bluuebunny/crossref_metadata_2025_split huggingface dataset:
Enhancing Total Temperature Measurement Accuracy: Calibration Procedures and Novel Two-Wire Probes
Authors: Sánchez de la Rosa Diego , Paniagua Guillermo 
Published: August 2024

Abstract
Total Temperature measurement with thermocouple probes suffers from errors due to heat transfer effects. Two dominant sources of errors are convection and conduction between the thermocouple, the support, and the flow. These effects can be treated in two different categories: the velocity error, created by convection from the internal flow velocity in the probe shield, and the conduction error, involving heat transfer through the wire to the shield and the probe stem due to temperature differences between each component. This paper presents a robust approach to experimentally assess and reduce both errors.
An open jet test stand at the Purdue Experimental Turbine Aerothermal Laboratory is used to evaluate the effects of the velocity error at various Mach numbers. Infrared thermography measurements have been conducted to assess temperature gradients on the probe support during this calibration. With this information, it is possible to correct for conduction errors during the calibration and obtain a recovery factor that is solely dependent on upstream velocity. Recovery factor of 0.94 +/−0.05 for Mach 0.2 and 0.98 +/−0.005 for Mach 0.9 are obtained.
Progress has been made on a two-wire thermocouple approach to address conduction errors in the testing scenario, where IR thermography is not possible. The readings from two wires with different length-to-diameter ratios are used with a novel linear correction method to correct for the flow total temperature. Advances in the design and manufacturing of the probe are presented, facilitating faster design iterations and implementation, and providing full control over the calibration procedures. This method can correct conduction errors within 0.2 K for Mach 0.6.
Analysis of NH3 Powered Turbofan Engine With sCO2 Waste Heat Recovery System
Authors: Andress William , Paniagua Guillermo , Vesely Ladislav , Otto Marcel , Kapat Jayanta 
Published: August 2024

Abstract
In the search for alternative aviation fuels, ammonia shows much promise. The higher density and boiling point of ammonia compared to hydrogen could mean ammonia could be used without a dramatic rethinking of aircraft architecture. Instead, the possibility exists that current aircraft and engines could be retrofitted to use ammonia instead of traditional jet fuel. This paper aims to address the engine aspect of such a retrofit. The open-source Toolbox for Modeling and Analysis of Thermodynamic Systems (T-MATS) is modified to allow for the modeling of ammonia fueled engines and the addition of heat exchangers and other technologies. A thermodynamic cycle model of a baseline ammonia engine is created retaining the turbomachinery maps, duct sizes, nozzle areas, and bleed flow rates from a kerosene engine. This engine is then modified by adding heat exchangers and a supercritical CO2 waste heat recovery (WHR) cycle to produce power for the engine and aid in the preheating of the ammonia. Preliminary analysis is performed to determine the ideal location of heat exchangers to benefit cycle efficiency. This analysis suggests that using the ammonia as a heat sink to intercool and recuperate the engine allows for significant improvements over baseline performance. From there, optimization of the geometry of the added heat exchangers is performed to limit heat exchanger size and minimize engine fuel consumption at cruise. The addition of these heat exchangers allows for a reduction in fuel burn of 3%–9% over the baseline engine. Additionally, the WHR cycle can produce the required 250 horsepower (186 kW) of electrical power for the aircraft and the ammonia temperature is increased from 420°R to over 1400°R (233K to 778K). Investigating the results of the optimization shows that making more substantial changes to engines could allow for further improvements to engine performance past that of a retrofit.
Off-Design Heat Exchanger Modelling for Transcritical CO2 Heat Pump Cycles
Authors: Wolscht Leonhard , Podeur Maxime , Adams Martin , Jacquemoud Emmanuel 
Published: August 2024

