bluuebunny/crossref_metadata_2025_split huggingface dataset:
Application of the Transient Test Technique to Measure Local Heat Transfer Coefficients Associated With Augmented Airfoil Cooling Passages
Authors: Saabas H. J. , Arora S. C. , Messeh W. Abdel 
Published: March 2015

The failure of a turbine airfoil is a local phenomena. However, to date, the design of these airfoils has been based on steady state heat transfer tests that are capable of yielding only locally averaged data. To overcome this limitation, a transient technique using active surface coatings has been developed and is capable of yielding local data. This technique has been used to determine the Nusselt number distributions within augmented passages typical of gas turbine airfoils. However, certain assumptions have been made in these analyses without verification. This paper will address this aspect of the problem, as well as an improved data reduction procedure, and an alternative error analysis.
The data reduction procedure has been improved by incorporating a higher order approximation to the convective boundary condition, and by introducing a means of calculating the fluid bulk temperature-time-space profile. An image analysis system which yields an unbiased means of determining the time required for the surface to reach a specified temperature is introduced. Furthermore, it was observed that for augmented surfaces, the one dimensional conduction assumption made in the heat transfer solution is not valid for all times. Finally, treating the experimentally obtained quantities as values that are randomly distributed about some true value is not correct for all experimentally measured quantities.
A Method for Calculating Turbulent Boundary Layers and Losses in the Flow Channels of Turbomachines
Authors: Schumann Lawrence F. 
Published: March 2015

An interactive inviscid core flow-boundary layer method is presented for the calculation of turbomachine channel flows. For this method, a one-dimensional inviscid core flow is assumed. The end-wall and blade surface boundary layers are calculated using an integral entrainment method. The boundary layers are assumed to be collateral and thus are two-dimensional. The boundary layer equations are written in a stream-line coordinate system. The streamwise velocity profiles are approximated by power law profiles. Compressibility is accounted for in the streamwise direction but not in the normal direction.
Equations are derived for the special cases of conical and two-dimensional rectangular diffusers. For these cases, the assumptions of a one-dimensional core flow and collateral boundary layers are valid. Results using the method are compared with experiment and good quantitative agreement is obtained.
AGT101: Ceramic Gas Turbine Development
Authors: Boyd G. L. , Easley M. L. , Kreiner D. M. 
Published: March 2015

A major technical effort has resulted in recent testing of the all-ceramic hot section in the DOE/NASA sponsored AGT101 Advanced Gas Turbine. This testing was preceded by critical component developments including ceramic structures design evolution to satisfactorily pass the peak stress start transients with 25-percent margin. Ceramic structures test evaluation at 2500F (1371C), ceramic combustor operation on various fuels and ceramic static seal leakage reduction have been necessary for the ceramic engine test. The most challenging ceramic component, the turbine rotor, has undergone successful fabrication development, but further process and material development are necessary to meet the high temperature durability goals.
The 100-hour engine test of the ceramic structures to 2100F (1149C), and the later 85-hour engine test of the all-ceramic hot section to 2200F (1204C) have been important program accomplishments. Full speed operation to 100,000 rpm and a ceramic rotor tip speed of 2300 ft/sec (701 m/s) has been demonstrated. The ability of these experimental gas turbines to operate in a regime where the unique properties of structural ceramics can be exploited offers the opportunity to further advance ceramic technology.
Pressure Distributions in the Tip Clearance Region of an Unshrouded Axial Turbine as Affecting the Problem of Tip Burnout
Authors: Bindon Jeffery P. 
Published: March 2015

The pressure distribution in the tip clearance region of a 2D turbine cascade was examined with reference to unknown factors which cause high heat transfer rates and burnout along the edge of the pressure surface of unshrouded cooled axial turbines.
Using a special micro-tapping technique, the pressure along a very narrow strip of the blade edge was found to be 2.8 times lower than the cascade outlet pressure. This low pressure, coupled with a thin boundary layer due to the intense acceleration at gap entry, are believed to cause blade burnout. The flow phenomena causing the low pressure are of very small scale and do not appear to have been previously reported.
The ultra low pressure is primarily caused by the sharp flow curvature demanded of the leakage flow at gap entry. The curvature is made more severe by the apparent attachement of the flow around the corner instead of immediately separating to increase the radius demanded of the flow. The low pressures are intensified by a depression in the suction corner and by the formation of a separation bubble in the clearance gap. The bubble creates a venturi action. The suction corner depression is due to the mainstream flow moving round the leakage and secondary vortices.
Design Criteria and Efficiency Prediction for Radial Inflow Turbines
Authors: Perdichizzi Antonio , Lozza Giovanni 
Published: March 2015

