Atmospheric Premixed Flame Under Varying Operating Conditions
Authors: Guyot Daniel , Guethe Felix , Schuermans Bruno , Lacarelle Arnaud , Paschereit Christian Oliver
Published: January 2011

In this work the relationship between the ratio of the global CH* and OH* flame chemiluminescece and the global equivalence ratio of a technically premixed swirl-stabilized flame is investigated. The burner allows for a modification of the premix fuel injection pattern. The global flame chemiluminescence is monitored by a high-sensitivity light spectrometer and multiple photo-multipliers. The photo-multipliers were equipped with narrow optical band-pass filters and recorded the flame’s OH*, CH* and CO2* chemiluminescence intensity. To ensure an approximately uniform equivalence ratio distribution in the combustion zone, the spatial OH* and CH* flame chemiluminescence was recorded simultaneously with one ICCD camera using a special optical setup, which incorporated among other things one fully reflective and one semi-reflective mirror and appropriate optical filters. The flame chemiluminescence intensity was mapped for a range of equivalence ratios and air mass flows. The mapping shows that (as stated for perfectly premixed flames in the literature) the OH*, CH* and CO2* intensity of the investigated flame depends linearly on the air mass flow and exponentially on the equivalence ratio (i.e., I = km * φβ). Hence for the investigated operating conditions (i.e., quasi premix conditions) the global CH*/OH* intensity can be employed as a measure of the global equivalence ratio for the operating conditions investigated in this work. However, the contribution of broadband CO2* chemiluminescence in the wave length range of CH* chemiluminescence has to be accounted for.
Evaluation of the LMI-Based Multivariable PID Controller Design for Turbo Aeroengines
Authors: He Ai , Tan Daoliang , Wang Xi , Wang Lei
Published: January 2011

A variety of PID control tuning rules have been proposed for single-input single-output systems, but there is still a lack of research on PID controller design for multi-input multi-output systems. The objective in this paper is to gain some insight into multi-variable PID controller design for gas turbine engines. First of all, we present an approach to design multi-variable PID controllers based on the pole placement technique in the framework of linear matrix inequalities. Then this paper makes a comparison of four multi-variable PID controller design methods including pole-placement, iterative LMI approach, cone complementarity, and sufficient LMI condition. In terms of numerical computation, control performance, and anti-disturbance, we make an attempt to evaluate their performance and give some guidelines to gas turbine engine control. Experimental results illustrate that the pole-placement and iterative LMI methods are slightly superior to others due to their robust performance and their ease of solution and implementation.
Multivariable Aeroengine PID Control With Amplitude Saturation: An LMI Solution
Authors: Tan Daoliang , He Ai , Wang Xi , Liu Yun
Published: January 2011

This paper presents an approach to automatic tuning of the parameters of a PID controller for the multivariable gas turbine engine control, taking into account amplitude saturation and model nonstrict-properness. First of all, we illustrate that the PID controller design problem can be transformed into seeking a static output feedback controller for some augmented state-space model. Then we compute an initial stabilizable parameters of the involved PID controller in the strictly proper case, using a well-known static output feedback algorithm. As far as a non-strictly proper model is concerned, this paper uses a degenerate linear transformation to change its output equation into a strictly proper form. The drawback of the initially computed PID controller lies in its high gains (triggering amplitude saturation) that prevent it from being applicable to practical gas turbine engine control. In this paper, we build on a linear matrix inequality (LMI) based antiwindup scheme to address the constraints from amplitude saturation. Both of these problems are formulated in the LMI framework and can be efficiently solved using off-the-shelf software. Experimental results show the promising performance of the proposed method.
Study on Rubbing Failure Between Fan Vanes and Spacer Ring of a Turbo-Fan Engine
Authors: Zhang Dayi , Chen Meng , Hong Jie , Dou Miansheng
Published: January 2011

The objective of the present work is the study of the rubbing failure between fan stator vanes and the spacer ring of a Turbo-Fan Engine. The similar failures appeared 2 times in this small turbo-fan engine. The failure mechanism is analysed, in which kinds of factors that could influence the clearance between the rotor and the stator are taken into account. The failure is analysed by means of both test characterizations and numerical simulation techniques. Firstly, a finite element model of the spline joints is used to calculate the stiffness of the fan-rotor considering the influence of locating surface clearance. Secondly, a traveling wave vibration analysis of the spacer ring is performed, as well as the analysis of the stator vane. Finally, the analysis of the vibration test data is performed. The test characterizations and numerical simulation results indicate that, for Engine-1, the large 2×vibration shows a rotor misalignment, at the same time the traveling wave resonance of the spacer ring occurs, these cause the appearance of the failure. For Engine-2, the failure is caused by the rotor unbalance vibration. Some improvement measures are proposed to avoid this failure.
Case Study: CODAG Power Plant for a Pleasure Boat: Theory - Project - Results
Authors: Venturini Marco , Venturini Giovanni
Published: January 2011

