bluuebunny/crossref_metadata_2025_split huggingface dataset:
Numerical and Experimental Analysis of Radial Clearance Influence on Rotor and Stator Clocking Effect by Example of Model High Loaded Two Stage Compressor
Authors: Mileshin V. I. , Savin N. M. , Kozhemyako P. G. , Druzhinin Ya. M. 
Published: September 2014

It is ascertained that optimization of bladed rows clocking positions is an effective tool for control of bladed rows unsteady interaction in a multistage turbo machine and could be used equally in refinement and in compressor design stages [1–3].
Up to now the clocking effect issue of highly loaded rotors in compressor stages was not investigated due to growing design complexity of the experimental facility. The issue concerning tip clearances value influence on rotor and stator clocking effects was not studied as well.
In the frames of this work a two stage compressor (HPC2 with the designed pressure ratio π* = 3.7 [4]) with a unique design was developed to investigate influence of tip clearance values on rotor and stator clocking effect. In order to realize the clocking effect the HPC2 compressor has the following parameters: numbers of stator blades are identical for all stators and equal to ZIGV = ZS1 = ZS2 = 68; number of R1 blades is two times less than of R2: ZR2 = 56, ZR1 = 28.
This work studies HPC2 compressor performances at 3 R1 and R2 tip clearances — dtip = 0.5mm – nominal clearance, 0.75mm, and 1.0 mm – increased clearance. Clocking effects of stators and rotors are tested at 0.5mm and 0.75mm tip clearances for two values of corrected rotational speeds — n = 0.7 and 0.88. As shown, variations in max. efficiency from maximum to minimum when changing the clocking position both the stator and the rotor reach Δη*ad≈0.008÷0.012 at dtip = 0.5mm or Δη*ad≈0.007÷0.008 at dtip = 0.75mm.
For more detailed analysis of the tip clearance influence on rotor and stator clocking effect a mathematical model of HPC2 was developed on base of through flow 3D viscous unsteady flow computations in the HPC2 compressor rows [3–4]. In full unsteady statement the calculation domain includes the following number of blade rows: IGV = 2, R1 = 1, S1 = 2, R2 = 2; S2 = 2.
Optimization of Film-Cooling Holes Shape by Principal Components Method and CFD
Authors: Vinogradov Kirill A. , Didenko Roman A. , Karelin Dmitry V. , Remizov Alexander E. 
Published: September 2014

The development of effective cooling systems is one of the most actual and difficult problems of development of gas-turbine engines. Significant amount of works is devoted to the research of characteristics and optimization of the film cooling holes shape. Different shapes of holes are investigated at various working conditions. However, the development of optimization methods of film cooling holes shape is covered insufficiently.
Optimization methods are widely applied for solving modern optimization problems on the basis of surrogate models. The most famous one is the method of response surface. The aim of this method is to construct an approximation response surface of the objective function. It is also necessary to create and evaluate many variants of the investigation object design and therefore to conduct the same amount of CFD calculations or experiments in order to provide the acceptable design of an experiment (DOE). Such number of points on the response surface results in extreme computational costs increasing, i.e. so called “Curse of Dimension”.
The main objective of the current paper is to develop the method to improve film-cooling holes shape along with minimum time and computational costs and acceptable accuracy of the surrogate model. Besides, the analysis of optimization results is considered.
In the structural-parametrical analysis, methods of transformation of multidimensional information are used to generalize geometrical parameters of film cooling holes shape. The optimization process is carried out by means of random search methods. As a result, the “fast” surrogate model featuring acceptable accuracy was obtained. Then by regression analysis methods the structural coupling equation (SCE) between the principal components of holes shape and its cooling effectiveness was obtained. The authors carried out the study of the optimum variant of a film cooling holes shape in the space of the principal components. Geometrical information of the optimized variant has been obtained and further calculation of its characteristics was carried out by means of the “reverse recovery” technology developed.
Finally, the offered method enables us to get the film-cooling holes geometry variant with a higher level of cooling effectiveness compared to the considered classical variants. Thus, the offered way of optimization provides eightfold decrease in necessary number of CFD calculations compared to the classical approach (DOE and the response-surface methods).
Analysis of the Noise Level Generated by Axial Flow Fan Composed of Radial-Bladed Centrifugal Rotor
Authors: Borges S. S. , Barbieri R. , Zdanski P. S. B. 
Published: September 2014