A theoretical investigation was performed to predict the maximum achievable efficiency of radial inflow turbines for different design conditions. The analytical tool used in the investigation is a computer code able to perform the contemporary optimization of the main design variables, in order to obtain maximum efficiency. Since the results are strictly dependent on the loss correlations, reliability of the efficiency predictions was tested at first by comparison with several test-cases available in literature: good agreement with experimental data was found, pointing to the validity of the results presented here.
A large number of cases were analyzed: the efficiency and the main design parameters, obtained after the optimization process, are presented for optimum specific speed. Turbine efficiency was found to be dependent both on compressibility effects, related to the volume expansion ratio, and on actual turbine size, accounting for geometric non-similarity effects. Influence of non-optimum specific speed is also discussed.
By means of similarity rules, the results enable turbine design to be performed in a simple way, for a variety of working fluids and design conditions.
Theoretical and Experimental Analysis of a Compressor Cascade at Supercritical Flow Conditions
Authors: Weber A. , Faden M. , Starken H. , Jawtusch V. 
Published: March 2015

A comparison theory - experiment in terms of profile Mach number distribution, loss behavior and exit flow angle has been made for a compressor rotor cascade at M1 = 0.85. Measurements in the cascade wind tunnel and calculations were performed over the whole incidence range.
(A) A 2-D finite element method applied to the full potential equation is used as analysis code.
(B) Viscous effects are considered by using McNally’s integral boundary layer method with additional procedures for laminar and turbulent separation and shock boundary layer interaction.
(A) and (B) are coupled iteratively by adding the displacement thickness to the metal blade contour.
(C) The averaged exit flow properties and the total pressure loss coefficient are evaluated by application of the conservation laws.
Design and Application of a Natural Gas Pipeline Optimization Program
Authors: Gilmour Jill 
Published: March 2015

A software package which optimizes natural gas pipeline operation for minimum fuel consumption is in use on a commercial transmission pipeline. This Optimization Program has resulted in pipeline fuel savings in daily pipeline operation. In addition, the effect of a new compressor/turbine unit on the pipeline system as a whole can be accurately and easily quantified through use of the Optimization Program before the unit is even installed. The results from one turbine replacement study showed the total system fuel consumption and operating hours predicted for each unit were not directly related to a high turbine efficiency.
This paper describes the simulation techniques used for the gas turbine and compressor modeling. The methodology behind the system-wide optimization is also provided, along with a detailed discussion of the program application to gas turbine and compressor replacement studies.
Research and Development on the HPT of the AGTJ-100B
Authors: Arai Masashi , Imai Tetsu , Teshima Kiyomi , Koga Akinori 
Published: March 2015

The final target of development of the advanced gas turbine sponsored by MITI of Japan is a thermal efficiency of over 55% at an HPT inlet temperature of 1400°C as a combined plant. In order to attain this target, a feasibility study of the design and various R & D tasks have been conducted.
This paper will first present the basic plan and then some important R & D items.
Development of a High Pressure Dry Coal Feed System for a Two-Stage Slagging Gas Turbine Combustor
Authors: LeCren R. T. , White D. J. 
Published: March 2015

Solar Turbines Incorporated, under the sponsorship of DOE-Morgantown Energy Technology Center has developed an advanced gas turbine coal-fired two-stage slagging combustor (TSSC). Rig test results using various coal-water mixtures have been reported previously (ASME 85-GT-206 and 85-JPGC/GT-17).
As part of the program it was required that the performance of the TSSC when operated with dry micronized coal be compared to that when burning coal water mixtures. As a prerequisite to this performance testing, a reliable high-pressure dry coal feed system had to be developed. A dense-phase feed and transport system was selected as the best compromise that satisfied the various needs. The system design development included the design and testing of a splitter system that divided the primary feed into four secondary flows. A number of problems were encountered and corrected during the testing. These problems, their solutions and the final system configurations are described. A comparison of the emissions using CWM and dry micronized coal is also presented. In general, NOx is higher and CO and UHC are lower on dry coal than on CWM because of the reduction of the reaction zone temperature by the water.
Feasibility Test of a Low Emissions Topping Combustor for Fluidized Bed Applications
Authors: Pillsbury Paul W. , Garland Richard V. 
Published: March 2015