Abstract
In previous publications, MAN Energy Solutions discussed the steady-state [1], dynamic modelling and validation of large-scale transcritical CO2 heat pump cycles [2]. The current study focuses on the off-design modelling of heat exchangers and presents new models with the aim of capturing the performance of a sea water heat pump subject to large variation in operating and boundary conditions following seasonal variations.
This study shows the impact of novel heat exchanger models on overall heat pump performance throughout its operating envelope as well as on the boundary of the latter restricted by components limitation such as the motor envelope or compressor surge. This allows the identification of the most impactful heat exchanger performance parameters on the overall cycle performance, namely the evaporator and gas cooler HTC. Both steady and unsteady model predictions are validated against manufacturer data and show a relative difference below 1% and 3% for respectively the duty and pressure drop prediction, illustrating the capabilities of off-design models. Moreover, the dynamic modelling of a shell- and tube evaporator is presented and depicts the impact of heat source temperature variation on the evolution of the refrigerant level and its performance. All the above findings contribute to providing reliable and efficient heating and/or cooling services in a wide range of process conditions.
Verification of an Adjoint Code for FGM Combustion
Authors: Duranti Stefano , Jones Dominic , Zhang Yongzhe , Goldin Graham 
Published: August 2024

Abstract
The adjoint method efficiently computes the sensitivity of a global output objective function, such as a combustor outlet temperature uniformity or NOx emission, with respect to a large number of input design variables, such as the centroids of the wall boundary faces. This sensitivity gradient can be used in an optimization algorithm, in particular for shape or topology design to extremize the objective function. In this work, the adjoint model in Simcenter STAR-CCM+ is extended to the Flamelet Generated Manifold (FGM) combustion model. The discrete adjoint is solved by differentiating the linearized flow solver using Automatic Differentiation, transposing these operations, and executing the code in the reverse order. Since the code is complex with a large number of interacting models, a careful verification is required to ensure that the important parts of the code are differentiated properly, and the order of code execution is correct. A global sensitivity for a simple mixing layer flame is compared for forward derivatives (tangent mode), reverse derivatives (adjoint mode) and finite differences. Despite vastly different code path execution for adjoint, tangent and finite-difference, the close agreement of various objective function calculations verifies the correct implementation of the adjoint and tangent code.
Mapping Temperatures on Turbocharger Bearing Cartridge Assemblies Using Thermal History Paints
Authors: Hickey Jim , Kaspschik Nestor , Albrecht Eva , Fischer Christian , Wendel Oliver , Rode Martin , Araguas Rodriguez Silvia , Karagiannopoulos Solon , Feist Jörg 
Published: August 2024

Abstract
In this study, temperatures were mapped on four off turbocharger bearing cartridges, each subject to four different gas-stand tests using Thermal History Paints (THPs). The temperature maps were used to inform initial axial end play settings (and resulting mounted end play) for proper turbocharger performance. THPs are ceramic-derived sensor coatings doped with a lanthanide ion, giving the THP luminescent properties. Exposure to temperatures permanently alters the THP’s luminescent properties. Therefore, by optically probing the THP across the painted bearing cartridge surfaces to trigger its luminescence, historic maximum exposure temperatures maps were evaluated.
Each gas stand test was devised to test each cartridge to the most severe temperature conditions the turbocharger was expected to be exposed to, including one with a heat-soak without water cooling. The tests lasted at least 15 minutes to ensure the cartridge assemblies were fully heat-soaked. THP measurements were taken across pre-determined surfaces of the inner rings and outer ring of all cartridge assemblies. The THP measurement point pitch was 1 mm, providing a unique insight into the historic thermal maps across the cartridge surfaces.
The THP temperature mapping had excellent coverage across each cartridge assembly surface. Some THP detachment occurred, especially on the edges of the inner and outer rings and close to the bearing racers. The THP was especially manufactured for this project to measure lower temperatures (&lt; 200 °C), but this was at the expense of THP durability and adherence.
As expected from the thermal profile of a turbocharger, the turbine-side inner ring was the hottest for all cartridge assemblies. The compressor side inner ring, and outer ring were the coolest. Notably, the outer ring temperature gradient was low, providing confidence in the overall cooling conditions of the cartridge assemblies. The end play of the turbocharger is driven more by the thermal expansion of the outer ring rather than the inner ring. As such, knowledge that it remains cool throughout the test helps inform setting the most appropriate axial end-play clearance.
Partitioned Coupled Heat Transfer Fluid-Structure Interaction for Transient and Steady State Analysis of Aero Engines Applications
Authors: Israel Ute , Cottier Francois , Gier Jochen 
Published: August 2024

