bluuebunny/crossref_metadata_2025_split huggingface dataset:
Aerodynamic Performance of Novel Lightweight Turbine Blade
Authors: Okita Yoji , Nita Kozo , Kubo Seiji 
Published: September 2016

The primary contribution of this research is to clarify the aerodynamic performance of a novel lightweight turbine blade with internal cooling passage and external film cooling, which is invented aiming at drastic weight reduction of a cooled blade. With a considerably thinner airfoil, a significant separation region is formed along the pressure side, and therefore aerodynamic performance with such a flow field should be investigated.
First, the lightweight cooled airfoil is designed. In the design process, a conventional thick airfoil is first defined as a baseline. With the baseline airfoil, only the mid and rear part of pressure side profile is redesigned to thin the airfoil without any change in the suction side geometry. The airfoil geometry is optimized so as not to bring significant aerodynamic loss increase. In this numerical optimization, the airfoil shape is gradually changed and evaluated step by step. In every step, an adjoint variable method is used to seek better airfoil shape, and then the generated new shape is evaluated with full RANS calculation. This iteration is repeated until any further recognizable weight reduction cannot be obtained without sensitive pressure loss increase and/or the airfoil shape reaches some geometrical constraints. The resultant optimized airfoil is approximately 20% lighter than the baseline hollow airfoil without any noticeable change in aerodynamic loss in the numerical solution.
Next, the optimized airfoil is tested in a high speed linear cascade rig to verify its aerodynamic performance. The baseline airfoil is also tested for comparison. The rig is composed of six airfoil passages. The compressed air is supplied to the cascade and discharges to the atmospheric exhaust chamber. The air is also heated up to about 540 K upstream of the cascade. The cascade exit Mach number at the design point is 1.25, while in the experiment other several off-design conditions are also tested to check if there is any Mach number sensitivity. At the design point, the optimized lightweight airfoil shows less total pressure loss compared to the baseline airfoil. Also, at any other off-design Mach number conditions tested, the magnitude of the pressure loss is less with the lightweight airfoil. These results verify that the proposed airfoil does not only bring a considerable weight advantage but also compares favorably with the conventional airfoil in aerodynamic performance.
Application of Latest Gas Turbine Technologies and Verification Results
Authors: Nishimura Yoshiaki , Sugawara Tomoyuki , Tada Kazuyuki , Masada Junichiro , Ai Toshishige , Iwasaki Tatsuya 
Published: September 2016

Utility companies and gas turbine manufacturer alike are working diligently to improve Gas Turbine Combined Cycle (GTCC) efficiency in order to reduce fossil fuel consumption as well as CO2 emissions.
Tohoku Electric Power Co., Inc. started operating large size GTCC in 1984 with Mitsubishi D series gas turbines. Since then, the company has lead the application of first of class Mitsubishi gas turbines. The company applied the first M701G gas turbine in 1999 and this successful experience was followed in 2010 with the single-shaft Sendai GTCC featuring the first M701F4.
The M701F5 was introduced in 2011 by Mitsubishi Hitachi Power Systems, LTD. (MHPS) and Tohoku Electric pioneered one more time its application at the No.3 Shin-Sendai Power Plant in 2015.
The M701F5 features the combination of technologies verified in other gas turbine frames. This paper introduces the feature of the M701F5 gas turbine including its technologies and verification results.
Improving the Efficiency of Heavy-Fuelled Gas Turbines: The Successful Experience Achieved at the Yugadanavi 300 MW CCGT in Sri Lanka
Authors: Marikkar Nuhuman , Vierling Matthieu , Aboujaib Maher , Sokolov Dmitry , Monetti Bruno , Russell Robert , Meskers Donald , Verdy Christophe , Moliere Michel 
Published: September 2016

