bluuebunny/crossref_metadata_2025_split huggingface dataset:
Experimental Investigation of CH4-Humid Air Flame Characteristic of a Novel Micromix Concept Model Burner
Authors: Liu Ce , Shao Weiwei , Zhang Zhedian 
Published: October 2022

Abstract
The temperature and humidity of the combustion chamber inlet air under the humid air turbine cycle (HAT) vary dramatically, with the highest air temperature of approximately 900 K and high humidity of about 0.3 kg/kg. Compared with conventional lean premixed combustion, which may cause risks such as flashback and autoignition under high-temperature conditions, micromix combustion has the characteristics of small mixing scale, compact flame, flashback resistance, and low emissions, and has been implemented in HAT cycle combustion chambers. In this work, a 9-nozzle micromix model burner with a 3 × 3 array arrangement was designed based on the flow field organization of multiple micromix round jets. The effects of heat load (30∼55 kW), air temperature (300∼630 K), and steam ratio (0∼0.143 kg/kg) variation on the combustion and pollutant emission characteristics of methane-humid air micromix flame at atmospheric pressure conditions were experimentally investigated. Intensified Charge-Coupled Device (ICCD) is adopted to detect OH* chemiluminescence distribution thus investigating the turbulence-reaction interactions and the characteristics of the reaction field. And the effect of humidity on NOx emission was qualitatively analyzed by combining it with a reactor network model. Results indicated that compact flames were achieved for different cases with flame heights of about 85∼185 mm. The steam ratio has a significant influence on the flame structure and NOx emission. Compared with the dry air condition, the flame length increased by nearly 50% while the steam ratio reached 0.143 kg/kg, and the NOx emission was kept at a relatively low level of about 5 ppm (@15% O2) under the designed operating condition. The in-depth understanding of humid air micromix combustion technology is a significant step toward the design of future stability combustors for the HAT cycle.
Simultaneous Ultra-Small-Angle X-Ray Scattering and X-Ray Transmission Measurements of a Liquid Jet in Crossflow With Film Atomization
Authors: Sforzo Brandon A. , Ilavsky Jan , Powell Christopher F. 
Published: October 2022

Abstract
Aircraft atomizers generally rely on multiple physical phenomena to introduce, distribute, and mix liquid fuel with the continuous air flow. Many such devices use plain jets for high liquid flow rates and film shear atomization to encourage droplet formation. To further characterize the near-field of processes, experiments were conducted to examine multiphase development of a liquid jet issuing into a subsonic crossflow. The jet impinged on a wall and the liquid subsequently filmed and convected downstream until reaching the end of the splitter plate, where it broke up by shear forces. X-ray diagnostics were used to interrogate different regions of the flow at the Advance Photon Source at Argonne National Laboratory 9-ID beamline. The projected liquid mass distribution was measured through x-ray absorption correlations using the collimated beam. The light was conditioned for Ultra-Small-Angle-X-ray-Scattering measurements, which were collected simultaneously with the transmission signal. These transmission and scattering signals were used to compute the projected mass and path-specific surface area of the spray, which were combined to calculate Satuer mean diameter. Though the transmission is typically collected using focused beam with a finer spatial resolution during a separate experimental campaign, the near-simultaneous acquisition allowed for more accurate registration between the signals and control of the operating condition. The transmission mapping confirmed the liquid path length of the unbroken liquid jet issuing into the domain and the interaction point with the wall. The spreading and flowing of the liquid down the plate and shedding from the trailing edge of the plate revealed an order of magnitude greater liquid path length, indicating the spreading of the film. X-ray scattering results indicate surface wave formation on the liquid jet and the initial stripping of droplets from the column. Furthermore, the scattering was enhanced for droplets rebounding due to splashing from the plate. The combined signals were used to calculate the droplet diameters in the shear breakup region trailing the splitter plate. These combined measurements provide detailed breakup information to inform inputs required to initialize Lagrangian spray calculations, as well as validate high-fidelity atomization simulations.
The Effect of Gas and Surface Temperature on Cold-Side and Hot-Side Turbine Deposition
Authors: Bons Jeffrey P. , Lo Chihsiu , Nied Eric , Han Jiaxuan 
Published: October 2022