Abstract
Designing future gas turbines needs sufficiently accurate methods for determining the temperature distribution parts under high mechanical and thermal loads. Furthermore, to calibrate analytical thermal models with engine test data, which is an important step in the development process, strong engineering judgement and experience is required, and generally an extensive iterative process is needed to reach the predefined matching quality. Coupled simulations can significantly improve quality of conjugate heat transfer calculations and reduce the thermal matching effort. A method for strong aero-thermal coupling for specific demands of aero engine heat transfer is presented. It is based on a partitioned approach designed to integrate standard processes, methods and tools (like mapping methods and solvers) for industrial applications. An efficient approach to take the interaction of the material with the convecting fluid into account is to embed stationary CFD analysis in a flight mission calculation. This enables much fewer steps than necessary for a monolithic coupling like CHT and therefore saves computational effort.
The presented multi-fidelity approach includes strong system coupling of 1D, 2D and 3D models.
A high pressure compressor of a real aero engine has been thermally investigated using the reported coupling method. CFD was used in the rotor drum cavity and standard thermal modeling with FEM for the solid parts combined with flow network/correlations for the low fidelity flow areas. Steady state calculations for high and low loading cases and a transient acceleration were performed. The results are compared with measurements via a calibrated standard thermal model.
Gaseous and Particulate Emissions of an Allison 250-C20B Turboshaft Engine Running on HEFA-SPK and its Jet A-1 Blends
Authors: Rabl Alexander , Rohkamp Marius , Saraji-Bozorgzad Mohammad Reza , Helcig Christian , Sallinen Reetu , Vilja Jesse , Bendl Jan , Adam Thomas , Hupfer Andreas , Gümmer Volker 
Published: August 2024

Abstract
Aviation is widely recognized as a significant source of air pollutant emissions, encompassing gaseous products such as CO2, CO, NOx, and particulate matter (PM), especially in the form of soot. This study conducted comprehensive emission measurements on an Allison 250 C20B turboshaft engine to investigate sustainable aviation fuel (SAF) impact on emissions. Two conventional Jet A-1 fuel blends with 30% and 50% HEFA-SPK synthesized paraffinic kerosene derived from hydro-processed esters and fatty acids (HEFA-SPK) content together with 100% HEFA-SPK were tested regarding their emissions and compared against neat Jet A-1. The study’s primary focus was quantifying ultrafine particulate matter in terms of number and size. The selection of distinct engine power settings was based on the thrust ratios specified in the International Civil Aviation Organization’s (ICAO) Landing and Take-off-cycle (LTO-cycle). PM emissions were characterized using multiple measurement techniques. These included the application of two distinct electrical mobility analyzers. An additional concentration particle counter (CPC) was utilized to underscore the reliability of the findings. A standard FTIR/O2/FID system was used to assess gaseous emissions, a well-established method for measuring fundamental combustion products such as CO2, CO, unburned hydrocarbons (UHC’s) and NOx. The particle measurement systems revealed a decrease in both the number and size of particles with increasing HEFA-SPK content. This decrease in particle number appeared linear for the 30% and 50% HEFA-SPK blends and was more pronounced for the 100% HEFA-SPK. Furthermore, a more substantial reduction in PM emissions, reaching up to 82%, was observed at lower load settings, such as Ground Idle (GI), compared to higher load settings like Take-Off (TO), where the reduction was up to 40%. Results of the gaseous emissions are also presented in the study.
Modeling Combustor Turbine Interaction Using Efficient Joint Simulation Strategy
Authors: Verma Ishan , Zori Laith , Basani Jaydeep , Kamrath Benjamin , Brandt Dustin 
Published: August 2024