The gas turbine engine first went to sea in 1953 when the British Shipbuilding Company VOSPERS was selected to experiment with the gas turbine as a form of marine propulsion. The former Steam Gun Boat (SGB) HMS Grey Goose was rebuilt by the shipyard with the surprisingly sophisticated Rolls-Royce RM60 engine. Today, for any vessel project whose design function makes its speed or volume critical, the gas turbine has become a strong candidate for selection as a prime mover, due to its inherent power density and low weight. For marine use, the gas turbine is equipped with a power turbine in order to convert the energy in the exhaust gases into rotational energy. This energy is applied, via a shaft line, to a suitable propulsion system either by a direct mechanical drive system or by the intermediary of an electrical system: this is the case of yachts and mega yachts characterized by high speed performances. The case study concerns the motor yacht “OCI CIORNIE”, built by the shipyard PALMER JOHNSON in 1999 and powered with a CODAG (Combined Diesel and Gas) type propulsion plant made up of two diesel engines coupled to waterjets, via a reduction gear and by a gas turbine TF40, driving a surface piercing propeller (SPP) with Arneson transmission, via a reduction gearbox. According to expectations of the designer the top speed with the CODAG configuration was to be more than 55 knots while the speed with the only diesel engines running would be around 25 knots, but enough to reach the take off speed anyway. Instead, because of weight increase during the construction, the current maximum speed with the diesel propulsion is only 14÷16 knots, depending of the displacement and the sea condition, while the CODAG propulsion top speed is around 50÷52 knots. The paper will analyze the main steps of the development of the OCI CIORNIE project and will compare the performances of the planning stage with the final operating conditions of the yacht. Besides, the paper will consider, for the current displacement reached, the optimum distribution between the power of the diesel engines and the power of the gas turbine in order to obtain, for different speeds, the maximum range, the minimum wear and tear of the machines and, as a consequence, the minimum operating expenses, respecting the restrictions of the maximum torque on the gas turbine and on the diesel engines.
Optical Investigation of Profile Losses in a Linear Turbine Cascade
Authors: Alhaj Olga , Seume Joerg R.
Published: January 2011

Two or three dimensional flow visualisation is an active research field because of its non-intrusiveness. However, its application is often restricted to ideal laboratory conditions. Only few of the multi-dimensional flow visualization techniques have been developed into quantitative measurement techniques which are applicable to turbo machinery flow conditions. This paper demonstrates the application of completely optical measurements for the estimation of the loss coefficient of turbine blades in a linear cascade wind tunnel, which represents flow conditions close to the real but geometrically simplified and therefore more accessible. Two optical means were combined for this purpose. To determine the velocity field of the wake, two-component Particle Image Velocimetry (PIV) was employed. Tomographical Background Oriented Schlieren method (BOS), using 8 cameras placed in 180° around the cascade, was used for measuring a 3-D density field in the wake. For purposes of comparison, the traditional loss estimation method with 5-hole pressure probes accompanied the optical methods. Inlet parameters were measured with a Prandtl probe and a temperature sensor. The optical techniques are, once they are installed as in the present work, much faster than any other conventional method, e.g. pneumatic probes. Moreover, optical techniques can be used for investigation of transient flows.
Materials and Component Development for Advanced Turbine Systems: Project Summary
Authors: Alvin M. A.
Published: January 2011

Future hydrogen-fired or oxy-fuel turbines will likely experience an enormous level of thermal and mechanical loading, as turbine inlet temperatures (TIT) approach ∼1425–1760°C (∼2600–3200°F) with pressures of ∼300–625 psig, respectively. Maintaining the structural integrity of future turbine components under these extreme conditions will require (1) durable thermal barrier coatings (TBCs), (2) high temperature creep resistant metal substrates, and (3) effective cooling techniques. While advances in substrate materials have been limited for the past decades, thermal protection of turbine airfoils in future hydrogen-fired and oxy-fuel turbines will rely primarily on collective advances in the TBCs and aerothermal cooling. To support the advanced turbine technology development, the Office of Research and Development (ORD) at National Energy Technology Laboratory (NETL) has continued its collaborative research efforts with the University of Pittsburgh and West Virginia University, while working in conjunction with commercial material and coating suppliers. This paper presents the technical accomplishments that were made during FY09 in the initial areas of advanced materials, aerothermal heat transfer and non-destructive evaluation techniques for use in advanced land-based turbine applications in the Materials and Component Development for Advanced Turbine Systems project and introduces three new technology areas — high temperature overlayer coating development, diffusion barrier coating development, and oxide dispersion strengthened (ODS) alloy development that are being conducted in this effort.
Film Cooling Effect of Rotor-Stator Purge Flow on Endwall Heat/Mass Transfer
Authors: Papa M. , Srinivasan V. , Goldstein R. J.
Published: January 2011

