bluuebunny/crossref_metadata_2025_split huggingface dataset:
Comparison of Non-Linear and Linearized CFD Analysis of the Stator-Rotor Interaction of a Compressor Stage
Authors: Schoenenborn Harald , Ashcroft Graham 
Published: September 2014

The prediction of resonance amplitudes due to stator-rotor interactions is still an important task within the design process of turbomachinery bladings.
In this paper the stator-rotor interaction of a compressor stage which consists of an inlet guide vane and a rotor blade is studied with a non-linear and a linearized CFD code. First, a quasi-3D-study of a section close to the tip region is considered. The passing of the wake of the inlet guide vane over the rotor is studied for six different vibration mode shapes of increasing complexity (first bending mode up to 4th chordwise bending mode).
Whereas for low rotor speeds the comparison between linearized and non-linear calculations is quite good, large differences are found for high rotor speeds. It is shown that an acoustic interaction between the two stages with a cut-on mode is the cause for the large differences, leading to much higher unsteady pressure amplitudes on the rotor blade. This in turn leads to different aerodynamic work on the rotor blade for the different mode shapes.
The extension of the investigations to 3D shows essentially the same effects.
Experimental and Numerical Analysis of a Micro Plasma Actuator for Active Flow Control in Turbomachinery
Authors: De Giorgi Maria Grazia , Pescini Elisa , Marra Fedele , Ficarella Antonio 
Published: September 2014

Nowadays several active flow control systems, particularly dielectric barrier discharge plasma actuators, appear to be effective for the control of flow stream separation and to improve performance of turbomachinery. However these applications require high actuation strength, higher than the one generated by conventional macro plasma actuators. Research is actually improving the design of plasma actuator in order to enhance the flow control capability and reduce the power consumption.
In this contest, this work concerns the implementation of a micro plasma actuator for the active control in a compressor cascade. For this aim, firstly the micro actuator was developed and an experimental characterization of the flow induced by the device was done. The induced flow field was studied by means of Particle Image Velocimetry and Laser Doppler Velocimetry. The dissipated power was also evaluated. Experimental results were used to validate a multi-physics numerical model for the prediction of the body forces induced by the plasma actuator.
Finally, the obtained body force field was used for modeling the separation control by means of the micro plasma actuator in a highly-loaded subsonic compressor stator.
Aerodynamic Performance of Advanced Axial Flow Fan for Power Industry Within its Operational Range
Authors: Cyrus V. , Cyrus J. , Wurst P. , Panek P. 
Published: September 2014

The investigated axial flow fan investigated in our paper consisted of an advanced axial flow stage, an inlet chamber and a diffuser. The fan stage with high aerodynamic loading and the hub/tip ratio of 0.6 had the design flow and pressure coefficients of 0.60 and 0.83, respectively. The test and computed CFD aerodynamic performance of the axial flow fan and the fan’s stage were compared, with acceptable results. Subsequently, analysis of the computed 3D flow was carried out within the wide working range at the rotor blades stagger angle variation of ±20°.Consequence of the rotor blades adjustment is that the blade elements work often at the off-design working conditions with the flow separation on the blades suction and pressure sides. The flow is strictly three-dimensional.
Velocity profile distortion and swirl due to the flow separation in the stator blade row decreases the diffuser pressure recovery and efficiency. The diffuser in the axial flow fan environment achieves a significantly higher efficiency in comparison with conical diffuser furnished with ducted-flow inlet conditions due to the increased turbulent mixing.
Inlet chamber loss coefficient slightly decreased with the increasing flow rates due to the Reynolds number effect. Core flow in the inlet chamber is without occurrence of significant vortex inducing motion with the exception of the area near the tube where the fan’s shaft is located.
Alstom Gas Turbine Technology Overview/Status 2013
Authors: Kappis W. , Florjancic S. , Marchmont C. , Freitag E. 
Published: September 2014

Market requirements for the gas turbine business have significantly changed in the last years due to a stronger demand for lifecycle cost optimization and the increased share of renewable energy. Gas turbine technology development focus must be adapted accordingly. The need for increased efficiency throughout the operation range, particularly at part load, requires more accurate and faster design methods and prediction capabilities. At the same time, technologies must be developed and validated to increased flexibility in many areas, including unlimited operation range (without aerodynamic, mechanical or emission constraints), fuel types and composition, and faster ramp up rates (despite the increased thermal stress to gas turbine components) to stabilize the grid and to compensate for intermittent renewable power generation. Further lifecycle optimization counts on new technologies in reconditioning, lifetime monitoring and improved lifetime prediction.
This paper provides an overview of the recent research and development activities, the approach to bring them into a product and the resulting trend in Alstom gas turbine technologies.
Parametrical Diagnostics of Gas Turbine Performance on Site at Gas Pumping Plants Based on Standard Measurements
Authors: Komarov Oleg V. , Sedunin Viacheslav A. , Blinov Vitaly L. , Skorochodov Alexander V. 
Published: September 2014

