bluuebunny/crossref_metadata_2025_split huggingface dataset:
Numerical Demonstration for a Novel Design of High-Temperature Turbine Facility Enabled by Shock Tube
Authors: Fang Yizhi , Zeng Wei , Ma Haiteng 
Published: August 2024

Abstract
Reproducing the working environment of a gas turbine blade in laboratory has long been a challenge in the state of the art, but is crucial for scaling data from laboratory conditions to engine design point. Specifically, simultaneous matching of Reynolds number, Mach number and turbine inlet temperature in laboratory to those of engine design condition is scarcely achieved in the academic community. As an attempt to tackle this challenge, this paper introduces a novel design of high-temperature turbine cascade, whose mainstream gas is sourced from a shock tube so that high-enthalpy environment is fulfilled. To examine the feasibility of the rig design in obtaining reliable heat transfer data, numerical simulations are conducted, verified and validated against experimental data. Numerical results demonstrate that the new rig is able to produce a mainstream gas of 589±1 K for a test time of 9.5 ms. Nusselt number obtained during the test time agrees well the experimental data in VKI’s isentropic light piston tunnel. Besides, the test duration is sufficient for a steady boundary layer to establish. Furthermore, the new rig is shown to generate a total temperature of 1810±10 K at the cascade inlet for a test time of 1 ms. However, pseudo shock wave forms under this circumstance, greatly augmenting turbulence intensity at the cascade inlet and leads to an over-predicted Nusselt number compared to the experiment. Control of turbulence intensity at the cascade inlet (shock tube outlet) is required as a scope of the future work.
A Perspective on the Process and Turbomachinery Design of Compressed Air Energy Storage Systems
Authors: Maffulli Gianfranco , Grimaldi Angelo , McGillis Andrew , Succi Lorenzo , Przybytko Przemyslaw , Maceli Nicola , Brown David , Brook Graham , Earle Scott 
Published: August 2024

Abstract
The present paper will describe the Baker Hughes experience in the development of the turbomachinery equipment for Hydrostor’s Advanced Compressed Air Energy Storage A-CAES system.
At the core of a CAES plant there is an air compressing system, followed by an air expander used to recover the stored energy.
To achieve a reliable and effective solution, the expander is obtained from the architecture of Baker Hughes steam turbines, which was adapted to match the specific process needs. The criticalities that were addressed and solved to derive the expanders from the original steam turbine are presented.
Specifically, the paper describes the activities performed to optimize the inlet and exhaust sections of each segment, the development of the blades for high atmospheric volume flow, and the implications that thermal transients have on the machine reliability.
The inlet and exhaust sections were arranged according to the layout constraints, which were set to mitigate the effects of the thermal stresses and to reduce the weight to facilitate the machine transportation, while maintaining high aero-performance. As for the expander, a single-body configuration was selected to optimize capital expenditures and reduce leakage to atmosphere.
A new set of blades derived from Baker Hughes’s Steam Turbine stages were developed. This new stage is characterized by rotating blades with high radius ratio; therefore, an optimization strategy was adopted to include the mechanical constraints from the beginning of the design cycle and obtain a final geometry that can be used with different flow path and operating conditions. Finally, the 3D full Navier Stokes Computational fluid dynamics analysis was used to assess the performance of the new stages in nominal and off-design conditions.
A detailed analysis of the thermal transient of the expander parts with FEA methods was performed to assess the life expectations of the equipment. The FEA results are discussed in the paper to show the capability of the machine to sustain an extremely fast start up sequence.
Compressor train is characterized by a multiple body configuration. A detailed optimization was performed to improve the efficiency and the availability of the selected solution. The low-pressure axial compressor discharge section has been optimized to reduce losses and a detailed study of rotor has been performed to evaluate the capability to withstand a high number of start and stop cycles.
Residual Stress Optimisation for Manufacturing of a Nozzle Guide Vane in Mar-M-509 by Laser Powder Bed Fusion
Authors: Lani Sébastien , Pardhi Yogiraj , Ghasemi Hossein , Reinert Felix , Burn Andreas , Soothill Charles 
Published: August 2024

