bluuebunny/crossref_metadata_2025_split huggingface dataset:
The Role of Rotor Welding Design in Meeting Future Market Requirements
Authors: Kern T.-U. , Almstedt H. , Thiemann Th. , Brussk S. , Niepold K. 
Published: November 2013

The demand for current and future steam turbine components is driven by higher efficiency but also by higher plant cycling needs and optimized cost balance. An increase in efficiency increases the demand for higher life steam temperatures of up to 620/630°C for today’s units and of even up to 720°C for future steam power plants. The gap between required material properties in the hot and cold running parts of a steam turbine rotor is widened by the increased live steam temperatures and the increased demand for flexibility and adaptability to current and expected future energy market conditions. Besides further material development, welding is one measure to realize such contradictory rotor characteristics. Whereas 720°C is more a future related task, solutions for 560°C / 620°C apply already welded rotors.
The paper discusses from a perspective of a steam turbine manufacturer the technical features to enable flexible high efficient rotor components with a focus on advanced welding technologies suitable for different large steam turbine components and what further steps for new welding technologies are under way.
Derivation of 2-D Empirical Correlations for Film-Cooling Effectiveness and Heat Transfer Augmentation From Spanwise Averaged Data and Correlations
Authors: Ingram Peter T. , Yavuzkurt Savas 
Published: November 2013

In existing gas turbine heat transfer literature, there are several correlations developed for the spanwise-averaged film-cooling effectiveness and heat transfer augmentation for inline injection on flat plates. More accurate and detailed predictions of film-cooling performance, particularly 3-D solid temperatures are needed for design purposes. 2-D correlations where effectiveness and heat transfer augmentation are functions of streamwise and spanwise directions are necessary to satisfy this need. Previously developed 2-D correlations for single row of cylindrical holes with inline injection have been improved to include the effects of shaped holes such as hole breakthrough width (t/D) and area ratio (AR). The correlations are improved to better match spanwise effectiveness of a single row of shaped cooling holes using data and spanwise-averaged correlations. Modifications to the correlations to improve application to compound injection (β) have been implemented. The blowing ratio is modified to account for the compound angle effect. The spanwise location of maximum film-cooling effectiveness and heat transfer augmentation are obtained as functions of the streamwise coordinate. Iterative Conjugate Heat Transfer Reduced Order Film Model (ICHT-ROFM) was used to obtain 3-D conjugate temperature distribution in film cooled solids.
The developed correlations predicted a relative cooling effect in the near hole region for shaped holes (24 K) and for compound angle injection (20K) compared to cylindrical holes. Spanwise variations in the solid temperature in the near hole region are between 40–50K for a temperature difference of 250K between the surface and the main stream and are quite significant, showing the need for 3-D simulations. Shaped and compound angle holes increase this temperature difference due to the increased cooling. The comparisons of solid temperatures for conjugate and non-conjugate heat transfer cases show about 13–18K or 8–10% of the local temperature difference of 180K. Therefore it can be concluded that the calculations of 3-D temperature distributions using conjugate heat transfer are very important for design purposes.
Progress of the 40MW-Class Advanced Humid Air Turbine Tests
Authors: Yagi Manabu , Araki Hidefumi , Tagawa Hisato , Koganezawa Tomomi , Myoren Chihiro , Takeda Takuya 
Published: November 2013

A 40MW-class test facility has been constructed to verify practicability of applying the advanced humid air turbine (AHAT) system to a heavy-duty gas turbine. Verification tests have been carried out from January 2012, and interaction effects between the key components were established.
First, water atomization cooling (WAC) was confirmed to contribute to both increased mass flow rate and pressure ratio for the axial flow compressor. The good agreement between measured and calculated temperatures at the compressor discharge was also confirmed. These results demonstrated the accuracy of the developed prediction model for the WAC.
Second, a control method which realized both flame stability and low NOx emissions was verified. Although the power output and air humidity were lower than the rated values, NOx concentration was about 10 ppm.
Finally, a hybrid nozzle cooling system, which utilized both compressor discharged air and humid air, was developed and tested. The metal surface temperatures of the first stage nozzles were measured, and they were kept under the permissible metal temperature. The measured temperatures on the metal surface reasonably corresponded with calculation results.
Suppression of Supersonic Jet Noise From Rectangular Nozzle by Microjet Injection: Influence of Main Jet Condition
Authors: Okada Ryuichi , Watanabe Toshinori , Uzawa Seiji , Himeno Takehiro , Oishi Tsutomu 
Published: November 2013