The operation and maintenance of gas pumping units at the Gazprom transport systems are carried according to the current number of equivalent working hours of the gas turbine and the centrifugal natural gas compressor. Modern concepts of lean production requires maintenance procedures are to be done according to the current technical operating performance of units and its parametrical diagnostics. To meet these requirements an appropriate research project is ongoing at Ural Federal University. In this article a methodology for the technical performance estimation of GTU’s is proposed, verified and discussed. The method is based on processing of data gathered from standard thermodynamic measurements and therefore is applicable in the frame of most gas turbine units without major modifications.
The method includes a verified high-order mathematical model based on the Gas dynamic function for the precise analytical description of turbomachinery aerodynamics. A correction factor is introduced for adjusting the mathematical model in case of a non-traditional (not optimised) design applied in the exact turbine design.
Models are defined for different types of multi-shaft GT’s and an automated algorithm for calculation of the coefficients of technical performance of the overall unit is provided. A series of experiments showed convergence between traditional and new methods in effective power output and efficiency of units does not exceed 2%. Special software is designed for online monitoring of technical performance.
Heat Transfer Enhancement due to Coolant Extraction on the Cold Side of Effusion Cooling Plates
Authors: Da Soghe R. , Andreini A. , Facchini B. , Mazzei L. 
Published: September 2014

Effusion cooling represents one the most innovative technique to limit and control the metal temperature of aero-engine combustors liner and, recently, attention has been paid by the scientific community on the characterization and the definition of design practices of such devices. Most of these studies were focused on the heat transfer on the hot side of effusion cooling plates while just few contributions deal with the effusion plates cold side convective cooling. This paper reports a numerical survey aimed at the characterization of the convective cooling at the effusion plates cold side. Several effusion holes spacing are accounted for in conjunction with representative operating conditions.
The study led to the development of an empirical correlation for the prediction of the cold side heat transfer coefficient enhancement factor EF: it expresses the EF related to each extraction hole as a function of the pressure ratio β and the effusion plate porosity factor.
On the Prediction and Theory of the Temperature Increase of Low Pressure Last Stage Moving Blades During Low Volume Flow Conditions, and Limiting it Through Steam Extraction Methods
Authors: Beevers Adam , Havakechian Said , Megerle Benjamin 
Published: September 2014

During extreme low volume flow conditions, the last stages of a low pressure steam turbine operate in ventilation conditions that can cause a significant temperature increase of critical regions of the last stage moving blade. Under some conditions, the blade temperature may rise above a safe operating temperature, requiring the machine to be shut down. Limiting the heating effect on the last stage moving blade increases the allowable operating range of the low pressure turbine. One common method is to spray water droplets into the low pressure exhaust. As the length of last stage moving blades continues to increase, this method reaches its limit of practical operating effectiveness due to the amount of water required and its impact on the erosion of the LSB.
An investigation into complimentary solutions to limit the temperature increase was conducted using CFD. An appropriate CFD setup was chosen from a sensitivity study on the effect of geometry, mesh density, turbulence model and time dependency. The CFD results were verified against steam turbine data from a test facility. The proposed complimentary solutions to limit the temperature increase include low temperature steam extraction, targeted for critical regions of the moving blade. From the test turbine and CFD results, the drivers of the temperature increase during ventilation conditions are identified and described.
Numerical Investigation on the Heat Transfer Enhancement due to Coolant Extraction on the Cold Side of Film Cooling Holes
Authors: Andreini A. , Caciolli G. , Da Soghe R. , Facchini B. , Mazzei L. 
Published: September 2014