Combined cycles utilizing fluidized bed combustors, whether they be atmospheric or pressurized, are temperature limited. In order to capture sulfur effectively, bed operating temperature and, therefore, the gas turbine inlet temperature is limited to about 1600°F (1144 K) (Makanski and Schweiger, 1982) in atmospheric beds, and about 1700°F (1200 K) in pressurized beds as reported in DOE/METC/SP-185 (1980). In some applications, material limitations also come into play. While these systems show encouraging economics, they can be enhanced substantially by increasing the turbine inlet temperature. An atmospheric fluidized bed (AFB) example is discussed in this paper.
The addition of a topping combustor, thereby increasing the turbine inlet temperature in fluidized bed combined cycles, provides the means for increasing power output which enhances plant economics. Although emissions control and maintaining acceptable wall temperatures are achieved through the application of the multi-annular swirl burner, the design of such a combustor requires careful consideration of cooling and combustion because of the inherently higher cooling air and combustion air temperatures.
Experimental Study on the Atomization of Plain Orifice Injector Under Uniform and Non-Uniform Cross Flowing Air Stream
Authors: Zhang Yan , Zhu Jun Yong , Wang Li Xin , Chin Ju Shan 
Published: March 2015

The effects of three parameters: air velocity, nozzle pressure drop and injector orifice diameter, on the spray characteristics of a plain orifice injector under uniform and non-uniform cross flowing air stream have been studied experimentally. For uniform cross flowing air stream, the results show that the effects of these parameters are interrelated. The exponents of these terms in a correlation are not constants. Based on a very large amount of experimental data, the following correlation has been derived for Sauter Mean Diameter.
SMD = 8.28 • 10 4 V ¯ a A • Δ P ¯ f B • d ¯ C
where:
A = −1.59 −0.0044ΔP̄f −0.01 d̄
B = −0.13 −0.025 d̄ +0.34 Ma
C = 0.36 −0.55 Ma −0.0032ΔP̄f
(Va ≤ 140 M/s ; ΔPf ≤ 11 Kg·f/cm2 ; d ≤ 2.5 mm)
For small orifice diameters, the drop size distribution parameter, N (Rosin-Rammler distribution ), decreases until a minimum then increases with air velocity. For large orifice diameters, it decreases with air velocity. N always decreases with the increases of nozzle pressure drop or orifice diameter.
For non-uniform cross flowing air stream, atomizations under four velocity profiles with same averaged velocity and with a velocity recess of same shape but at different radial positions have been tested. The atomization data were compared with that of uniform cross flowing air stream. Two types of comparison were made based on: a) the undisturbed velocity, b) the averaged velocity, equals to the velocity of uniform cross flowing air stream. For former situation the atomization for non-uniform cross flowing air stream tested is always poorer. The influence from the velocity recess will be maximum at certain nozzle pressure drop.
The experimental evidence obtained has shown that cross flow atomization is a combination of pressure atomization (at low air flow velocity) and airblast atomization (at high air flow velocity).
Development and evaluation of a method of calibrating medical displays based on fixed adaptation
Authors: Sund Patrik , Månsson Lars Gunnar , Båth Magnus 
Published: March 2015

Purpose:The purpose of this work was to develop and evaluate a new method for calibration of medical displays that includes the effect of fixed adaptation and by using equipment and luminance levels typical for a modern radiology department.Methods:Low contrast sinusoidal test patterns were derived at nine luminance levels from 2 to 600 cd/m2 and used in a two alternative forced choice observer study, where the adaptation level was fixed at the logarithmic average of 35 cd/m2. The contrast sensitivity at each luminance level was derived by establishing a linear relationship between the ten pattern contrast levels used at every luminance level and a detectability index (d′) calculated from the fraction of correct responses. A Gaussian function was fitted to the data and normalized to the adaptation level. The corresponding equation was used in a display calibration method that included the grayscale standard display function (GSDF) but compensated for fixed adaptation. In the evaluation study, the contrast of circular objects with a fixed pixel contrast was displayed using both calibration methods and was rated on a five‐grade scale. Results were calculated using a visual grading characteristics method. Error estimations in both observer studies were derived using a bootstrap method.Results:The contrast sensitivities for the darkest and brightest patterns compared to the contrast sensitivity at the adaptation luminance were 37% and 56%, respectively. The obtained Gaussian fit corresponded well with similar studies. The evaluation study showed a higher degree of equally distributed contrast throughout the luminance range with the calibration method compensated for fixed adaptation than for the GSDF. The two lowest scores for the GSDF were obtained for the darkest and brightest patterns. These scores were significantly lower than the lowest score obtained for the compensated GSDF. For the GSDF, the scores for all luminance levels were statistically separated from the average value; three were lower and two were higher. For the compensated GSDF, three of the scores could not be separated from the average value.Conclusions:An observer study using clinically relevant displays and luminance settings has demonstrated that the calibration of displays according to the GSDF causes the perceived contrast to be unevenly distributed when using displays with a high luminance range. As the luminance range increases, the perceived contrast in the dark and bright regions will be significantly lower than the perceived contrast in the middle of the luminance range. A new calibration method that includes the effect of fixed adaptation was developed and evaluated in an observer study and was found to distribute the contrast of the display more evenly throughout the grayscale than the GSDF.
Predicting adenocarcinoma recurrence using computational texture models of nodule components in lung CT
Authors: Depeursinge Adrien , Yanagawa Masahiro , Leung Ann N. , Rubin Daniel L. 
Published: March 2015