The objective of this work is to present, by means of experimental, analytical and numerical techniques that sound pressure level generated by radial-bladed centrifugal fans of electric motor cooling systems may be expressed by a logarithmical ratio of the peripheral velocity of rotor, volumetric flow and efficiency of the fan. The proposed methodology proved to be efficient and simple in the prediction of generated noise by radial-bladed centrifugal fans of TEFC motors with accuracy of ± 3 dB.
In addition, the acoustic resonance mode of the fan cavity were determined by means of numerical simulations, which its results were validated through experiments using waterfall spectrum.
Real-Time Burst Signal Removal Using Multi-Color Pyrometry Based Filter for Improved Jet Engine Control
Authors: Wang Guanghua , Estevadeordal Jordi , Harper Sean P. , Nirmalan Nirm 
Published: September 2014

Online line-of-sight (LOS) pyrometer is used on certain jet engines for diagnosis and control functions such as hot-blade detection, high-temperature limiting, and condition-based monitoring. Hot particulate bursts generated from jet engine combustor at certain running conditions lead to intermittent high-voltage signal outputs from the LOS pyrometer which is ultimately used by the onboard Digital Engine Controller (DEC).
To study the nature of hot particulates and enable LOS pyrometer functioning under burst conditions, a Multi-Color Pyrometry (MCP) system was developed under DARPA funded program and tested on an aircraft jet engine. Soot particles generated as by-product of combustion under certain conditions was identified as the root cause for the signal burst in a previous study. The apparent emissivity was then used to remove burst signals.
In current study, the physics based filter with MCP algorithm using apparent emissivity was further extended to real-time engine control by removing burst signals at real time (1MHz) and at engine DEC data rate. Simulink models are used to simulate the performances of the filter designs under engine normal and burst conditions. The results are compared with current LOS pyrometer results and show great advantage. The proposed model enables new LOS pyrometer design for improved engine control over wide range of operating conditions.
Experimental Investigations on Cooling Hole Diameters of an Impingement-Effusion Cooling System
Authors: Li Xiaopei , He Yuelong , Mao Ronghai , Fan Renyu , Xu Rongsun , Zhang Bo 
Published: September 2014

Cooling holes are playing critical roles in the impingement-effusion cooling system. The present experimental investigation have studied the effects of the hole diameters on the cooling efficiency and discharge coefficient. The main flow was heated up via combustion, with a maximum outlet temperature 850K. Cooling air, on the other hand, is supplied by an MAM-200 compressor. Temperature distribution on the hot side of the effusion plate is measured by a thermal infrared imaging camera calibrated by 5 thermocouples embedded in the tested plate. A filter is used to minimize the radiation from the hot gas.
Cooling holes, both the effusion holes and impingement holes are designed in staggered arrangement; and the number of effusion holes is almost equal to the impingement holes. The inclination angle of the effusion holes in the streamwise direction is 20 degree with respect to the liner surface. The pressure drop across the cooling system ranges from 3% to 5% of the total pressure of the inlet flow. Temperature distributions are measured with an infrared thermal imaging system. The length of the holes is kept to be constant. Three various effusion hole diameters/length ratio 0.3, 0.35, 0.43, with impingement hole diameters/length ratio 0.4, 0.47 and 0.6 correspondingly, have been tested and compared. The experimental results indicate that with the increasing of cooling hole diameters, discharge coefficient is also increased. Nevertheless, cooling efficiency reached its maximum with the effusion hole diameter/length ratio 0.35.
CFD Analysis of Suction and Pressure Side Film Cooling Influence on Vane Aero Performance in a Transonic Annular Cascade
Authors: Alameldin Ahmad , El-Gabry Lamyaa A. , Fridh Jens , Saha Ranjan 
Published: September 2014