Jet noise reduction is essential for next-generation environmentally-friendly supersonic transport. In the present study, experimental and numerical investigations were performed to clarify the effect of microjet injection on supersonic jet noise and flow field. The experiments were focused on supersonic jet with Mach number up to 1.39, issuing from a rectangular nozzle with high aspect ratio.
The experiments varied several parameters including main nozzle pressure ratio, total pressure of microjet, number of microjets and microjet injection angle. Far-field sound pressure measurement was performed, and the characteristics of noise reduction, including its directivity, were investigated. On the other hand, the flow field was visualized with a Schlieren technique in order to understand the mechanism of noise reduction. The unsteady behavior of the shock structure and the shear layer were investigated based on the visualization results. To investigate the effect of microjets on the 3-dimensional flow field, steady RANS analysis of the flow field was performed under various conditions of the main jet and the microjets.
On the Selection of an Optimal Pattern Recognition Technique for Gas Turbine Diagnosis
Authors: Loboda Igor , Yepifanov Sergiy 
Published: November 2013

Efficiency of gas turbine monitoring systems primarily depends on the accuracy of employed algorithms, in particular, pattern recognition techniques to diagnose gas path faults. In investigations many techniques were applied to recognize gas path faults, but recommendations on selecting the best technique for real monitoring systems are still insufficient and often contradictory.
In our previous works, three recognition techniques were compared under different conditions of gas turbine diagnosis. The comparative analysis has shown that all these techniques yield practically the same accuracy for each comparison case.
The present contribution considers a new recognition technique, Probabilistic Neural Network (PNN), comparing it with the techniques previously examined. The results for all comparison cases show that the PNN is not practically inferior to the other techniques. With this inference, the recommendation is to choose the PNN for real monitoring systems because it has an important advantage of providing confidence estimation for every diagnostic decision made.
Influence of Non-Uniform OGV on High Pressure Compressor Performance
Authors: Yang Ping , Xie Weiliang , Xu Feng , Feng Jinzhang 
Published: November 2013

Generally, the outlet guide vanes (OGV) of a high pressure compressor (HPC) have a single vane profile and are placed uniformly circumferentially. However, in some situations, portions of the OGV are thickened to be accommodated to some special requirements which may result in negative influences on the HPC performance.
This paper describes the design of a non-uniform OGV row of a multi-stage HPC. The OGV is periodically composed of one thick vane and two thin vanes. A series of vanes are selected by changing vane geometry parameters including vane stagger and camber, location of maximum thickness, thickness distribution, chord length and vane circumference position. Numerical simulations of these different non-uniform OGV rows along with the same rotor upstream are carried out to evaluate the impact of these parameters on the non-uniform OGV performance. Through this “manual-iteration” process, the best configuration is selected as the final “optimized” design.
The results show that, firstly, it is beneficial to set the suction surface incidence angle of the thick airfoils the same with that of the thin airfoils for uniform incoming flow field; secondly, the divergence rate of passage should be carefully controlled to reduce the loss coefficient; thirdly, the vane circumference position should be adjusted to keep the mass flow of each passage being equal to ensure uniformity of the outlet flow field. Finally, it is demonstrated that after optimization, the adverse effects of the non-uniform OGV on the whole HPC performance can be nearly eliminated.
Turbine Endwall Film Cooling With Pressure Side Radial Holes
Authors: Zhang Yang , Yuan Xin 
Published: November 2013

A key technology of gas turbine performance improvement was the increase in the turbine inlet temperature, which brought high thermal loads to the nozzle guide vane (NGV) components. Strong pressure gradients in the NGVs and the complex secondary flow field had made thermal protection more challenging. As for the endwall surface near the side gill pressure region, the relatively higher local pressure and cross flow apparently decreased the film-cooling effectiveness. The aim of this investigation was to evaluate a new design, improving the film-cooling performance in a cooling blind area with radial cylindrical holes on the pressure side.
The test cascades model was manufactured according to the GE-E3 nozzle guide vane scaled model, with a scale ratio of 2.2. The experiment was performed under the inlet Mach number 0.1 and the Reynolds number 3.5×105 based on an axial chord length of 78 mm. Four rows of staggered radial film-cooling holes were placed at the pressure side gill region. The diameter of the cylindrical holes was 1 mm and the length was 5 d, with a hole space of 6 d. The spanwise angle of the cooling holes was 35 ° and the radial angle was 90 °. Three blowing ratios were chosen as the test conditions in the experiment, M = 0.7, M = 1.0 and M = 1.3. The film-cooling effectiveness was probed using PSP (pressure sensitive painting) technology and the post processing was performed by means of a mass and heat transfer analogy.
Through the investigation, the following results could be achieved: 1) the film-cooling effectiveness on the endwall surface near the pressure side gill region increased, with the highest parameter at X/Cax = 0.3; 2) a double-peak cooled region developed towards the suction side as the blowing ratio increased; 3) the advantage of the pressure side radial cooling holes was apparent on the endwall surface near the gill region, while the coolant film was obviously weakened along the axial chord at a low blowing ratio. The influence of the pressure film cooling could only be detected in the downstream area of the endwall at the higher blowing ratio.
Unsteady Aerodynamics of Low-Pressure Steam Turbines Operating Under Low Volume Flow
Authors: Megerle Benjamin , Rice Timothy Stephen , McBean Ivan , Ott Peter 
Published: November 2013