An important asset of heavy duty gas turbines (“GT”) is their ability to burn a large variety of hydrocarbons, including low grade ones such as ash-forming fuels, in a well-controlled manner while achieving fairly high energy conversion efficiency.
In fact, there is still a considerable margin for improving the efficiency of gas turbines burning ash forming fuels if one succeeds in reducing the deposition of the ash in the turbine section which represents however a challenging technology lock.
The main difficulty for achieving this ambitious objective lies in the additional fouling entailed by the “inhibition process”. Indeed a magnesium-based corrosion inhibitor is injected into the GT combustors in order to suppress the corrosion threat placed by the highly fusible vanadium species coming from the fuel. This additive represents a substantial increase in the amount of ash crossing the machine whereby substantially accentuating the fouling of the hot gas path parts.
Within a joint initiative, LTL Holdings Ltd, GE Power & Water and the UTBM University have successfully tested a novel family of vanadium inhibitors called “bimetallic inhibitors” that combines magnesium and iron and lead to a considerable reduction in ash deposition while keeping intact the anti-corrosion protection. This new inhibitor family brings a decisive improvement in GT efficiency as well as a significant increase in plant availability. Indeed it enables reducing the frequency of the machine shutdowns that are periodically required to remove the ash deposits through water wash. In addition, iron procures an interesting soot suppression effect.
The paper outlines the development carried out in this project and sets out the successful field test performed in 2015 at the Yugadanavi 300 MW power plant in Sri Lanka.
Flow Analysis of a High Flowrate Centrifugal Compressor Stage and Comparison With Test Rig Data
Authors: Weber Anton , Morsbach Christian , Kügeler Edmund , Rube Christoph , Wedeking Matthias 
Published: September 2016

The flow field inside a single-stage centrifugal compressor characterized by a high flowrate of Φ = 0.15 and a design total pressure ratio of approximately 1.4 is analysed numerically. The stage geometry consists of a radially oriented inlet duct with uniform inflow without swirl, a 90 deg inlet bend in front of the impeller, the shrouded impeller itself followed by a large radial vaneless diffuser, a 180 deg U-turn, a radially oriented turning vane, a subsequent 90 deg bend, and as the last item a long axial exit duct. The impeller blades have large fillets at hub and tip and thick blunt trailing edges. Due to the rotating shroud, a labyrinth seal is placed above the impeller with 5 seal tips. The complete leakage region is also included in the CFD analysis. The blade numbers for the impeller and vane are 15 and 14, respectively. The test rig has recently been built at the Institute of Propulsion and Turbomachinery at RWTH Aachen University (Germany).
The first part of the CFD work presented was carried out before the first experimental data were available. Using the k-ω turbulence model of Wilcox (1988), a number of principal steady RANS calculations were performed to investigate the following: Impact of near wall grid resolution and turbulence model wall boundary condition treatment, impact of impeller fillets, and the influence of leakage flow. This part is completed by a comparison of steady RANS simulations with the time-mean results of unsteady RANS analyses of one blade passage. For the calculations presented in the second part, experimental data are available at the inflow and outflow planes. At these planes overall mean values were deduced. Additionally, 3- and 5-hole probe data are available at spanwise traverse planes located at the zenith of the U-turn and in the exit plane. For part two a finer grid with y+ values of approximately unity for all solid walls was used. In addition to the Wilcox k-ω model and the Menter SST k-ω model, two higher level turbulence models — the explicit algebraic Reynolds stress model Hellsten EARSM k-ω and the differential Reynolds stress model SSG/LRR-ω — have been tested and compared with the experiments. The agreement in terms of overall performance (total pressure ratio, isentropic efficiency) is satisfactory for all turbulence models used, but there are some differences: the k-ω model is shown to be the most stable one towards stall. On the other hand, it is shown that details of the flow field in terms of the two spanwise traverses can be better represented by the more advanced turbulence models. All CFD simulations have been performed at 100% shaft speed.
Multi-Objective Optimization of the Impingement-Film Cooling Structure of a HPT Endwall Using Conjugate Heat Transfer CFD
Authors: Chi Zhongran , Liu Haiqing , Zang Shusheng 
Published: September 2016