Operating at temperatures well above their melting point, gas turbines’ components are subject to terribly high thermal stresses. In order to keep them intact and performing, different cooling techniques are implemented. One of these methods is film cooling.
Film cooling implementation in vane cascades has a potential loss expense. Proper assessment of its impact on the vane performance has to be conducted. The CFD approach of modeling each hole and cooling tube autonomously is very computationally expensive. In the current work an assessment of a new, more computationally efficient CFD approach for modelling film cooling was conducted on a vane cascade operating in the transonic regime (M = 0.89). The film cooling holes were represented by orifice boundary condition at the vane surface, omitting the need to model internal coolant plenum and cooling tubes mesh, resulting in 180% reduction in grid size and attributed computational cost interpreted in 300% saving in computation time.
Uncooled, and film cooled with different configurations and at different blowing ratios (BR) simulations were performed and compared to experimental measurements. A good agreement was obtained for the exit flow angles, vorticity and aerodynamic loss for all the cases (uncooled and cooled). Pitch-averaged exit flow angle outside endwalls regions remains unchanged for all cooling configurations and blowing ratios. The aerodynamic loss was found to be more sensitive to increasing the blowing ratio on the suction side than on the pressure side.
The proposed approach of coolant injection modeling is shown to yield reliable results, within the uncertainty of the measurements in most cases. Along with lower computational cost compared to conventional film cooling modeling approach, the new approach is recommended for further analysis for aero and thermal vane cascade flows.
The Impact of Realistic Inlet Swirl in a 1 ½ Stage Axial Turbine
Authors: Schmid Gregor , Krichbaum Alexander , Werschnik Holger , Schiffer Heinz-Peter 
Published: September 2014

Further improvements of gas turbine design can be expected if realistic turbine inlet conditions are applied. These include discrete swirl cores and hot spots which exit from the combustion chamber. A large scale turbine rig is currently reconfigured at Technische Universität Darmstadt to analyse the effect of realistic swirl intensity on turbine flow and heat transfer. A comparison is to be made between swirling and axial inflow conditions. The swirl generator causes a recirculation zone inside the combustion chamber. As a result, the total pressure at turbine inlet is reduced at midspan and increased near the end walls. In addition, incidence angles of ±15° occur at hub and casing of the nozzle guide vane (NGV). This swirl and the shape of the pressure profile are typical for modern lean combustion concepts which are relevant to reduce emissions like NOX.
During the design of the test rig, computational flow simulations are carried out. Different swirl orientations and clocking positions are investigated in advance. Depending on these parameters, there is a potential of 0.5 % efficiency between the optimal and the worst configuration. Comparing swirling with axial inflow conditions, an efficiency deficit of more than 2 % has been found which is mainly due to the increased turbulence level for swirling flow. In addition, heat transfer through the NGV hub is increased by approximately 20%. This paper aims for understanding the generation of these aerodynamic and thermal losses to allow for their elimination in future engine designs. Therefore, the most complex case of a realistic swirl generator is successively simplified towards a case with axial inflow: Two-dimensional inflow conditions including discrete swirl and loss cores are compared to radial distributions of inflow variables and globally constant values. The influence of swirling inflow, total pressure profile and turbulence level are simulated separately in order to identify their individual impact on aerodynamic and thermal losses.
Rotor Lifecycle Management Program
Authors: Wrobel Michal , Richter Mark , Zimmermann Rene , Kiewel Holger , Ullrich Andreas 
Published: September 2014