Film cooling represents one the most widely-used cooling techniques for hot gas path components. In particular, effusion cooling has recently become an important focus of attention in the context of aero-engine design due to its high cooling performance. Notwithstanding the huge amount of work dedicated to the heat transfer on the hot side of effusion cooling plates, it has been demonstrated that up to 30 % of the total cooling effectiveness of a typical effusion cooling configuration can be ascribed to cold side convective cooling. Nevertheless, in open literature it is possible to notice a lack of knowledge as far as this topic is concerned.
This paper describes a numerical activity aimed at investigating the phenomenology of the heat transfer at the entrance of film cooling holes. First of all the accuracy of the numerical approach has been validated through a comparison of enhancement factor measurements on a test case available in literature. Steady state RANS simulations have been performed, modeling turbulence by means of the k–ω SST model. The use of a transition model has been taken into account, since in these configurations the transitional behavior of the boundary layer has been highlighted in literature. Subsequently, the attention has been turned to the comprehension of the phenomena involved in the heat transfer augmentation, focusing the attention to the influence of fluid dynamic parameters such as suction ratio and Reynolds number. A good agreement has been highlighted with experimental data, therefore this work provides a starting point for future investigations on more representative configurations.
Impact of Swirl Flow on the Penetration Behaviour and Cooling Performance of a Starter Cooling Film in Modern Lean Operating Combustion Chambers
Authors: Wurm B. , Schulz A. , Bauer H.-J. , Gerendas M. 
Published: September 2014

An experimental and numerical study is presented that deals with the impact of the swirled hot gas main flow on the penetration behaviour and cooling performance of a starter cooling film.
Within modern combustion chambers designed for lean combustion the whole fuel/air mixing process is done by the fuel injectors without any additional mixing ports. Typically swirl stabilization is used within this kind of combustion chambers. The swirl flow interacts in a particular way with near wall cooling flows like starter cooling films which assure a proper wall cooling near the fuel injector. Experiments without combustion show the impact of the swirled main flow on the stability of the starter cooling film. Thermal analyses reveal a reduced cooling performance of the starter film near the stagnation area of the swirl flow. Laser optical measurement techniques reveal a significant reduced penetration of the starter cooling film close to the stagnation area. Numerical simulations show the reason for the reduced starter film performance in areas which cannot be accessed by optical measurement techniques. Based on experimental and numerical data different adaptive hole geometries where tested in combination with heat shield ribs in order to improve the starter film cooling performance. Results show that the combined application of heat shield ribs and adaptive cooling holes stabilize the starter cooling film and lead to a homogenous cooling performance.
Bi-Stable Flame Behaviour of Heavy Duty Gas Turbine Burner
Authors: Rofi Luca , Anisimov Vyacheslav , Chiarioni Aldo , Ozzano Claudia , Daccà Federico 
Published: September 2014

VeLoNOx™ (Very Low NOx) burners have been developed by Ansaldo Energia to satisfy the most restrictive emission limits of many countries. The stability field range is a key element for the design of such combustion systems; ever-deeper knowledge is therefore essential. The impact on stability of flame transition is of paramount relevance. Usually, flame transition occurs during load ramp: two different flame shapes take place in a well-defined load range. When loading up to base load condition, stability requires proper choice of flame shape. Observation of flame transition in a full-scale pressure test-rig implies a) unambiguous observation of an alteration in the flame shape b) measurement of both the burner area discharge coefficient “Alfa” (on the air side) and of a temperature drop on the walls of the combustion chamber.
The aim of the present work was to verify that RANS simulations with particular setting of the physical models can provide us with realistic description of the global flame behaviour in the full-scale, pressurised test rig even during the crucial flame transition at partial base load. This aim was achieved. CFD RANS has led to two different solutions with different shape, just like in the experiment. The main global parameters of the combustion system undergo similar changes and with similar magnitude in CFD results and in the experiment. In particular, the burner discharge coefficient “Alfa” increases with flame transition from “open” to “closed” flame, while the combustion chamber wall temperature decreases with flame transition from “open” to “closed” flame. It means that this CFD RANS simulation provides us with a reliable flow and temperature fields which can be used as meaningful input data for the more detailed analysis of both thermal load at combustion chamber wall and CO and NOx emission level, thermo-acoustic behaviour of the combustion system by means of more specific tools. Such information could be useful when designing more efficient, less polluting combustion systems.
Combustion Analysis in a Micro-Gas Turbine Supplied With Bio-Fuels
Authors: Cameretti Maria Cristina , Tuccillo Raffaele 
Published: September 2014

The authors examine in this paper the response of a micro gas turbine (MGT) combustor when supplied with gaseous fuels from biomass treatment or solid waste pyrolysis. Actually, a sort of off-design operation is induced by the employment of low calorific value fuels both in the combustor and in the whole micro turbine system. The objective is to optimize the combustor behaviour under the point of view of combustion efficiency and pollutant control.
To this aim, several solutions are experienced for a combustor fuelled with low LHV gaseous fuels derived from biomasses or solid waste treatment. An external EGR option is also considered as activated. The combustion development is analyzed by a combined approach based on the partially stirred reactor hypothesis and on the flamelet concept within a CFD simulation workbench.
Performance of a Finned Turbine Rim Seal
Authors: Sangan Carl M. , Scobie James A. , Owen J. Michael , Lock Gary D. , Tham Kok Mun , Laurello Vincent P. 
Published: September 2014