Abstract
This paper delves into the potential of Additive Manufacturing (AM) technologies, focusing on the utilization of Laser Powder Bed Fusion (LPBF) to optimize the manufacturing process for Mar-M-509, a Cobalt-based superalloy, in aeroderivative industrial gas turbine nozzle guide vanes. While Mar-M-509 offers exceptional properties for high-temperature applications, the rapid cooling rates inherent in LPBF introduce significant residual stresses, leading to poor success rates below 50%.
The study systematically addresses this challenge by proposing a comprehensive methodology to optimize LPBF parameters. By fine-tuning processing conditions, including elevating the powder bed and build chamber temperatures, the research achieved notable reductions in residual stresses by up to 55%. Computational simulations played a pivotal role in predicting deformations and thermal signatures, enabling proactive adjustments to process conditions, ultimately enhancing part quality and process reliability.
Validation through successful printing with a yield exceeding 75% underscores the effectiveness of this approach. Moreover, the study suggests the broader applicability of these optimization strategies beyond Mar-M-509, paving the way for advancements in AM techniques across diverse materials and industrial sectors.
This research not only presents a robust solution for mitigating residual stresses in LPBF-produced components but also showcases a proactive methodology that promises significant implications for additive manufacturing’s future advancements and applicability.
Unsteady Pressure Behavior on Blade Surface Induced by Wake-Blade Interaction in an Axial Compressor Stage
Authors: Zheng Xuedong , Wang Baotong , Li Jia’an , Yan Chuanxiang , Zheng Xinqian 
Published: August 2024

Abstract
Wake from upstream blades is a significant vibration excitation source in axial compressors. One needs to know how wake passing induces the unsteady pressure to design a more efficient and reliable compressor. This paper studies the pressure fluctuation caused by the wake of the upstream stator of an axial compressor stage using full annulus unsteady RANS (URANS) calculation. Wake-induced excitation is much stronger than downstream potential excitation and is more significant on the blade pressure surface. Along the chord length, near the leading edge, the noticeable unsteady pressure disturbance comes from a nonlinear interaction and propagates at 57% speed of the wake convective speed on the blade suction surface. The unsteady pressure at the suction and pressure surfaces are out of phase, which is believed to be induced by the incidence change from the negative jet effect; At the mid-chord, there are apparent unsteady pressure propagation patterns on both the pressure and suction surface, which are influenced by the blade number of rotor and stator. Moreover, the original case has a lump-shaped pressure disturbance distribution and propagates upstream. With the blade number changed, an obvious linear pressure wave pattern emerges, which is related to the cut-on/off condition between S0 and R1. When wake impinges on the downstream blade, the induced pressure disturbance will further cause the unsteady pressure fluctuation on the neighbor blade suction surface in the same row.
Based on these phenomena, it is concluded that the wake will input energy to the blade more efficiently through the leading edge. A large vibration amplitude near the leading edge should be avoided. Furthermore, reducing the leading edge separation bubble may mitigate the excitation. More importantly, the result indicates the nonlinear interaction induced by wake mainly happens near the leading edge, and the pressure interaction in the blade passage is almost linear.
Speed Strategy on High-Pressure Compressor for the Charging Process of Advanced Adiabatic Compressed Air Energy Storage During Dynamic Shutdown
Authors: Wang Yi , Qin Guoliang , Jia Cheng , Cui Qin 
Published: August 2024

