bluuebunny/crossref_metadata_2025_split huggingface dataset:
Study of Film Cooling Effectiveness on a Double-Walled Effusion-Cooled Turbine Blade in a High-Speed Flow Using Pressure Sensitive Paint
Authors: Ngetich Gladys C. , Ireland Peter T. , Romero Eduardo 
Published: November 2019

Abstract
A detailed analysis of film cooling performance on a double-walled effusion-cooled blade is essential for both the coolant consumption optimization and assessment of the film to offer the desired levels of the turbine blade protection. Yet there are hardly any film effectiveness studies on double-wall full-coverage film cooled turbine blades.
This paper presents a detailed film cooling effectiveness study over the full surface of a double-walled effusion-cooled high-pressure turbine rotor blade using Pressure Sensitive Paint (PSP). PSP permitted a non-intrusive and conduction-errors-free means of obtaining clean and distinct local distribution of film effectiveness on the blade surface making it possible to extract valuable film cooling effectiveness performance data on the whole blade surface.
Three large-scale circular pedestal double-wall blade designs with varying pedestal height, pedestal diameter and cooling hole diameter were tested in a high-speed stationary single-blade linear cascade running at engine-representative Mach and Reynolds numbers. All the blades were tested within a range of representative modern engine coolant mass flow, ṁc to mainstream, ṁg ratios; 1.6% < ṁc/ṁ∞ < 5.5%.
High porosity blade exhibited a better flow distribution and was found to consistently perform the best.
Vortical Structures in Pin Fin Arrays for Turbine Cooling Applications
Authors: Otto Marcel , Hodges Justin , Gupta Gaurav , Kapat Jayanta S. 
Published: November 2019

Abstract
Pin fin arrays are common features in the trailing edge region of turbine blades, and provide both structural integrity and increases in heat removal rates. Aforementioned pins act as fins by increasing the flow-wetted area, while also introducing complex flow structures such as von Kármán vortex shedding and horseshoe vortex systems; both directly affecting the global and local heat transfer characteristics over the endwall. The present study utilizes a wind tunnel to investigate the row to row interactions throughout a pin fin array comprised of four staggered rows, with spanwise and streamwise pitches of 2.5 pin diameters with a focus on the flow field downstream of the first row. The channel height to pin diameter ratio of 2. The Reynolds numbers tested based on pin diameter and local maximum velocity are 10,000 and 30,000. PIV is used as the experimental method of choice for acquiring quantitative flow data to study the flow field and derive high fidelity turbulence data and vortex structures with respect to the effects of the upstream rows on the pin fins downstream; this describes the underlying flow physics that drive the local Nusselt Number distribution on the cooled surface. Also, it was found that the wake structure varies over the two Reynolds Numbers significantly due to increased flow instabilities which promote shear layer separation and vortex formation. Flow acceleration due to neighboring pins confines the vortex formation in spanwise direction. The distribution of turbulent kinetic energy and the contribution of all Reynolds Stress Tensor components is reported. The turbulent scheme in the wake region is particularly anisotropic. The test section pressure drop is in agreement with literature for 30,000 Reynolds Number, but larger for smaller Reynolds Numbers. A thorough RANS simulation of the baseline case was conducted by carefully adjusting the turbulence model parameters to accurately reflect this particular experimental setup. The numerical results are in good agreement with heat transfer results and thus are utilized to further understand the underlying flow physics. However, the shear layer breakdown is underpredicted in numerical results resulting in shielded regions in the wake of the pin with artificially low heat transfer. The findings of the study contribute to better understanding of the underlying flow physics in a pin fin cooled airfoil and assist design engineers in making better internal cooling geometries.
Novel Method to Predict Non-Measured Parameters of Industrial Gas Turbines Using Kalman Filter Technique
Authors: Lee Jae Hong , Kim Tong Seop , Kang Do Won , Sohn Jeong Lak , Lee Jung Ho 
Published: November 2019