Non-synchronous excitation under low volume operation is a major risk to the mechanical integrity of last stage moving blades (LSMBs) in low-pressure (LP) steam turbines. These vibrations are often induced by a rotating aerodynamic instability similar to rotating stall in compressors. Currently extensive validation of new blade designs is required to clarify whether they are subjected to the risk of not admissible blade vibration. Such tests are usually performed at the end of a blade development project. If resonance occurs a costly redesign is required, which may also lead to a reduction of performance. It is therefore of great interest to be able to predict correctly the unsteady flow phenomena and their effects.
Detailed unsteady pressure measurements have been performed in a single stage model steam turbine operated with air under ventilation conditions. 3D CFD has been applied to simulate the unsteady flow in the air model turbine. It has been shown that the simulation reproduces well the characteristics of the phenomena observed in the tests. This methodology has been transferred to more realistic steam turbine multi stage environment. The numerical results have been validated with measurement data from a multi stage model LP steam turbine operated with steam. Measurement and numerical simulation show agreement with respect to the global flow field, the number of stall cells and the intensity of the rotating excitation mechanism. Furthermore, the air model turbine and model steam turbine numerical and measurement results are compared. It is demonstrated that the air model turbine is a suitable vehicle to investigate the unsteady effects found in a steam turbine.
Effect of Confinement on Combustion Characteristics in Lean Direct Injection Combustion System
Authors: Zeng Qinghua , Kong Wenjun , Sui Chunjie 
Published: November 2013

Confinement has direct influence on the dome reference velocity and indirect influence on the combustor’s performance, emissions, operability, liner and dome temperature levels and gradients. Understanding the effects of the confinement is crucial to conventional combustor design.
Recently, lean direct injection (LDI) combustor has been popularly employed to reduce nitrogen oxides (NOx) emissions from gas turbine. Compared to conventional combustor, LDI combustor has a much larger amount of air entering into the dome. Therefore, combustion characteristics and confinement effects in LDI combustor are quantitatively or even qualitatively different from those in conventional combustor. As a result, some design criteria for conventional combustor are no longer applicable for LDI combustor and it is essential to investigate the effects of confinement level in LDI combustor.
In the literature, several studies have been conducted to understand how the confinement levels affect the characters of swirling non-reactive flow. However, there are few studies on the reactive flow and thereby the effects of confinement on combustion characteristics are not well understood. Due to its important role in combustor design, the confinement effect on spray combustion in LDI mode is systematically investigated in the present study.
The experimental setup is established to study the confinement effects. Experimental data on flame characteristics, centerline temperature distribution, and pollutant emissions are obtained. Experiments at five different confinement ratios, 2.8, 6.8, 10.6, 19.5, and 28.5, are conducted. The results show that the confinement level has an important impact on the flame characteristics, centerline temperature, and pollution emissions. The optimal confinement ratio is determined, at which the pollution emissions become the lowest.
Mechanical Design of Large Steam Turbine Components for Part Load Conditions
Authors: Lückemeyer N. , Qin F. 
Published: November 2013

Recent developments like the significant introduction of renewable energy sources to the electricity networks worldwide have led to more frequent and extended operation of fossil power plants in part load conditions. As a result the typical load spectrum of large steam turbines used for electricity generation has changed over the last years and will continue to do so.
A number of papers has already been published on how to optimize the water-steam cycle and the steam turbine from a thermodynamical and aero-dynamical point of view for this new load regime in order to improve the average efficiency. But the changed load regime also poses a challenge for the mechanical design and structural integrity assessment of steam turbines.
Reason for this is that the rated conditions are not necessarily the most challenging boundary conditions and therefore not necessarily a suitable, conservative envelope for all other load cases for mechanical design. Pressures decrease, but steam temperatures in part loads can increase and heat transfer coefficients and the influence of radiation on the component temperatures change.
With an increasing demand for and a wider range of part load operation it for this reason becomes more important than ever to consider these load cases in the mechanical design.
This paper uses a large, double-flow intermediate pressure steam turbine as an example to investigate the impact of extended part load operation on the design. Both an analytical model and finite element calculations are used to compare from a structural integrity point of view a low part-load load case and the rated load case and to evaluate the significance of heat radiation.
Residence Time Distribution in a Swirling Flow at Non-Reacting, Reacting, and Steam-Diluted Conditions
Authors: Göckeler Katharina , Terhaar Steffen , Paschereit Christian Oliver 
Published: November 2013