Minimizing the maintenance costs has become an ever growing topic in the power generation industry. Consequently, OEM’s constantly increase their efforts to exploit the full lifetime potential of capital intensive components, as for instance gas turbine rotors. More than ever, it is essential to have a closed loop from the design knowledge to solid facts about the actual condition of a gas turbine rotor in the field, in order to optimize the utilization and therefore to reduce total lifecycle costs.
During initial design an iterative component design process is applied, comprising of analytical calculations and component and engine tests, to design a reliable, robust and maintenance friendly component. Individual component risk profiles (i.e. failure probability and consequences) have to be taken into account during the design phase to cover uncertainties regarding the operating regime, operating conditions and environment, resulting in the minimum expected lifetime.
The lifetime of gas turbine components is limited and primarily depends on factors like the operating regime, dictating the mechanical and thermal loads, actual material properties, environmental conditions and the level of maintenance. Those parameters have a scatter and also interact with each other. As a consequence the progress of component degradation varies and the individual component lifetime isn’t known in detail at the time of the design.
The purpose of a Rotor Lifecycle Management Program is to detect individual component degradation early in the lifecycle, in order to exploit the maximum rotor lifetime while ensuring safe operation.
Periodic monitoring and condition assessment of the individual rotor is the first step, performed during standard type C inspections and comprising of visual inspection, dimensional and advanced non-destructive measurements. Typically the monitoring schedule is based on the operating regime and the operating history of the specific rotor.
The combination of the monitoring results with validated analytical design models, extensive material data and the overall gas turbine rotor fleet experience of the OEM, allows proper planning of lifetime extension measures, such as repair and reconditioning activities. Specific repair solutions for both on-site and shop applications have been developed.
A rotor lifecycle management program is a „living” program. The monitoring scope and schedule as well as the repair solutions portfolio are continuously optimized and adapted as a result of detailed analysis of operating data and inspection results of the whole global fleet.
CFD Analysis of the Aerodynamics and Aeroacoustics of the NASA SR2 Propeller
Authors: Tan Chun Hern , Voo Keng Soon , Siauw Wei Long , Alderton James , Boudjir Amel , Mendonça Fred 
Published: September 2014

NASA’s SR2 8-bladed propeller rotating at 6487rpm [1, 2, 3, 4] Advance Ratio of 3.06 and Mach Number of 0.6 is used to assess the aerodynamic and noise performance prediction capabilities of a standard commercial CFD code.
The main purpose of this study is to benchmark the performance prediction against experimental data for Power Coefficient and near-field noise measurements. Comparisons are made between single rotating and multiple rotating regions across a sliding mesh interface. We also focus on the effectiveness of capturing the downstream convection of tip vortex structures, in the wake of the propeller, modeled with all 8 blades, with a view towards using the approach to understand the interaction of these wake features with aerodynamic surfaces.
Noise predictions are performed using the standard FfowcsWilliams-Hawkings impermeable surface method for rotating dipoles. This is compared with near-field noise predictions using direct noise simulation from the unsteady compressible CFD code and experimental data, in terms of the measured dB intensity at the blade passing frequency and harmonics.
Additional unsteady CFD simulation was conducted for a separate SR2 propeller with a calibrated blade angle. The preliminary results of the direct near-field noise computation of dB intensity at the blade passing frequency have shown improved agreement with wind tunnel data at aft angles to the propeller plane.
Practices are demonstrated which result in low dependency on the sliding mesh interface location. Tip vortex structures and downstream convection are well captured by judicious choice of mesh refinement in the wake of the propeller.
Comparison of Gas Turbines and Power-to-Gas Plants for Improved Wind Park Energy Dispatchability
Authors: Guandalini Giulio , Campanari Stefano , Romano Matteo C. 
Published: September 2014