Abstract
Gas turbines are most widely used for power generation and operate under various conditions and loads. Gas turbine control is important to cope with various situations, and the turbine inlet temperature (TIT) is the most important parameter because it is directly related to the power output and life cycle of the turbine. Thus, precise prediction and control of the TIT are important in terms of the stable operation and life cycle management of gas turbines. This paper proposes a new method to predict non-measured parameters such as the air flow and TIT using Kalman filter techniques. The Kalman filter is widely used for estimating the instantaneous state of a system and can estimate non-measured parameters. The Kalman filter algorithm was implemented in a gas turbine analysis program using MATLAB. The reliability of the new method was verified through various case studies using virtual data and real operating data. The results were compared with those of a model-based gas turbine diagnostics program. The computing time of the Kalman filter and model-based diagnostics program were also compared to confirm the capability of the new method. The results indicate that the new method is more suitable for diagnostics and monitoring applications than the model-based analysis program. Finally, two case studies were performed to confirm the feasibility of the new method using two virtual datasets. The results confirm that the Kalman filter can predict the non-measured parameters precisely.
Experimental and Numerical Investigations on Flow Losses of a U-Bend and Return Channel System for Centrifugal Compressor
Authors: Xi Guang , Tian Yubao , Guo Yunpeng , Tang Yonghong , Wang Zhiheng 
Published: November 2019

Abstract
The flow losses in a U-bend and return channel system of an inter stage has an important influence on the stage performance. To study the flow characteristics in such system, a pseudo-stage which consists of pseudo guide vanes, U-bend and return channel, combined with a normal stage, was designed and its performance curves were measured at different machine Mach numbers. Simultaneously, the numerical simulations, in which different data processing methods of CFD post process were adopted, were performed and the prediction accuracy was verified by comparison with the experimental results. The results indicated that the design of pseudo guide vanes provides an approximately constant flow direction at the inlet of U-bend with the variation of inlet Reynolds number, which matches the blade metal angle of the return channel well. The further analyses on the measured and numerical results showed that the loss characteristics vary with the inlet Reynolds number. When the Reynolds number is greater than a critical Reynolds number, the loss coefficient in the U-bend and return channel keeps nearly constant. The non-uniformity of flow angle and total pressure at the outlet of return channel were also illustrated and discussed.
Effects of High Heating Loads on Unsteady Flow and Heat Transfer in a Cooling Passage With a Staggered Array of Pin Fins
Authors: Lee Chien-Shing , Shih Tom I.-P. , Bryden Kenneth M. , Dennis Richard A. 
Published: November 2019

Abstract
Time-accurate 3-D CFD simulations based on the SST-SAS turbulence model were performed to study the effects of heat load on the unsteady flow and heat transfer in a cooling duct with a staggered array of short pin fins. For this duct, the static pressure at its exit is maintained at 25 bars, and the cooling air that enters has a temperature of 673 K with a flow rate that produces a Reynolds number of 25,000. To examine the effects of heat load, the following isothermal wall temperatures were studied: 678 K, 873 K, 1073 K, and 1,273 K, which give rises to heat loads that range from 15 kW/m2 to 1.5 MW/m2. Results obtained show high heat loads to cause considerable changes in the temperature of the cooling flow along the duct, which causes significant changes in density and velocity as well as viscosity and thermal conductivity. These changes along the duct were found to affect the locations where unsteady flow separation take place around the pin fins, the magnitude of the vorticity shed in the wakes, and the shedding Strouhal number. These unsteady flow mechanisms in turn strongly affect the nature of the surface heat transfer. A correlation formula for the heat transfer, which accounts for the effects of heat loads, was developed.
Dynamic Behavior of the Ultra-High Efficiency Gas Turbine Engine, UHEGT, With Stator Internal Combustion
Authors: Ghoreyshi Seyed M. , Schobeiri Meinhard T. 
Published: November 2019