Residence time distributions in a swirling, premixed combustor flow are determined by means of tracer experiments and a reactor network model. The measurements were conducted at non-reacting, reacting, and steam-diluted reacting conditions for steam contents of up to 30% of the air mass flow.
The tracer distribution was obtained from the light scattering of seeding particles employing the quantitative light sheet technique (QLS). At steady operating conditions, a positive step of particle feed was applied, yielding cumulative distribution functions (CDF) for the tracer response. The shape of the curve is characteristic for the local degree of mixedness. Fresh and recirculating gases were found to mix rapidly at non-reacting and highly steam diluted conditions, whereas mixing was more gradual at dry reacting conditions. The instantaneous mixing near the burner outlet is related to the presence of a large scale helical structure, which was suppressed at dry reacting conditions.
Zones of similar mixing time scales, such as the recirculation zones, are identified. The CDF curves in these zones are reproduced by a network model of plug flow and perfectly mixed flow reactors. Reactor residence times and inlet volume flow fractions obtained in this way provide data for kinetic network models.
Modelling of Deposit Mechanisms Around the Stator of a Gas Turbine
Authors: Birello Fabio , Borello Domenico , Venturini Paolo , Rispoli Franco 
Published: November 2013

The analysis of particle laden flow in turbines stages is a very actual topic as deposit can alter the blade cooling due to a partial or total blockage of film cooling holes and the modification of heat transfer coefficient between the internal cooling fluid and the blade surface.
A computational tool for predicting particle deposition on a solid surface, developed by the authors, is here applied and validated against literature data. The computational model is based on an Euler-Lagrangian approach with a one-way coupling for the description of the fluid-particles interaction. The deposit model used is based on the paper of Walsh et al., 1990.
The prediction of the fluid phase is carried out by using a URANS (Unsteady Reynolds Averaged Navier Stokes) approach on the well-validate open-source code OpenFOAM widely tested and validated by the authors and many other researchers worldwide in a number of turbomachinery relevant cases.
The numerical campaign was firstly focused on the analysis of the details of the flow field in order to identify the eventual presence and position of shocks as well as to put in evidence the shock/boundary layer interaction.
Then, the trajectories of two class of particles are analyzed in order to determine the influence of drag, pressure and velocity gradient on the particle pattern.
Finally, the adhesion on the blade surface and the influence of flow temperature is discussed.
An Integrated Assessment of an Organic Rankine Cycle Concept for Use in Onboard Aircraft Power Generation
Authors: Perullo Christopher A. , Mavris Dimitri N. , Fonseca Eduardo 
Published: November 2013

It is well established that there are advantages in moving towards non-pneumatic engine secondary systems. Such systems are used primarily to provide pressurization, cabin climate control, and de-icing; however, as bypass ratios continue to grow and engine cores become more efficient, the engine fan diameter is increased and core size is diminished. As a consequence, pneumatic off-takes require a larger percentage of the core flow leading to larger performance penalties. One current solution is to drive the aircraft environmental control systems (ECS) with large engine driven electric compressors rather than to use high pressure air from the core. Since cores are generally less sensitive to electrical power off-takes than to pneumatic off-takes this results in a smaller performance penalty. [F1] Using electrical air compressors also ensures fresh, clean air is delivered to the ECS thereby eliminating the risk of engine bleed contaminated cabin air.
This research uses the Environmental Design Space (EDS) to examine the feasibility of recovering engine core exhaust heat to perform useful work within the aircraft. EDS serves to capture interdependencies at the conceptual design level of fuel burn, emissions, and noise for conventional and advanced engine and airframe architectures [F2]. Recovering exhaust heat is accomplished through a novel concept that makes use of an organic Rankine cycle (ORC).The concept is similar in principle to heat recovery steam generators used in power plant applications to improve combined cycle efficiency [3]. The main difference is the ORC system is relatively lightweight and appropriate for use onboard an aircraft. The waste heat in this application is used to generate electricity to drive external air compressors to supply flow to the ECS. As a result pneumatic bleeds within the engine can be eliminated, thereby eliminating growing performance penalties associated with shrinking core size and increased fan diameters. An ORC is considered because ORC cycles are ideal for extracting low grade heat. As an additional benefit the ORC vapor cycle can use the fan inlet and wing leading edge anti-ice devices as a condensation heat transfer mechanism that could also allow the system to provide anti-icing capabilities, further reducing engine pneumatic off-takes. The current research focuses on the system as applied the ORC concept to a CFM56 sized engine and has analytically demonstrated from a 0.9% to a 2.5% benefit in vehicle fuel burn relative to a conventional, pneumatically driven ECS. Actual fuel burn savings are dependent on the net installation weight of the ORC cycle.