Abstract
Advanced adiabatic compressed air energy storage (AA-CAES) starts and shuts down frequently. The default operation of the high-pressure compressor (HP) connected to the cavern is to reduce the speed of the inverter motor during shutdown. Whether or not the default speed strategy is safe has yet to be focused on. To this end, a detailed charging process comprising three series of centrifugal compressors with intercoolers was constructed within the framework of UniSim® Design. The safety measures were meticulously considered by integrating anti-surge circuits, vent valves, and check valves. PI controllers were allocated to the primary component to govern the shutdown procedure. The speed strategy of the HP inverter motor during the load shedding stage is the focus of research. Six speed strategies, including decreasing speed, constant speed, and increasing speed, were discussed, respectively. The discussion focused on changes made to air injection, inlet mass flow of the HP, inlet and outlet pressure of both the middle-pressure compressor (MP) and HP, and energy efficiency. The study found that implementing the minimum allowable speed for the inverter motor speed (IMS) and increasing speed during the load shedding stage can cause fluctuations in the air injection. As IMS increases at the end of the load shedding stage, the pressure anomalies at the MP outlet and the HP inlet weaken, and the shutdown process’s energy efficiency improves. The HP inlet flow fluctuations caused by various strategies were within an acceptable range. This study reveals that there is a mutual influence between components in the charging process of AA-CAES. An appropriate speed strategy for the HP inverter motor can mitigate the operational hazards. The results of this study can provide guidance for similar AA-CAES shutdowns.
Performance of Rough-Ribbed Low-Pressure Turbine Blades Under Varying Loading and Operating Conditions
Authors: S. M. Ananth , Nardini Massimiliano , Kozul Melissa , Vadlamani Nagabhushana Rao , Sandberg Richard D. 
Published: August 2024

Abstract
Recent research have demonstrated the effectiveness of riblets (streamwise aligned grooves) in reducing the profile loss of low-pressure turbine (LPT) blades under high-lift loading. In this research, we pursue the efficacy of riblets in reducing the blade profile loss under various design and off-design conditions. We adopt a strategy in which surface roughness is employed in the transitional regime to minimize the separation bubble-related losses and flush mounted riblets downstream to further mitigate the skin-friction drag and boundary layer losses due to an increase in the turbulent wetted area (TWA). Several high-fidelity scale resolving simulations are carried out to test the efficacy of this ‘rough-ribbed’ LPT blade for loadings ranging from low-lift (LL), high-lift (HL) and ultra high-lift (UHL) conditions. Furthermore, two exit Reynolds numbers - 83,000 and 166,000 pertaining to engine relevant design and off-design conditions, respectively, are considered. The streamwise evolution of skin-friction coefficient and boundary layer integral parameters are compared and contrasted among different test cases. The instantaneous flow features and second order statistics such as the Reynolds stress and turbulent kinetic energy are analyzed to determine the design and off-design performance of riblets. It is found that the efficacy of scallop-shaped riblets in reducing the profile loss improves with loading. Specifically, the net skin-friction reduction increases from 3.4% under LL to 8% under UHL loading at cruise Re. There is a corresponding reduction in the trailing edge momentum thickness (θTE) from 10% to 15%. A further reduction in θTE is attained from design to off-design Re under UHL loading. Thus the effect of riblets in reducing mixing losses improves with increasing Re. It is also found that the riblets reduce flow blockage due to boundary layers. Furthermore, the necessity to optimize riblet ramp to achieve skin-friction reduction under off-design conditions is highlighted.
Development and Validation of an Isolated Unsteady Diffuser Computational Model for a Vaned Centrifugal Compressor
Authors: Holtmann Benjamin , Shapochka Mark , Key Nicole 
Published: August 2024

Abstract
Recent advancements in computational technologies have greatly increased their ability to be applied to complex problems in aeroengine design. Computational Fluid Dynamics (CFD) is being applied to increasingly complicated systems, including centrifugal compressors, which are known for complex flow structures due to the compound curvature inherent in the flowpath. Modeling these flow fields is normally accomplished using mixing planes between the impeller and the diffuser, which are convenient due to their quick convergence and turnaround time needed for design iterations. However, the simplification of circumferentially uniform flow entering the diffuser of a centrifugal compressor may lead to incorrect design choices. In fact, the jet-wake characteristic of the impeller exit flow field leads to significantly unsteady nonuniform flow entering the diffuser.
While incorporating unsteady effects allows for greater accuracy, it is frequently not practical to run full-stage, unsteady simulations due to the significantly increased computational cost, especially when conducting multiple design iterations. Thus, the motivation of this paper is to develop a simplified diffuser model that incorporates unsteadiness from the impeller flow field without requiring a full-stage unsteady CFD simulation. Steady and unsteady isolated-diffuser computational models were developed for a vaned centrifugal compressor, which reduced the computational cost of unsteady CFD simulations, when compared to full-stage unsteady models. The isolated unsteady diffuser model used unsteady inlet boundary conditions from a full-stage, unsteady model. The model was validated with laser Doppler velocimetry (LDV) test data gathered from the Centrifugal Stage for Aerodynamic Research (CSTAR) facility in the High-Speed Compressor Lab at Purdue University. Validation of the isolated unsteady diffuser model showed it consistently performed similarly to the full-stage unsteady model when predicting total pressure, absolute velocity magnitude, and incidence. Additionally, both models closely matched LDV test data. Incidence at the shroud-side diffuser leading edge was still overpredicted. These results show promising signs of the isolated unsteady diffuser model to solve preliminary concepts in parallel, with good accuracy, before evaluating best performing ones in a more costly and high-fidelity, full-stage unsteady CFD model.
Evaluation of Data-Driven Classifiers for an Ignition Forecast of Large Gas Turbines
Authors: Lang Florian , Savtschenko Maximilian , Yadav Vikas , Ghani Abdulla 
Published: August 2024