This paper discusses the approach of cooling design optimization of a HPT endwall with 3D Conjugate Heat Transfer (CHT) CFD applied. This study involved the optimization of the spacing of impingement jet array and the exit width of shaped holes, which were different for each cooling cavity. The optimization objectives were to reduce the wall temperature level and also to increase the aerodynamic performance of the gas turbine.
The optimization methodology consisted of an in-house parametric design & CFD mesh generation tool, a CHT CFD solver, a database of wall temperature distributions, a metamodel, and a genetic algorithm (GA) for evolutionary multi-objective optimization. The CFD tool was validated against experimental data of an endwall at CHT conditions. The metamodel, which could efficiently predict the aerodynamic loss and the wall temperature distribution of a new individual based on the database, was developed and coupled with Non-dominated Sorting Genetic Algorithm II (NSGA-II) to accelerate the optimization process.
Through optimization search, the Pareto front of the problem was found costing only tens of CFD runs. By comparing with additional CFD results, it was demonstrated that the design variables in the Pareto front successfully reached the optimal values. The optimal spacing of each impingement array was decided accommodating the local thermal load while avoiding jet lift-off of film coolant. It was also suggested that using cylindrical film holes near throat could benefit both aerodynamics and cooling.
A Single Formulation for Uncertainty Propagation in Turbomachinery: SAMBA PC
Authors: Ahlfeld Richard , Montomoli Francesco 
Published: September 2016

This work newly proposes an uncertainty quantification method named SAMBA PC (Sparse Approximation of Moment-Based Arbitrary Polynomial Chaos) that offers a single solution to many current problems in turbomachinery applications. At the moment every specific case is characterized by a variety of different input types such as histograms (from experimental data), normal PDFs (design rules) or fat tailed PDFs (for rare events). Thus, the application of UQ requires the adaptation of ad hoc methods for each individual case. A second problem is that parametric PDFs have to be determined for all inputs. This is difficult if only few samples are available. In gas turbines, however, the collection of statistical information is difficult, expensive and having scarce information is the norm. A third critical limitation is that if using Non-Intrusive Polynomial Chaos methods the number of required simulations grows exponentially with increasing numbers of input uncertainties: the so-called ‘curse of dimensionality’.
In this work it is shown that the fitting of parametric PDFs to small data sets can lead to large bias and the direct use of the available data is more accurate. This is done by propagating uncertainty through several test functions and the CFD simulation of a diffuser, highlighting the impact of different PDF fittings on the output. From the results it is concluded that the direct propagation of the experimental data set is preferable to the fit of parametric distributions if data is scarce. Thus, the suggested method offers an alternative to the maximum entropy theorem to handle scarce data.
SAMBA simplifies the mathematical procedure for many different input types by basing the polynomial expansion on moments. Its moment-based expansion automatically takes care of arbitrary combinations of different input data.
SAMBA is also numerically efficient compared to other UQ implementations. The relationship between the number of random variables and number of simulation is linear (only 21 simulations for 10 input random variables are required). It is shown that SAMBA’s algorithm can propagate a high number of input distributions through a set of nonlinear analytic test functions. Doing this the code needs a very small number of simulations and preserves a 5% error margin. SAMBA’s flexibility to handle different forms of input distributions and a high number of input variables is shown on a low pressure turbine blade based on H2 profile. The relative importance of manufacturing errors in different location of the blade is analyzed.
Uncertainty Quantification of Heat Transfer for a Highly Loaded Gas Turbine Blade Endwall Using Polynomial Chaos
Authors: Zhu Peiyuan , Yan Yong , Song Liming , Li Jun , Feng Zhenping 
Published: September 2016