Purpose:To investigate the importance of presurgical computed tomography (CT) intensity and texture information from ground‐glass opacities (GGO) and solid nodule components for the prediction of adenocarcinoma recurrence.Methods:For this study, 101 patients with surgically resected stage I adenocarcinoma were selected. During the follow‐up period, 17 patients had disease recurrence with six associated cancer‐related deaths. GGO and solid tumor components were delineated on presurgical CT scans by a radiologist. Computational texture models of GGO and solid regions were built using linear combinations of steerable Riesz wavelets learned with linear support vector machines (SVMs). Unlike other traditional texture attributes, the proposed texture models are designed to encode local image scales and directions that are specific to GGO and solid tissue. The responses of the locally steered models were used as texture attributes and compared to the responses of unaligned Riesz wavelets. The texture attributes were combined with CT intensities to predict tumor recurrence and patient hazard according to disease‐free survival (DFS) time. Two families of predictive models were compared: LASSO and SVMs, and their survival counterparts: Cox‐LASSO and survival SVMs.Results:The best‐performing predictive model of patient hazard was associated with a concordance index (C‐index) of 0.81 ± 0.02 and was based on the combination of the steered models and CT intensities with survival SVMs. The same feature group and the LASSO model yielded the highest area under the receiver operating characteristic curve (AUC) of 0.8 ± 0.01 for predicting tumor recurrence, although no statistically significant difference was found when compared to using intensity features solely. For all models, the performance was found to be significantly higher when image attributes were based on the solid components solely versus using the entire tumors (p < 3.08 × 10−5).Conclusions:This study constitutes a novel perspective on how to interpret imaging information from CT examinations by suggesting that most of the information related to adenocarcinoma aggressiveness is related to the intensity and morphological properties of solid components of the tumor. The prediction of adenocarcinoma relapse was found to have low specificity but very high sensitivity. Our results could be useful in clinical practice to identify patients for which no recurrence is expected with a very high confidence using a presurgical CT scan only. It also provided an accurate estimation of the risk of recurrence after a given duration t from surgical resection (i.e., C‐index = 0.81 ± 0.02).
Psychosocial Aspects of Exercise and Physical Activity in Childhood
Authors: Kipp Lindsay E. 
Published: March 2015

Purpose:A signature characteristic of positive youth development (PYD) programs is the opportunity to develop life skills, such as social, behavioral, and moral competencies, that can be generalized to domains beyond the immediate activity. Although context-specific instruments are available to assess developmental outcomes, a measure of life skills transfer would enable evaluation of PYD programs in successfully teaching skills that youth report using in other domains. The purpose of our studies was to develop and validate a measure of perceived life skills transfer, based on data collected with The First Tee, a physical activity-based PYD program.Method:In 3 studies, we conducted a series of steps to provide content and construct validity and internal consistency reliability for the life skills transfer survey (LSTS), a measure of perceived life skills transfer.Results:Study 1 provided content validity for the LSTS that included 8 life skills and 50 items. Study 2 revealed construct validity (structural validity) through a confirmatory factor analysis and convergent validity by correlating scores on the LSTS with scores on an assessment tool that measures a related construct. Study 3 offered additional construct validity by reassessing youth 1 year later and showing that scores during both time periods were invariant in factor pattern, loadings, and variances and covariances. Studies 2 and 3 demonstrated internal consistency reliability of the LSTS.Conclusion:Results from 3 studies provide evidence of content and construct validity and internal consistency reliability for the LSTS, which can be used in evaluation research with youth development programs.