Abstract
This paper demonstrates several supervised learning algorithms for ignition prediction of large stationary gas turbines (GTs), based on existing “real world” operational data. We obtain the data set from the mature SGTx-8000Hframe. In this work, we detect both successful and failed ignitions in advance based on various environmental changes. We test seven classification algorithms for their classification ability in the context of engine ignition: Random Forest (RF), Balanced Random Forest (BRF), Gradient Boost (GB), Gaussian Process Classifier (GPC), Multiple Logistic Regression (MLR), AdaBoost and Support Vector Machine (SVM). After a detailed pre-processing including data selection, cleaning and feature engineering, the modelling results are promising: The small fraction of 2% failed ignitions, in the presented data set, is correctly classified with high accuracy. In addition, we reduced the parameter space from 22 to 11 (for the fleet’s 60 Hz cohort) and to 14 (for the fleet’s 50 Hz cohort). In a further step, we reduced to 5 and finally to 2 features while maintaining the model’s accuracy, which boils down the model complexity by the application of 2 robust selection methods: The Pearson’s paired comparing of feature correlation and the Recursive Feature Elimination (RFE).
Starting with seven applied classification algorithms on the whole GT fleet’s data set (both 50 Hz and 60 Hz cohorts) we reduced the data set length to a single engine and applied the most promising classifiers accordingly. To check the “real world” applicability and thus the classifier’s performance on unseen data, we apply two different test scenarios: Firstly, we transfer the prediction map for successful ignitions of a 50 Hz GT with good accuracy to unseen data of a different 50 Hz GT. Secondly, we assist the commissioning engineers for the recommissioning after an overhaul of a 60 Hz GT. The algorithm’s recommendation led to constant successful ignitions on this specific test site covering various boundary conditions over the observation period of 2 years.
Performance Analysis of a Self-Decarbonizing Combustor
Authors: Akojwar Kartikeya S. , Pawar Samadhan A. , Chaudhuri Swetaprovo 
Published: August 2024

Abstract
Hydrogen is envisioned to be a key decarbonization solution for fossil fuel-dependent power generation and aviation industries. At present, a significant fraction of the generated electrical power is derived from natural gas. As such, the external energy needed for hydrogen generation, often sourced from fossil fuels, results in CO2 emissions, compromising overall carbon neutrality. Instead, the processes of hydrogen generation can be energetically coupled with the combustion process, in-situ, to eliminate external energy requirements. To that end, a novel self-decarbonizing combustor has been conceptualized, integrating methane pyrolysis with the combustion process that can in principle decarbonize many contemporary power generation technologies. The underpinning methane pyrolysis process enables in-situ pre-combustion capture of solid carbon. Consequently, CO2 emissions resulting from the combustion of processed, hydrogen-enriched fuel are mitigated. This study provides a comprehensive analysis, delineating the operating principle and the effect of some of the important governing parameters on the performance of the self-decarbonizing combustor. These parameters including fuel temperature, residence time, pressure, and catalysis are studied in the context of potentially applying the proposed concept to natural gas-based decarbonized electrical power generation. Investigating fuel chemistry, combustion exhaust, carbon structure and morphology under varying process parameters enhances our comprehension of this prospective technology. Additionally, the self-sufficient nature of the system, eliminating the need for separate hydrogen production, storage, and transportation infrastructure, highlights its potential as a scalable and achievable technology.
Experimental and Numerical Investigation of the Counter-Rotating DLR Turbo Fan Stage CRISPmulti With Boundary Layer Ingestion
Authors: Lengyel-Kampmann Timea , Charroin Guillaume , Meyer Robert 
Published: August 2024