According to IEA projections for the year 2050, up to 50% of the energy demand in the next decades could be covered by non-programmable sources (e.g. wind and solar power), which can significantly affect power quality, grid stability and power generation planning. Moreover, in several countries a fast growth of installed power based on renewables could not be followed by a simultaneous growth of local grid capacities, leading to increase probability of load shedding events, reducing the productivity of renewable power plants.
In this perspective, an important role will be played by technologies which allow improving the dispatchability of non-programmable renewable power plants like wind parks.
While a classical approach to grid power modulation relies on gas turbines, an increasing attention is given nowadays to new technologies, not based on fossil fuels, specially focusing on the adoption of energy storage systems. Among these options, one of the most promising relies on the “power-to-gas” concept, which consists in producing hydrogen by water electrolysis and injecting it into the natural gas infrastructure, as currently considered by some research projects and demonstration-scale plants.
With respect to hydrogen storage technologies, this option limits the need of a local hydrogen storage reservoir, reducing the investment costs, improving the renewable fraction of gaseous fuels and allowing to oversize the renewable installed power with respect to the grid capacity.
In this work a preliminary investigation of the economic feasibility of this system is carried out, starting from the example of the forecasted scenario of wind power evolution in some EU countries. A statistical approach is applied in order to evaluate the error in energy production forecasts. As results, a preliminary sizing of the whole system is proposed, estimating the economic outlook, the possible annual energy and emission balances and the influence of the uncertainty in declared production from wind power plants.
A comparison with power modulation based on gas turbines is set up in order to evaluate which are the parameters that influence the economic viability of both solutions, evidencing the different operational criteria of the two systems and their impact on the dispatchability of energy.
Impact of Low-Rank Coal on Air-Blown IGCC Performance
Authors: Giuffrida Antonio 
Published: September 2014

This paper presents simulation results of air-blown coal gasification-based combined cycles when using low-rank coals, by means of a previously realized thermodynamic model. In detail, besides considering a sub-bituminous coal, attention is also paid to a brown coal, pre-dried to reduce its high moisture content.
When gasifying a sub-bituminous as received coal the results highlight a slight reduction in IGCC LHV efficiency, with an absolute difference less than 1 percentage point if compared to the case with bituminous coal. This result is accomplished with an increase in net power output (almost 8 percentage points).
As concerns the brown coal, a pre-drying before gasification is considered because of its significant moisture content (65 wt%). In particular, three cases with different pre-drying levels are analyzed, with the highest residual moisture content limited to 30 wt%. Even considering an energy-saving technology as the fluidized bed dryer with integrated waste heat recovery, the specific demand for coal drying amounts to 2.1–2.3 percentage points referred to the (pre-dried) coal thermal input, seriously affecting both the final IGCC efficiency and its power output in comparison with the case of bituminous coal. Higher residual moisture in coal leads to lower IGCC efficiency, whereas the net power is always less than the one delivered by the plant with the sub-bituminous coal. However, comparing the cases with sub-bituminous coal and brown coal with the minimum moisture content (10 wt%), LHV and HHV efficiencies present opposite trends, since HHV efficiency for the case with brown coal is even better than with sub-bituminous coal.
Feasibility Assessment for ORC Generation System Development Using Low Temperature Geothermal Water
Authors: Kho Seonghee , Ki Jayoung , Kang Myoungcheol 
Published: September 2014

Since around 70°C of geothermal water exists in Seokmo-do of Republic of Korea, this study is to assess the feasibility of electricity generation by utilizing ORC system, and the pertinent economic impact.
It is generally believed that economic feasibility can be secured only when the source of geothermal water is above 100°C in order to generate electricity by operating ORC system.
However, there was an exceptional case that ORC system was commercialized by Pratt-Whitney for around 70 °C of geothermal water in the hot springs of Chena, Alaska.
The annual average temperature in the hot springs of Chena, Alaska is approximately 1°C whereas that of Seokmo-do is around 11°C, which makes 10°C of annual average temperature difference in operational environment between the two. Thus, the 2 phases of absorption refrigerating machine is considered for the ORC generation system.
With establishing ORC system in consideration of operational environment, the feasibility of the development of ORC system in Seokmo-do is assessed by performance analysis and economic feasibility.
As a result of the assessment, it is identified that the economic feasibility can be secured if the price of electricity is over $0.42/kWh same as that of photovoltaic generation as an incentive of the RPS program granted by the Korean government.