bluuebunny/crossref_metadata_2025_split huggingface dataset:
Accuracy Research on the Modeling Methods of the Gas Turbine Components Characteristics
Authors: Peng Shuhong , Sun Bo , Ying Yulong , Wu Keliang , He Lei , Xu Qiang 
Published: September 2014

In the process of a gas turbine performance simulation based on component characteristics, the accuracy description of components characteristics is a significant element which affects the accuracy of the results, especially for part-load and startup performance calculation.
For the traditional modeling method of components, the discrete characteristic maps was integrated into the thermodynamic model in the form of arrays, which present the relationships among IGV opening angle γ, speed, pressure ratio and flow/efficiency of compressor, as well as the relationships among speed, pressure ratio and flow/efficiency of turbine. It’s obvious that fine discrete grids are required in this traditional interpolating method to obtain enough data to reflect the original information accurately. However, the characteristic maps obtained are always sparse, which lead to considerable interpolation error.
With regard to poor accuracy of traditional component characteristics method, we integrate partial least square (PLS) method into reconstructing the components characteristic curves. It doesn’t need the discretization of component characteristic maps, and the reconstruction equation can be solved directly in the simulation process, which avoids the interpolation errors in the traditional processing methods of component characteristics.
The traditional method, BP artificial neural network, PLS of two variables and ternary PLS of three variables was implemented in performance simulation of the same gas turbine. The simulation results of components characteristics and gas turbine thermodynamic performance with different methods were compared with the known performance data of the gas turbine. And the calculation accuracies and their effects on overall performance were analyzed. The implement of PLS in component characteristics simulation could be useful for improving the accuracy of the gas turbine thermodynamic model, and could benefit for gas turbine power plant upgrades and technology improvement because thermodynamic mode is the base of on-line monitoring and fault diagnosis system.
Effect of Airfoil Clocking on Noise of LP Turbines: Part II — Modal Structure Analysis
Authors: Serrano Adolfo , Fernández José Ramón 
Published: September 2014

The clocking effect on noise is investigated experimentally in a multistage turbine high speed rig. It consists in a three stages state of the art Low Pressure Turbine (LPT). The work is a continuation of a first part in which efficiency and noise are addressed together for the same test [1]. Due to the large amount of data acquired in the experiment, noise results presented in [1] are based on averaged Sound Pressure Level (SPL) at the exit. The present paper goes beyond that analysis and aims to get the modal structure and its sensitivity to clocking.
Noise measurements are taken ‘in-duct’ immediately downstream the LPT by a continuously and slowly rotating device denominated Noise Measurement Module (NMM). Previous experimental studies [2] [3] demonstrate this as an effective way of characterizing the LPT noise source in an engine, provided that the necessary hot to cold conversions and propagation effects are included.
The rotation of the NMM allows the identification of the spinning modes responsible of the tone noise. The axial dependence acquired by the different sensors along the duct gives the radial structure of the spinning modes. The modal decomposition allows the estimation of the acoustic energy, which is the proper magnitude for observing the clocking dependence. The data reduction process from time history signals to the acoustic power estimation is described in detail. Special attention is paid on the applicability limits and uncertainty analysis.
Results from the first part [1] suggest that efficiency is weakly affected by clocking whereas noticeable influence of some tone noise is observed. The acoustic power and modal structure dependence of the same tones observed in [1] will allow the comprehension of the noise clocking mechanisms in future. Although this is out of the scope, results suggest some physical explanation described here.
Auto-Tuning of Real-Time Dynamic Gas Turbine Models
Authors: Panov V. 
Published: September 2014

Real-time gas turbine engine models are integral part of techniques such as model-based control and diagnostics. The use of model based techniques to diagnose and adaptively manage degradation of engine components is crucial for operational effectiveness of gas turbines. Since the gas turbine model represents “nominal” engine, it must be adapted or tuned to the performance of the real engine as it deviates from nominal baseline. Implementation of a method for auto-tuning of dynamic gas turbine engine models was considered in this paper, and a non-linear physics based component level model was facilitated as an on-line gas turbine model. Real-time nonlinear dynamic model of an industrial twin-shaft gas turbine with tracking filter was deployed onto the dedicated hardware platform and integrated with the engine control system.
In presented application the identified gas turbine health parameters were obtained by the performance estimation tool and included in the observer design. The designed observer detects changes in the engine health parameters and generates model tuners. The model tuning process based on Kalman filtering technique was applied to secure robust execution of real-time dynamic models.
Proposed auto-tuning methodology provides a tool for model adaptation, capable of addressing abrupt and gradual degradation of engine performance and at the same time offers a means for model compensation of performance deviation caused by engine-to-engine variation.
Although most of performance tracking and diagnostic methods are developed for gas turbine operating at steady state, current trend demonstrates increasing interest in diagnostics during transient operation. Devised method estimates dynamic behaviour of gas turbine health parameters enabling in that way performance tracking under transient conditions. Examples of model adaptation during gas turbine engine transient operation are given in the paper.
Rotating Stall Observations in a High Speed Compressor: Part 1 — Experimental Study
Authors: Dodds J. , Vahdati M. 
Published: September 2014