Abstract
The paper investigates the dynamic behavior of an Ultra-High Efficiency Gas Turbine Engine (UHEGT) with Stator Internal Combustion. The UHEGT-technology was introduced for the first time to the gas turbine design community at the Turbo Expo 2015. In developing the UHEGT-technology, the combustion process is no longer contained in isolation between the compressor and turbine, rather distributed in the first three HP-turbine stator rows. Noticeable improvement in the engine thermal efficiency and power along with other performance advantages are brought by this technology. In the current paper, a dynamic simulation is performed on the entire gas turbine engine (UHEGT) using the nonlinear dynamic simulation code GETRAN. The simulations are in 2D (space-time) and include the majority of the engine components including rotor shaft, turbine and compressor, fuel injectors, diffuser, pipes, valves, controllers, etc. The thermo-fluid conservation laws are applied to the flow in each component which create a system of nonlinear partial differential equations that is solved numerically. Two different fuel schedules (steep rise and Gaussian) are applied to all injectors and the engine response is studied in each case. The results show that fluctuations in the fuel flow lead to fluctuations in most of the system parameters such as temperatures, power, shaft speed, etc. However, the shapes and amplitudes of the fluctuations are different and there is a time lag in the response profiles relative to the fuel schedules. It is shown that an increase in average fuel flow in the system leads to a small drop in efficiency due to the cycle change from the design point. Moreover, it is seen that the temperatures usually rise fast with increase of fuel flow, but the system tends to cool down with a slower rate as the fuel is reduced.
Superposition Characteristics of Full Coverage Film Cooling With Various Blowing Ratio and Row Number
Authors: Wang Lang , Li Xueying , Li Weihong , Ren Jing , Jiang Hongde 
Published: November 2019

Abstract
Effusion cooling is the next step in gas turbine blade cooling to get the higher turbine inlet temperature, but the interaction between the front jet flow and the rear jet flow still need to be studied. In this paper, the effect of row number and blowing ratio are studied experimentally by PSP and numerically by RANS. One to five rows of staggered cooling holes were investigated with blowing ratio 0.5, 1.0 and 1.5. It is found that the income boundary layer helps the rear rows penetrate deeper to the main flow at low blowing ratio M = 0.5, the cooling performance become worse for single row. The performance at high blowing ratio M = 1.5 for row 3–5 is nearly not effected by income boundary layer due to blowing off. Finally, a corrected equation based on Sellers superposition method for full coverage film cooling is realized, which could explain the “fully developed level” and improve the accuracy of prediction of full coverage film cooling.
Kinetics Study of a Staged Combustor Concept for Oxy-Fuel Combustion Gas Turbine Cycles
Authors: Qian Wenkai , Liu Haoyang , Zhu Min , Li Suhui 
Published: November 2019

Abstract
Oxy-fuel combustion has been identified as a promising technology for CO2 capture and NOx reduction. It has great potential to be applied in gas turbine cycles. Previous studies, however, reveal that simple oxy-fuel combustors suffer from issues like flame blowoff and CO emissions especially at part load, due to the high CO2 content in the combustion atmosphere. In this paper, a staged combustor concept is proposed to mitigate flame blowoff and CO emissions issues for load operations. The conceptual combustor consists of three zones axially: primary zone, CO burnout zone, and dilution zone. All fuel is fed to the primary zone, while O2 is distributed to the primary zone and CO burnout zone. CO2 is distributed to the primary zone and dilution zone. By adjusting the distribution of the O2 and CO2, the primary zone operates at a relatively higher flame temperature at part load, which helps improve the flame blowoff performance. A chemical reactor network model is developed to study the effects of key design/operating parameters on flame blowoff and CO emissions. Results show that the distribution ratios of O2, CO2 and residence time between different zones are the key factors that influence flame blowoff and CO emissions. To mitigate flame blowoff and CO emissions at part load, the distribution of O2 needs to be carefully chosen so that the primary zone operates under near-stoichiometric or slightly lean condition, while the distribution of CO2 to the primary zone also needs to be reduced. The residence time split has stronger influence on CO emissions than CO2 and O2 distribution.
Suppression of Combustion Instabilities in a Premixed Swirl Combustor With Acoustic Liner
Authors: Xu Liangliang , Wang Guoqing , Mo Changcai , Liu Xunchen , Li Lei , Qi Fei , Sun Xiaofeng 
Published: November 2019