Mass transfer measurements on the endwall and blade suction surfaces are performed in a five-blade linear cascade with a high-performance rotor blade profile. The effects of purge flow from the wheelspace cavity entering the hot gas path are simulated by injecting air through a slot upstream of the blade row at 45° to the endwall, for Reynolds number of 6×105 based on blade true chord and cascade exit velocity, and blowing ratios of 0.5, 1 and 1.5. Detailed maps of cooling effectiveness on the passage endwall and blade suction surface are generated for the cases of injection of naphthalene-free and naphthalene-saturated air. Oil-dot visualization indicates that with injection, a recirculation region is set up upstream of the leading edge, and the growth of the passage vortex is altered. The coolant exiting from the slot is drawn to the suction side of the blade and is pushed up along the suction surface of the blade by the secondary flow. For blowing ratios of 0.5 and 1.0, only a little coolant reaches the pressure side in the aft part of the passage. However, at a blowing ratio of 1.5, there is a dramatic change in the flow structure. Both the oil dot visualization and the cooling effectiveness maps indicate that at this blowing ratio, the coolant exiting the slot has sufficient momentum to closely follow the blade profile, and is not significantly entrained into the passage vortex. As a result, high cooling effectiveness values are obtained at the pressure side of the endwall, well into the mid-chord and aft portions of the blade passage.
Study on the Leakage and Deformation Characteristics of the Finger Seals by Using Numerical Simulation
Authors: Zhang Hai , Zheng Qun , Yue Guoqiang
Published: January 2011

Depending on the throttling process of finger pad gap and the kinetic energy dissipation within the finger gap, finger seal can reduce the fluid leakage. But the deformation of the finger will increase the finger pad gap, which results in the increasing of overall leakage. To evaluate the performances of the finger seal, we used a two-way fluid-structure interaction method to analyse the seal deformation and flow field through the finger seal simultaneously. The numerical analyses show that a strengthened finger seal or a convergent type pad can be considered to reduce the leakage flow through finger pad gap. Finger pad deformation depends mainly on the pressure difference, but not the finger pad gap. There is a strong vortex in the finger gap, which blocks the fluid leakage. The leakage fluid is divided into many small vortices, the kinetic energy of the leakage fluid is dissipated in such a process and its pressure is decreased. When the finger pad deformed, its high pressure end moves toward the shaft, if the pressure difference increases or the shaft oscillated, this end could touch the shaft surface. The position of the maximum radial movement of finger pad does not coincide with the position of the maximum deformation of finger pad, which means the finger pad will be twisted to some extent rather than simply lift.
Heat Transfer and Pressure Losses of W-Shaped Small Ribs at High Reynolds Numbers for Combustor Liner
Authors: Hagari Tomoko , Ishida Katsuhiko , Oda Takeo , Douura Yasushi , Kinoshita Yasuhiro
Published: January 2011

The present study investigates the heat transfer performance of W-shaped ribs in a rectangular channel with typical geometries and flow conditions for a combustor liner cooling passage. In order to assess the Reynolds number dependence on heat transfer enhancement by the ribs for the combustor cooling passage, experiments were conducted with channel Reynolds number ranging from 40,000 to 550,000. The ribs were located on one side of the channel and the rib height-to-hydraulic diameter ratio (e/Dh) was 0.006 to 0.014, which simulate the combustor liner cooling configurations. Rib pitch-to-height ratio (P/e) was 10. Rib-roughened copper plates with constant temperature were used to measure the averaged heat transfer coefficients. Measured results show that the heat transfer enhancements of about 3 were obtained over that of a flat plate at high Reynolds numbers for all cases. The slope of heat transfer coefficient becomes constant with increasing Reynolds number because of the laminar-turbulent transition around the ribs, which is considered to occur at Reynolds number based on rib height of about 1,000. Pressure loss measurements showed that the friction coefficients are constantly 3–4.5 times higher than those of a flat plate for a fully turbulent flow such as a combustor cooling passage. Pressure loss by ribs seems not to have a significant impact to the overall combustor performance. Numerical calculations were conducted additionally for all test cases. Predicted amount of heat released from the ribs contributes about 40% of overall heat release even for low ribs. Heat transfer on the rib surface is essential in the evaluation of the rib-roughened cooling passage.