In this two part paper the phenomenon of part span rotating stall is studied. The objective is to improve understanding of the physics by which stable and persistent rotating stall occurs within high speed axial flow compressors. This phenomenon is studied both experimentally (part 1) and through the use of unsteady RANS simulations (part 2).
In this paper, the behaviour of an 8 stage high speed compressor is studied during slow acceleration manoeuvres along a fixed working line. Casing mounted pressure transducers and rotor mounted strain gauges are used to examine the spectral content of any unsteadiness in the flow and its behaviour across the operating range.
By deliberate aerodynamic mismatching of the front stages through adjustment of three rows of variable stator vanes, stable rotating stall is initiated. The observed behaviour falls into two ‘families’ of high and low frequency when tracked on the instrumentation. Further analysis based on the Doppler shift between the static and rotating measurements confirms that these respective phenomena are due to rotating stall of high and low cell count. Acoustic modes resulting from stall/rotor interaction are also identified.
Strong correlation of the stall intensity with simple 1D meanline predicted loading parameters suggests that these families of behaviour are independently linked to the stalling of different regions within the compressor.
Application of Planar Laser-Induced Phosphorescence to Investigate Jet-A Injection Into a Cross-Flow of Hot Air
Authors: Tan Zu Puayen , Lubarsky Eugene , Bibik Oleksandr , Shcherbik Dmitriy , Zinn Ben T. 
Published: September 2014

This paper describes the development of the Planar Laser-Induced Phosphorescence (PLIP) technique for mapping the fuel temperature and concentration distributions in a jet-in-cross-flow (JICF) spray study. The spray was produced by injecting cold liquid Jet-A into hot cross-flowing air. The application of PLIP required the seeding of liquid fuel with micron-size thermographic phosphor particles before injection. The resulting spray produced phosphorescence and droplets Mie-scattering signals when illuminated by a 355nm planar UV laser sheet of 0.054J/pulse energy. The technique was investigated as a potential alternative to the use of Jet-A Planar Laser-Induced Fluorescence (PLIF) for the mapping of fuel concentration in sprays, because the low signal intensity of Jet-A’s fluorescence at high T prevents the use of the PLIF approach. In contrast, PLIP provides a strong signal at high T, and allows the simultaneous determination of local T and fuel concentration when two spectral bands of the phosphorescence emission are imaged and their ratio-of-intensities (RI) determined. In addition, the locations where liquid fuel droplets exist were imaged from the UV Mie-scattering of the laser-sheet (which can also be done in PLIF).
In the present investigation, an optical system that imaged two spectral bands of phosphorescence and one wavelength of Mie-scattering was developed. It consisted of three CCD cameras with dichroic beam-splitters and interference narrow bandpass filters. The spray-pattern within a span of ∼80×30 orifice diameters was captured, with spatial resolution of about 0.1mm/px. The investigated jet-in-cross-flow spray was produced by injecting Jet-A fuel from a 0.671mm diameter orifice located on the wall of a rectangular channel (25.4×31.75mm cross-section). The cross-flow air was preheated to temperatures encountered in modern gas turbines (up to 480°C), while the temperature of the injected Jet-A fuel was in the T = 27–80°C range. YVO4:Eu phosphor particles with a median size of 1.8 microns were used to seed the fuel.
Since the emissions of the commonly used Dy:YAG thermographic phosphor were found to be too weak and had wavelengths that overlapped with Jet-A fluorescence signals, YVO4:Eu was used for the JICF studies instead. It was observed that while the emissions of YVO4:Eu were stronger than Dy:YAG, the range of T where it can be applied in the PLIP technique was more limited — just sufficient for the investigated JICF. Preliminary results from the study showed rapid changes in fuel concentration and T from the injector up to z/dinj∼30 for momentum ratios of J = 5, 10 and 20, followed by a more gradual mixing/heat-up downstream. It was also found that deposition of phosphor particles on channel-walls interfered with the spray characterization, reducing the accuracy of the measurements.
Combination of Active and Passive Flow Control in a High Speed Compressor Cascade
Authors: Liesner Karsten , Meyer Robert 
Published: September 2014