The durability of highly loaded gas turbine blade is significantly impacted by high heat transfer. The heat transfer performance of the gas turbine endwall can be varied significantly due to the impacts of uncertainties in the manufacturing process and operation conditions. In this work, an uncertainty quantification (UQ) method is proposed by integrating generalized polynomial chaos expansions, non-intrusive spectral projection and Smolyak sparse grids. Then coupled with three dimensional (3D) Reynolds-Averaged Navier-Stokes (RANS) solutions, an uncertainty quantification procedure is carried out for heat transfer performance of highly loaded blade endwall. Wherein, the effects of the variation of geometric parameters and operation conditions are taken into account.
Specifically, the endwall heat transfer performance of a typical highly loaded turbine blade named Pack-B is numerically investigated. The turbulence intensity Tuinlet and Reynolds number Reinlet of inlet flow are considered as flow condition uncertainty parameters. As geometrical uncertainty parameters, the radius r and minimum angle α of blade root fillet are considered. These uncertainty factors have important influence on the secondary flow structure, resulting in significant variation of heat transfer performance of the endwall. Non-intrusive Polynomial Chaos (NIPC) is used to build a surrogate to reduce the quantity of the time consuming CFD simulation. A total of 137 sparse-grid-based design-of-experiment computations were carried out to build the high-fidelity surrogate. Using above method, the probability density function of the Nusselt number ( Nu ) of the endwall is obtained. The overall variation of Nu can be more than 10% due to the effect of the uncertainty factors. Finally, the sensitivity analysis shows that Reinlet has the most important influence on heat transfer performance of the whole endwall and other uncertainty factors also have significant effect on heat transfer performance at some local regions of the endwall such as wake region and middle part of blade passage.
Unsteady CFD Investigation of Effusion Cooling Process in a Lean Burn Aero-Engine Combustor
Authors: Mazzei L. , Picchi A. , Andreini A. , Facchini B. , Vitale I. 
Published: September 2016

The use of lean burning flames stabilized by highly swirling flows represents the most effective technology to limit NOx emissions in modern aeroengine combustors. In these devices up to 70% of compressed air is admitted in the combustor through the injection system, which is usually designed to give strong swirling components to air flow. Complex fluidynamics is observed with large flow recirculations due to vortex breakdown and precessing vortex core, that may result in a not trivial interaction with liner cooling flows close to combustor walls. This interaction and its effects on the local cooling performance make the design of the cooling systems very challenging and time-consuming, considering design and commission of new test rigs for detailed analysis. Keeping in mind costs and complexities related to the investigation of swirl flow/wall cooling interaction by experimental approach, CFD can be considered an accurate and reliable alternative to understand the associated phenomena. The widely known overcomes of RANS formulation (e.g. underestimation of mixing and inability to properly describe swirling flows) and the more and more impressive increase in computational resources, pushed hybrid RANS-LES models as valuable and affordable approaches to accurately solve the main turbulent flow structures.
This work describes the main findings of a CFD analysis intended to accurately investigate the flow field and wall heat transfer as a result of the mutual interaction between a highly swirling flow generated by a lean burn nozzle and a slot-effusion liner cooling system. In order to overcome some limitations of RANS approach, the simulations were performed with SST-SAS, a hybrid RANS-LES model. Moreover, the significant computational effort due to the presence of more than 600 effusion holes was limited exploiting two different modelling strategies: a homogeneous model based on the application of uniform boundary conditions on both aspiration and injection sides, and another solution that provides a coolant injection through point mass sources within a single cell. CFD findings were compared to experimental results coming from an investigation carried out on a three sector linear rig. The comparison pointed out that advanced modelling strategies, i.e. based on discrete mass sources, are able to reproduce the effects of mainstream-coolant interactions on convective heat loads. Validated the approach through a benchmark against time-averaged quantities, the transient data acquired were examined in order to better understand the unsteady behaviour of the thermal load through a statistical analysis, providing useful information with a design perspective.
Direct Coupling of a Two-Dimensional Fan Model in a Turbofan Engine Performance Simulation
Authors: Templalexis Ioannis , Alexiou Alexios , Pachidis Vassilios , Roumeliotis Ioannis , Aretakis Nikolaos 
Published: September 2016