Abstract
Computational modeling of hot streak migration in gas turbines is challenging due to multi-scale physics and dynamic interaction between the combustor and the high-pressure turbine (HPT) first stage. The standard practice for modeling such interactions has been performing a 1-way transfer of boundary conditions from the combustor exit to the turbine inlet. This approach is simple but not ideal for capturing the intricate flow perturbations that travel across the components and, hence, not suitable for accurately predicting hot streak migration. An improvement on the standard practice is to conduct separate component simulations and use a 2-way boundary-condition exchange process, which we call co-simulation. In co-simulations, the information between the combustor and the HPT is exchanged in an iterative loop until convergence is achieved. The co-simulations are performed on the hot section of a Honeywell turbofan engine using Stress Blended Eddy Simulation (SBES) in the reversed flow annular combustor and Reynolds Averaged Navier Strokes (RANS) in the HPT.
However, the most accurate combustor-turbine interactions are modeled using joint simulation in which the combustor and the HPT stage are in the same computational domain. Therefore, the joint simulation process excludes the need for any boundary condition exchange. The SBES turbulence model, Flamelet combustion model, and discrete phase-based spray model are applied to the entire domain. Inherent to joint simulations, the transient HPT calculations require the time scale to be that of HPT, which is generally one order of magnitude lower than the combustor time-scale. As a result, joint simulations are computationally very costly (in most situations, prohibitive) compared to co-simulations. In this paper, the computational viability of joint simulations, as a better alternative to co-simulations, is explored using a mixing-plane interface in the HPT. Such an approach ameliorates the disparity in time-scale between the combustor and rotor, which is observed in calculations of joint simulations. As the calculations in joint simulations are performed at combustor time-scale, the overall process hence becomes computationally faster than co-simulations.
The hot streak migration in the HPT is modeled by using a separate simulation of the HPT with sliding mesh (advanced at rotor time-scale). The aero-thermal flow solution and hot-streak migration in the HPT stage are compared between the 1-way transfer, co-simulation, and joint simulation. The distribution of near-wall blade temperatures (instantaneous, period-averaged, maximum, and minimum) is analyzed.
Development of a Transonic Fan Research Facility Focused on Casing Treatments and Inlet Distortion Effects
Authors: Cusator Andrew C. , Brown William J. , Dai Yuning , Bedke Andrew M. , Key Nicole L. 
Published: August 2024

Abstract
Inlet distortion, stall margin enhancement, and aeromechanic excitations such as flutter and forced response are important issues for modern day fans. These topics are often studied both experimentally and computationally. While computational models continue to advance, these issues often require time-accurate or coupled fluid-structure interactions, which can be computationally expensive. Thus, there is a need to have experimental data at engine-relevant conditions so that computational models can be developed and validated. These research topics were the motivation behind the design, build-up, and commissioning of a new fan research facility. The fan hardware, which was donated by Honeywell Aerospace, consists of an 18 in (0.46 m) transonic rotor with 22 blades and 53 stator vanes. At the design speed (near 19,000 rpm), the tip speed is approximately 1,500 ft/s (457 m/s). Power is supplied by a 3,000hp (2.2 MW) motor, and fan power is evaluated using a torquemeter and mass flow rate measurements. The mass flow rate through the machine is measured upstream of the fan with a bellmouth flowmeter, and the flow is throttled downstream of the stators. Since the rotor is representative of a small turbofan engine, the flow splits downstream of the stator for the core and bypass exhaust, and each can be independently throttled to control bypass ratio. The baseline aerodynamic performance of this research article was evaluated to lay the groundwork for future studies.
Techno-Economic Optimisation of Gas Compressor Station Location As a Decision Variable
Authors: Ojo Oluwatayo Babatope , Igie Uyioghosa , Pilidis Pericles 
Published: August 2024