Abstract
Acoustic liner is one of effective passive control methods of combustion instabilities. This paper presents an experimental investigation about the suppression of the combustion instabilities using acoustic liners. A premixed swirling combustor was built and a specially designed acoustic liner was set at the downstream of the flame zone. Then, experiments of rigid wall, acoustic liner without and with tunable bias flow were carried out respectively. Furthermore, considering the viscous dissipation of airflow is temperature related, the temperature of the bias flow was adjusted in order to evaluate its effects on thermoacoustic instabilities. The bias flow was heated by electric taps before entering the acoustic liner in this rig. Results shows that the unstable Helmholtz mode could be triggered, and the oscillation amplitude grows with the increase of the bias flow Mach number, while the instability of 1/4 wavelength mode may be completely suppressed. Within the scope of the experiments, the unstable Helmholtz mode triggered by the bias flow can be attenuated by raising the bias flow temperature, while no substantial changes are observed about the quarter wave mode. These results are rarely reported in previous studies. Studying the effects of acoustic liner on combustion instabilities can provide useful knowledge regarding its application in real combustion systems.
Performance Analysis of a Hybrid Solar Gas Turbine Plant Combined With Chemical Recuperation
Authors: Wang Zhitao , Qi Wanling , Li Tielei , Li Shuying 
Published: November 2019

Abstract
This paper studies the influence of the high-temperature solar preheating system and chemical recuperation system on the overall performance of a MW-level three-shaft gas turbine. In order to obtain accurate simulation results, this paper adopts an integrated simulation method, where the simulation models of the solar receiver and gas turbine are established on the Matlab/Simulink platform, the simulation model of the chemical recuperation system is established on the Aspen Plus platform, and the interface between Matlab and Aspen Plus is developed for mutual communication. With the component maps, the Newton-Raphson iteration method is used to solve the thermodynamic performance of the gas turbine.
Based on the above simulation models and solution method, the effects of the mean receiver wall temperature (Ts) and steam-to-methane ratios (R) on the overall performance of the gas turbine are studied in this paper. From the perspective of safe operation, the influence of Ts and R on the net output power of the gas turbine is first calculated. The results show that in the safe operating range, chemical recuperation can significantly increase the net output power of the gas turbine, while the net output power increases first and then decreases with the increase of Ts. When the output power is constant, increasing Ts or R both can effectively reduce fuel consumption, and increasing R can also improve the heat recovery efficiency and the overall thermal efficiency. However, the heat losses of the receiver increase as Ts increasing, meanwhile, the heat recovery efficiency and the overall efficiency also decrease gradually. Therefore, in actual operation, various factors should be taken into account in order to reduce fuel consumption and improve the overall thermal efficiency.
Stochastic Fatigue Life Prediction Based on a Reduced Data Set
Authors: Celli Dino , Shen M.-H. Herman , Scott-Emuakpor Onome E. , Holycross Casey M. , George Tommy J. 
Published: November 2019

Abstract
The aim of this paper is to provide a novel stochastic life prediction approach capable of predicting the total fatigue life of applied uniaxial stress states from a reduced data set reliably and efficiently. A previously developed strain energy-based fatigue life prediction method is integrated with the stochastic state space approach for prediction of total cycles to failure. The approach under consideration for this study is the Monte Carlo method where input is randomly generated to approximate the output of highly complex systems. The strain energy fatigue life prediction method is used to first approximate SN behavior from a set of two SN data points. This process is repeated with another unique set of SN data points to evaluate and approximate distribution of cycles to failure at a given stress amplitude. Uniform, normal, log-normal, and Weibull distributions are investigated. From the Monte Carlo Method, fatigue data is sampled from the approximated distribution and an SN curve is generated to predict HCF behavior from LCF data.
Analytical Formulation of Friction Contact Elements for Frequency-Domain Analysis of Nonlinear Vibrations of Structures With High-Energy Rubs
Authors: Petrov E. P. 
Published: November 2019