Coupling of high fidelity component calculations with overall engine performance simulations (zooming) can provide more accurate physics and geometry based estimates of component performance. Such a simulation strategy offers the ability to study complex phenomena and their effects on engine performance and enables component design changes to be studied at engine system level. Additionally, component interaction effects can be better captured. Overall, this approach can reduce the need for testing and the engine development time and cost.
Different coupling methods and tools have been proposed and developed over the years ranging from integrating the results of the high fidelity code through conventional performance component maps to fully-integrated three-dimensional CFD models.
The present paper deals with the direct integration of an in-house two-dimensional (through flow) streamline curvature code (SOCRATES) in a commercial engine performance simulation environment (PROOSIS) with the aim to establish the necessary coupling methodology that will allow future advanced studies to be performed (e.g. engine condition diagnosis, design optimization, mission analysis, distorted flow).
A notional two-shaft turbofan model typical for light business jets and trainer aircraft is initially created using components with conventional map-defined performance. Next, a derivative model is produced where the fan component is replaced with one that integrates the high fidelity code. For both cases, an operating line is simulated at sea-level static take-off conditions and their performances are compared.
Finally, the versatility of the approach is further demonstrated through a parametric study of various fan design parameters for a better thermodynamic matching with the driving turbine at design point operation.
The Development of a Low Specific Speed Centrifugal Compressor Research Facility
Authors: Methel Jeanne , Gooding William J. , Fabian John C. , Key Nicole L. , Whitlock Mark 
Published: September 2016

To achieve aggressive specific fuel consumption goals, aircraft engines are tending toward higher overall pressure ratios and higher bypass ratios for turbofans. As sizes decrease to meet these requirements, centrifugal compressors become a viable option as the last stage of the high pressure compressor. The last stages of an axial compressor in a small core engine face reduced efficiency due to the relatively large tip clearances with respect to blade height, and therefore, it may be more appropriate to finish the final compression stage with a low specific speed centrifugal compressor.
A new facility, the Centrifugal STage for Aerodynamics Research (CSTAR) Facility, has been developed at Purdue University in cooperation with Rolls-Royce to gain further understanding of the complex aerodynamics found in such centrifugal compressors. The experimental data acquired in this facility will be utilized to develop and validate design tools for centrifugal compressors used in axial-centrifugal high-pressure compressors. The facility models the last (centrifugal) stage of an axial-centrifugal compressor and operates at engine-representative Mach numbers. In this paper, the facility is described in detail, and the baseline steady-state performance of the compressor is presented.
Theoretical and Numerical Analysis on the Temperature Drop and Power Consumption of a Pre-Swirl System
Authors: Liu Gaowen , Wu Heng , Feng Qing , Liu Songling 
Published: September 2016

As a component of delivering cooling air to turbine rotor blade at appropriate pressure, temperature and mass flow rate, pre-swirl system is very important to the cooling of turbine blades. It is attractive to the designers and scholars for its potential ability to reduce relative total temperature of cooling air as large as 100K. A pre-swirl system is actually an aero-thermodynamic system with energy transformation between work and heat. Theoretical analysis was carried out on an isentropic pre-swirl system to deduce equations for ideal temperature drop and power consumption. For an actual pre-swirl system, correlation between the actual temperature drop and power consumption was deduced, and a temperature drop effectiveness was defined also. Theoretical analysis shows that the system’s temperature drop increases linearly with the reduction of the power consumption.
Numerical models were derived from a real engine pre-swirl system with small simplification. Standard k-ε turbulence model and Frozen-Rotor approach were applied in the three dimensional steady simulations. Inlet total pressure and total temperature, outlet static pressure, mass flow rate delivered to the blade and rotating speed of rotor were kept to be fixed for all the models. The influences of heat transfer and sealing flow coming from the inner seal were ignored in the simulations. Section averaged parameters like pressure, swirl ratio and total enthalpy were presented at each typical station throughout the flow path. The relationship between the temperature drop and the power consumption of all the models has been verified to be consistent with the deduced formula. For the pre-swirl system with low radial location of nozzle, these measures, such as adding impellers in the cover-plate cavity and inclining the receiver hole, were taken to reduce the power consumption and enlarge the temperature drop obviously. For this specific pre-swirl system, models with high radial location of nozzle are more recommended to decrease the loss caused by the large circumferential velocity difference between the airflow and the rotor.