In gas turbines, rim seals are fitted at the periphery of the wheel-space between the turbine disc and its adjacent casing; their purpose is to reduce the ingress of hot mainstream gases. A superposed sealant flow, bled from the compressor, is used to purge the wheel-space or at least dilute the ingress to an acceptable level. The ingress is caused by the circumferential variation of pressure in the turbine annulus radially outward of the seal. Engine designers often use double rim seals where the variation in pressure is attenuated in the outer wheel-space between the two seals.
This paper describes experimental results from a research facility which models an axial turbine stage with engine-representative rim seals. The radial variation of CO2 gas concentration, swirl and pressure, in both the inner and outer wheel-space, are presented over a range of purge flow rates. The data are used to assess the performance of two seals: a datum double-rim seal and a derivative with a series of radial fins.
The concept behind the finned seal is that the radial fins increase the swirl in the outer wheel-space; measurements of swirl show the captive fluid between the fins rotate with near solid body rotation. The improved attenuation of the pressure asymmetry, which governs the ingress, results in an improved performance of the inner geometry of the seal. The fins also increased the pressure in the outer wheel-space and reduced the ingress though the outer geometry of the seal.
An Adjustment Method of Axial Force on Marine Multi-Shaft Gas Turbine Rotor
Authors: Wen Xue-You , Zhang Li-chao , Kou Dan , Xiao Dong-ming , Zhang Han 
Published: September 2014

During the research and development of marine multi-shaft gas turbine, the axial force on the thrust ball bearing of the rotor is required to be measured under actual operating conditions, and then the axial force would be adjusted to a predetermined range with a predetermined method, so as to assure the bearing’s long-term and reliable operation.
Basing on the theoretical analysis and engineering practice, we propose a practical method for the analysis and adjustment of the axial force. The method features combining the analysis of the air system and the small deviation analysis for the gas turbine engineering, with the typical experimental verifications.
According to this method and the first measurement results of the axial force, the adjustment measures, which would locate the axial force value in a predetermined range, can be given. Since the proposed adjustment measures are based on the theoretical analysis, the component tests and the actual measurement for the whole engine, the result is of engineering accuracy.
The engine delivery tests also show that the adjusting workload of axial force can be reduced significantly by use of the above method.
Blade Shape Optimization of Transonic Axial Flow Fan in Terms of Sectional Profiles and Stacking Line
Authors: Song Peng , Sun Jinju , Wang Ke 
Published: September 2014

Transonic axial flow fan has relatively high blade tip speed and produces higher pressure ratio than the subsonic. However, considerable losses are brought about by the shock waves close to blade tip and over part of span, leading to deteriorated overall efficiency and operating flow range. It is generally acknowledged that modifications of blade stacking line (axially sweep and tangentially lean) and sectional profiles can help to control spanwise distribution of blade loading, reduce shock loss and secondary flow, and extend the operating flow range.
The present study is to maximize the comprehensive benefits of simultaneously optimizing the sectional profiles and stack line by means of a global optimization method with reduced cost. In contrast with previous studies, it is of two distinguished features. First, in blade geometry parameterization, both sectional profiles and stacking line are varied to provide more flexible blade shape variation and subsequently permit more optimization performance gains. Secondly, with simultaneous variation of sectional profiles and stacking line, number of optimization variables and nonlinearity of optimization problem will increase largely. How to obtain a global optimal solution and also reduce the computation become the major concerns. For this purpose, a global optimization method proposed by us is used. It includes an improved CCEA (Cooperative Co-Evolution Algorithm) optimizer, adaptively updated kriging surrogate model, and one-stage Expected Improvement (EI) approach that permits adaptive sampling. At initial stage, a coarse surrogate model is constructed with small number of samples. During the optimization process, some new samples are identified, evaluated, and then used to refine the model and conduct further optimal searching. In the optimization process, the accuracy of the surrogate model is improved based on its own characteristics of optimization problem and this permits the optimizer to conduct the aim-oriented optimal searches. In such a manner, the surrogate model sustains high-level of accuracy while uses fewer samples, thus the blade optimization and computations are significantly reduced.
The optimization is conducted for NASA Rotor67 at design flow rate with a single workstation of DELL 7500. It is demonstrated that the optimized blade design produces significant performance gains at design condition (where the overall efficiency and pressure ratio are increased respectively by 1.27 and 6.53 points) and also at off-design conditions.