Abstract
In gas-turbine engines and other rotating machinery structures rubbing contact interactions can occur when the contacting components have large relative motion between components: such as in rotating bladed disc-casing rubbing contacts, rubbing in rotor bearing and labyrinth seals, etc. The analysis of vibrations of structures with rubbing contacts requires the development of a mathematical model and special friction contact elements that would allow for the prescribed relative motion of rubbing surfaces in addition to the motion due to vibrations of the contacting components.
In the proposed paper, the formulation of the friction contact elements is developed which includes the effects of the prescribed relative motion on the friction stick-slip transitions and, therefore, on the contact interaction forces. For a first time, the formulation is made for the frequency domain analysis of coupled rubbing and vibrational motion, using the multiharmonic representation of the vibration displacements. The formulation is made fully analytically to express the multiharmonic contact interaction forces and multiharmonic tangent stiffness matrix in an explicit analytical form allowing their calculation accurately and fast. The dependency of the friction and contact stiffness coefficients on the energy dissipated during high-energy rubbing contacts and, hence, on the corresponding increase of the contact interface temperature is included in the formulation.
The efficiency of the developed friction elements is demonstrated on a set of test cases including simple models and a large-scale realistic blade.
Development and Application of Minimum Creep Strain Rate Metamodeling
Authors: Vega Ricardo , Stewart Calvin 
Published: November 2019

Abstract
Numerous minimum-creep-strain-rate laws exist, creating a challenge in determining which is best for a given material database. The objective of this study is to validate the applicability of a “metamodel” and its ability to model the minimum creep strain rate (MCR). A metamodel is a model that can combine and regress into different base models, in this case, seven established MCR models. The metamodel can be exploited using a calibration algorithm to rapidly calibrate the base models. The metamodel contains ten terms and eight material constants (one is a constraint, and another is stress as an input variable). Using the metamodel and calibration software, the user can determine the best MCR model for a given material database. Using the software, the metamodel is calibrated in two approaches: constrained and pseudo-constrained. The constrained approach restricts the metamodel to regress directly into one of the base models, allowing for the base models to be equally calibrated and compared alongside each other. The pseudo-constrained approach freely optimizes all eight of the metamodel material constants; however, the metamodel is modified to include 5 Heaviside function constants that turn on/off sections of the metamodel to increase the statistical-dependencies of the final model. This pseudo-constrained approach has the potential to identify novel MCR models that exist at the interface between the seven base models. Alloy data for 9Cr-1Mo-V-Nb (ASTM P91) was used with a total of 89 points which extended over a total of three isotherms: 600°C, 625°C, and 650°C. The MCR model that best fit the data was the Johnson-Henderson-Kahn model.
Topology and Physical Interpretation of Turbulence Model Behavior on an Array of Film Cooling Jets
Authors: Hodges Justin , Kapat Jayanta S. 
Published: November 2019

Abstract
This study strives to provide a critical review and evaluation of influential constituent components in the two-equation k-ε turbulence model class, which are often employed in large full-fidelity gas turbine simulations in industry. All conjectures made, regarding the turbulence model behavior, will be compared to in-house experimental film effectiveness data from a novel film cooling array configuration. This experimental data set is comprised of high resolution adiabatic film cooling effectiveness measurements throughout two film cooling arrays comprised of diffused film holes of modern shape (streamwise inclination of α = 30°, expansion of Φ1,2,3 = 10°, AR = 3.4, and β = 0° relative to the crossflow direction). The difference between each film cooling array is only a staggered verses inline pattern for the film holes, whereby each has a uniform spacing of X/D = P/D = 8. Local coverage, laterally averaged film cooling effectiveness, and superposition analysis was quantified over a variety of testing conditions (M = 0.5, 0.75, 1.0, 1.5, 2.0, 2.5 at DR = 0.9).
First, rendered quantifications of the anisotropic nature of the turbulence are shown throughout the near-field injection region, by leveraging the Reynolds stresses to form anisotropic-invariant maps. Next, results from k-ε models using a linear, a cubic, and a quadratic constitutive relation are compared. Furthermore, effective and conservative scaling of the production and destruction terms in the turbulent transport equations was performed, within reasonable bounds, and the resulting impact on the adiabatic film effectiveness was quantified. This scaling encompasses the Cε2 coefficient, as well as the Durbin realizibility coefficient used in the turbulent viscosity definition. Finally, various formulations of the turbulent Prandtl number were compared, with the resulting adiabatic film effectiveness observed.