Abstract
An economical natural gas transportation will require the lowest possible capital and operating expenditures over its lifecycle. To attain these conditions, the designers and investors must estimate the number of compressor stations (CS) that are needed along the pipeline route. More so is the need to determine their optimised locations at various pipeline segments along the pipeline. This study considers the techno-economic optimisation of the compressor station and pipeline segments, making up the proposed Trans-Saharan Gas Pipeline (TSGP) project. The optimised lifecycle cost, CS locations and pipeline segments are evaluated with the main aim of minimising costs. A SIMULINK model is developed using the techno-economic and environmental risk analysis (TERA) framework. The model is incorporated with an optimiser that enables an economic analysis of the TERA framework. Including the optimiser affects the outcome of the TERA in terms of the lifecycle cost. The optimisation problems are formulated considering the compressor station location as the decision variable. The lifecycle cost of the compressor stations and pipeline system is the objective function. A scenarios-based techno-economic optimisation study is performed to mimic the standard compressor station and pipeline system network configurations in the real world. The baseline case consists of 18 compressor stations at fixed locations along the pipeline route.
The results show 12 compressor station locations along the pipeline route with a reduction in the lifecycle cost by 12.95% in one of the optimised scenarios compared to the baseline case. The net present value is $28.77 billion assuming a discount rate of 15%. The optimised compressor station locations are at 1, 38, 76, 113, 150, 186, 222, 260, 296, 332, 368, and 408 segments of the pipeline. The outcome of the analyses shows the importance of the two-level optimisation algorithm utilised by the SIMULINK model for the integrated TERA. Hence, this study shows the potential of the TERA modelling and CS location optimisation method utilised in this research in guiding decision-makers on the selection of compressor-turbine configurations. These configurations will give the optimal lifecycle cost at the optimised compressor station locations along the pipeline route.
A Numerical Study of Emission Characteristics in Bluff Body Stabilized Turbulent Premixed Methane-Air Flames in Confined Environments
Authors: Girdhar Anant , Kalathoor Sriram P. , Jagoda Jechiel , Sankar Lakshmi N. 
Published: August 2024

Abstract
Emissions and blow-off are two of the most pertinent issues in the operation of gas turbine combustors. Typical combustors are operated heavily fuel lean to optimize performance. As a result of this, lean blow-off (LBO) becomes an important phenomenon to address. Leaner combustors are cleaner in terms of emissions. However, finding a good operating regime between fuel-lean conditions and allowable emissions can be complicated. This problem is further exacerbated due to turbulent combustor operating conditions. Simulating these problems requires high enough fidelity to capture the detailed flame dynamics and emission profiles. In this study, we reduce this problem to study emission profiles of very lean methane-air flames in a bluff-body stabilized combustor at conditions similar to those studied by Pathania et al (2019). Large eddy simulations are performed using OpenFOAM (an open source, fully compressible reacting flow solver). Two chemical kinetic models — the reduced 17-species and 73-reaction model by Sankaran (2007) and the detailed GRI 3.0 model — are compared in their ability to capture CO emissions in a confined environment. The turbulent Reynolds number associated with the bluff-body flameholder diameter is 38,000. The combustor operates in ambient conditions with no inlet preheat. Simulations are carried out over a computational domain of 4.5 million grid points, and the dynamic k-equation model is used to compute sub-filter stresses. Various flow-flame dynamics are analyzed to assess characteristics such as heat release rates and emission profiles. A comparative analysis of flow field regions (such as upstream, recirculation/flameholding and downstream regions) and their turbulence properties is done. A comprehensive assessment of the spatio-temporal evolution of key intermediate species is also carried out for both models. Finally, the reasons for their respective behaviors and effects on CO production are discussed.