Abstract
Boundary Layer Ingestion (BLI) has gained significant attention as a potential aerodynamic concept for improving the performance and efficiency of modern aircraft. It can significantly reduce the total pressure losses and, as a result, increase the propulsion efficiency of the engine. Enhanced propulsion efficiency leads directly to reduced fuel consumption [1,2]. Besides these above-mentioned benefits, the BLI has also some undesirable effects, like inhomogeneous inflow in the engine intake. This distorted inflow interacts with the rotating blades, which leads to increased blade vibrations, additional noise sources and unfavorable aerodynamic properties [3,4,5]. This study investigates the impact of BLI on the characteristics of the fan, focusing on pressure, temperature and velocity field. The comprehensive investigation of the application of BLI through a combination of experimental and numerical approaches to assess its influence on the fan behavior is presented in this paper.
On Intake-Compressor Interactions Within an Integrated Propulsion System
Authors: Rademakers Rudolf P. M. , Stößel Marcel , Kožulović Dragan , Niehuis Reinhard 
Published: August 2024

Abstract
The integration of a propulsion system into the airframe can contribute to the overall aircraft performance and is beneficial for military applications due to a reduction of the aircraft radar cross-section. On the other hand, engine integration calls for serpentine engine intake systems in which generally combined pressure-swirl distortions are provoked, which affect the performance of the propulsion system. The Military Engine Intake Research Duct (MEIRD) was designed to provoke a large-scale flow separation as well as a combined pressure-swirl distortion. The serpentine research duct is tested in both a remote- and close-coupled setup with the Larzac 04 turbofan engine to assess the aerodynamic interactions between the flow within the intake duct and the compression system. The upstream effect of the compression system on the steady-state duct flow is within the range of expectations. Less is known from the open literature with regards to the unsteady character of the flow in such a setup. Three distinct unsteady flow phenomena caused by the serpentine shape of the duct are identified up- and downstream of the low pressure compressor in the remote-coupled setup. An additional distinct low frequency unsteadiness is provoked with a configuration which features vortex generators for flow control. All phenomena are largely attenuated by the upstream effect of the compressor in the close-coupled setup. Nonetheless, the surge margin is massively reduced due to the inflow distortion and stall cells within the first stage of the low pressure compressor are visualized at high thrust settings of both the remote- and close-coupled setup, which are expected to impact the durability of the compression system.
Film Cooling Effectiveness Measurements on a CMC-Simulated Flat Plate
Authors: Thurman Douglas , Poinsatte Philip 
Published: August 2024

Abstract
Ceramic matrix composites (CMC) are high temperature materials that can allow higher operating turbomachinery engine temperatures with less coolant required. One method of fabricating ceramic matrix composites is by weaving fibers into the shape of an airfoil. Generally, CMC fiber tows are assembled with various weave patterns, but this uneven surface could introduce aerodynamic losses, and it will be necessary to determine the best film cooling hole arrangement for minimal thermal engine efficiency loss. As part of an effort to assess the impact of geometric constraints of CMC implementation relative to metallic high pressure turbine blades, an experimental study was performed to investigate the effect of film cooling on a CMClike surface roughened flat plate. Film cooling effectiveness measurements were acquired on a large-scale surface with a ceramic matrix composite weave pattern and on a smooth surface for comparison. A single row and a 2-row cooling hole arrangement were investigated with different hole sizes. Infrared thermography data was acquired at several Reynolds numbers and blowing ratios. Results showed that the effect on span averaged film cooling effectiveness was small between a weave surface pattern and a smooth surface, while hole spacing dependence had a much stronger effect.