An experimental study is presented in which passive and active flow control are combined in a way that they complement and support one other. Secondary flow control using boundary layer fences is combined with a boundary layer suction in a compressor cascade at high Mach numbers. Inflow Mach number of 0.67 and Reynolds number (based on chord length) of 560.000 assure realistic conditions. The cascade, equipped with five stator vanes of NACA65 K48 type is used in an ambient condition measurement environment. Pressure measurements form the basis of the experimental investigations, flow visualization is used to obtain insight into the topology of the flow field.
The boundary layer fences installed on the suction side of the vanes create a region of low-loss two dimensional flow in the center of the passage. A region of high flow loss is generated at the side wall between wall and BL fence. This region is treated with through-wall boundary layer suction as used in previous investigations. This helps stabilize the flow near the wall and prevent large separated areas. The total pressure loss is reduced remarkably and the outflow becomes more two-dimensional compared to the reference measurement and even compared to the measurement with suction applied without BL fences. The application of boundary layer fences on flow-suction experiments allows obtaining the same loss reduction gains by using lower amounts of suction.
Experimental Testing of Carbon Brush Seals for Aero Engines Bearing Chambers
Authors: Outirba Bilal , Hendrick Patrick 
Published: September 2014

This paper provides the first step in sizing carbon brush seals for aero-engine oil bearing chambers applications.
Recent developments in the aeronautic domain focus strongly on the reduction of aero-engine specific oil consumption. For instance, optimizing the civil aircraft gas turbine engine lubrication oil system is considered as one of the main targets in this research. Specifically, brush seals have shown tremendous leakage performance in sealing secondary flows compared to classic labyrinth seals over the last few decades. Therefore, an attractive idea is to extent their utilization to oil bearing chamber applications.
To perform the experimental part of the study, a test rig has recently been built at ULB. This test rig will be described in this paper. A parametrical study has been performed in stationary conditions, and at very low rotation speed. A particular attention was given to the air consumption and the torque friction losses. Finally, a test simulating the effects of a rotor excursion on the brush seal performance has been made.
Development and Implementation of Alternative Repair Processes for Reconditioning of Fr7FA+e, 1st Stage Nozzles
Authors: Miglietti Warren , Summerside Ian 
Published: September 2014

The 60 Hz, Frame 7F engine has been in commercial operation for more than two decades now with approximately 800 Frame 7 (F, FA, FA+ and FA+e models) machines existing in North America and a total of over 1100 F-class machines throughout the world. Of importance to operators/users and owners of this gas turbine engine is the ability to not only recondition the turbine “hot-end section” components, in order to support maintenance requirements, but also to reduce the life cycle costs of these components.
Stage 1 nozzles are a cast doublet, manufactured from FSX-414 Co-based superalloy. There are 24 nozzles in an engine set. As a result of the extreme turbine inlet temperatures at the 1st stage nozzle, these components experience severe thermal fatigue cracking. On one particular OEM engine set inspected, over 600 cracks were identified on each nozzle after engine operation. As a consequence, the stage 1 nozzles when compared to the other components in the engine exhibits the worst degradation and is therefore a focus point of reconditioning for those in the industry.
The technical objective is to describe the development of a repair scheme for the stage 1 nozzle that can successfully address and repair this level of severe cracking and oxidation, with 0% scrap/fallout for a heavy repair, after a normal duty cycle. Special processes have been established for these components repairs, including but not limited to removal of the damaged and oxidized trailing edges by machining, high frequency Gas Tungsten Arc Welding (GTAW) of new trailing edge coupons.
This technical paper describes the repair process development and implementation of the different stages of the repair schemes and shows metallurgical and mechanical characteristics of the repaired regions of the component. As a result of successfully executing these special processes, although a heavy repair workscope was implemented; all the nozzles were successfully repaired without any scrap.
Scaling of Film Cooling Performance From Ambient to Engine Temperatures
Authors: Greiner Nathan J. , Polanka Marc D. , Rutledge James L. 
Published: September 2014

The present study employs Computational Fluid Dynamics (CFD) to explore the complexities of scaling film cooling performance measurements from ambient laboratory conditions to high temperature engine conditions. In this investigation, a single shaped hole is examined computationally at both engine and near ambient temperatures to understand the impact of temperature dependent properties on scaling film cooling performance. By varying select flow and thermal parameters for the low temperature cases and comparing the results to high temperature flow, the parameters which must be matched to scale film cooling performance are determined.
The results show that only matching the density and mass flux ratios is insufficient for scaling to high temperatures. In accordance with convective heat transfer fundamentals, freestream and coolant Reynolds numbers and Prandtl numbers must also be matched to obtain scalable results. By virtue of the Prandtl number for air remaining nearly constant with temperature, the Prandtl number at ambient conditions is sufficiently matched to engine temperatures. However, laboratory limitations can prevent matching both the freestream and coolant Reynolds numbers simultaneously.
By examining this trade-off, it is determined that matching the coolant Reynolds number produces the best scalability. It is also found that by averaging the adiabatic effectiveness of two experiments in which the freestream and coolant Reynolds number are matched respectively results in significantly better scalability for cases with a separated coolant jet.
Improvement of Flat-Plate Film Cooling Performance by Double Flow Control Devices: Part I — Investigations on Capability of a Base-Type Device
Authors: Funazaki Ken-ichi , Nakata Ryota , Kawabata Hirokazu , Tagawa Hisato , Horiuchi Yasuhiro 
Published: September 2014

This paper deals with effects of double flow control devices (DFCDs) on flat plate film cooling performance. Aiming for further improvement of film effectiveness of discrete cooling holes, this new type of controlling method is invented and recently patented by the authors. The performance of base-type DFCDs, installed just upstream of cooling holes with conventional round or fan-shaped exits, is thoroughly investigated and reported in this study. Effects of the hole pitch are examined. Three hole-pitch cases, 3.0d, 4.5 d and 6.0 d are examined in this study to explore a possibility of reducing the cooling air by the application of DFCDs, where d is a hole diameter. In order to investigate the film effectiveness, a transient method using a high-resolution infrared camera is adopted. At the downstream of the cooling hole, the time-averaged temperature field is captured by a thermocouple rake and the time-averaged velocity field is captured by 3D Laser Doppler Velocimeter (LDV), respectively. Furthermore, the aerodynamic loss characteristics of the cooling hole with and without DFCDs are measured by a total pressure probe rake. The experiments are carried out for two blowing ratios, 0.5 and 1.0. It is found that DFCDs are quite effective in increasing the film effectiveness not only for round but also the fan-shaped holes.
Starting from the base-type device, a robust optimization using Taguchi Method has been made by the present authors and will be reported as Part II.
Experimental Investigations of SYCEE Film Cooling Performance on a Plate and a Tested Vane of an F-Class Gas Turbine
Authors: Han Chang , Ren Jing , Jiang Hongde 
Published: September 2014

Film cooling is widely used in modern gas turbines for the protection of the hot components against hot gases from the combustion process. Film cooling directly influences the thermal efficiency of the gas turbine, as the cooling gas is extracted from the compressor and mixed with the mainstream in the hot component. Huge efforts by industry as well as research organizations have been undertaken to improve the film cooling effectiveness. It can been concluded that there are two key points for the improvement of film cooling effectiveness, constraining the blow-off of cooling ejection and extending the lateral coverage of cooling gas. The paper presents a new cooling technology, which reaches high film-cooling effectiveness as a result of a well-designed cooling hole, named SYCEE film cooling technology (SFCT). Plate film cooling experiments of SYCEE tested by pressure sensitive paint (PSP) are carried out in this work, and traditional shape-hole are included as well for baselines. It is resulted that SFCT has a better film cooling performance than shape-hole in the same conditions, and the gap of the averaged film cooling effectiveness between them continuously enlarges as the blowing ratio increases.
Furthermore, an application of SFCT on the first stage vane of an F-class gas turbine is studied as well. A two-dimension cascade has been employed to measure the cooling performance of SFCT using pressure sensitive paint (PSP) as well, and the tested vanes separately with round-hole and shape-hole are considered again for baselines. The different kinds of film holes separately locate on the pressure and suction side, while the showerhead in different cases are kept the same, arranged with round-holes. The cooling air is ejected at inclination angle 45° with compound-angle 90° in the showerhead and inclination angle 35°∼45° without compound-angle on the pressure side and suction side. The detailed local cooling effectiveness distributions as well as the span-averaged effectiveness over the vane surface are presented. As expected, the film cooling performance of round-hole is the worst due to the lift-off of the cooling ejection. SFCT has better film cooling performance than shape-hole on the pressure side, but the advantage decreases along the mainstream direction. However, the span-averaged film cooling effectiveness of SYCEE is similar with that of the shape-hole on the suction side. This may be due to enhanced impact of mainstream flow derived from the pressure gradient in the turbine passage, and consequently weakening the effect of film hole on the suction side.