Abstract
Deposition studies were conducted using two impingement jet facilities: a 60m/s cold jet (830–950K) impinging on a heated Hastelloy-X surface (1033–1255K) and a 215m/s hot jet (1450–1625K) impinging on an uncooled ceramic target or a cooled thermal barrier coated (TBC) surface (1090–1400K). These can be considered analogs for an internal impingement cooling jet flow and an external nozzle guide vane leading edge flow respectively. Airflows were seeded with 0–10μm Arizona Road Dust and deposition accumulated over a period of 5–10 minutes. Select tests were completed with other size distributions. Studies were conducted by varying flow temperature at constant surface temperature, and vice-versa. For both the hot and cold impingement jets, the sensitivity of capture efficiency to fluid (and thus particle) temperature was found to be roughly double the sensitivity to surface temperature. Hot jet tests with three different size distributions of dust (0–5, 0–10, and 5–10μm) allowed particle size sensitivity to be evaluated. For both target types (ceramic and cooled TBC), the 0–10μm test dust produced the highest deposition rate of the three size distributions. Possible explanations for the observed behavior are proposed. Companion CFD studies modeling both impinging jets with particle deposition demonstrate that temperature induced variations in particle trajectories alone are not sufficient to explain observed deposition trends with temperature. Implications for the development of a universal sticking model relevant for gas turbine deposition are discussed.
Heat Transfer in a Rotating, Blade-Shaped, Two-Pass Cooling Channel With Various 45 Deg Rib Turbulators and a Tip Turning Vane
Authors: Chen I-Lun , Wright Lesley M. , Han Je-Chin , Krewinkel Robert 
Published: October 2022

Abstract
This work experimentally studied a rotating, blade-shaped, two-pass cooling channel with various 45 deg rib turbulators and a tip turning vane. The first passage of the cooling channel has an aspect ratio (AR) = 4:1 with the coolant moving radially outward. After a 180 deg blade-shaped tip turn, the coolant flows radially inward into the second passage with an AR = 2:1. The first and second passages are oriented at 50 deg and 105 deg from the rotation direction, respectively. In the tip turn portion, a tip turning vane with an oval cross section connects the mid-lines of the two passes. Two orientations of 45 deg angled ribs were considered in this work: unusual, and criss-cross. The ribs have a profiled cross section and were placed in-line (P/e = 10, e/H = 0.16) on the leading and trailing surfaces of the channel. Five inlet Reynolds numbers (10,000 to 45,000) and five rotational speeds (0–400 rpm) were considered in this study, with a maximum rotation number of Ro = 0.38 achieved in the first pass. The results showed that the reduction from the turning vane on heat transfer and pressure loss for the 45 deg unusual rib case was the lowest. The overall heat transfer for the criss-cross rib case was slightly increased by the turning vane. For pressure loss, the turning vane provided approximately 8% reduction in the 45 deg criss-cross rib case, which was the highest in the rib cases. The 45 deg criss-cross ribs presented the highest thermal performance with the turning vane.
Comparing Different Schemes in a Combined Technique of Kalman Filter, Artificial Neural Network and Fuzzy Logic for Gas Turbines Online Diagnostics
Authors: Togni Simone , Nikolaidis Theoklis , Sampath Suresh 
Published: October 2022

Abstract
The paper presents research on the online performance-based diagnostics by implementing a novel methodology, which is based on the combination of Kalman Filter, Artificial Neural Network, Neuro-Fuzzy Logic and Fuzzy Logic. These methods are proposed to improve the success rate, increase the flexibility, and allow the detection of single and multiple failures. The methodology is applied to a 2-shaft industrial gas turbine engine for the automated early detection of single and multiple failures with the presence of measurement noise.
The methodology offers performance prediction and the possibility of utilizing multiple schemes for the online diagnostics. The architecture leads to three possible schemes. The first scheme includes the base methodology and enables Kalman Filter for data filtering, Artificial Neural Network for the component efficiency prediction, the Neuro-Fuzzy logic for the failure quantification and the Fuzzy Logic for the failure classification. For this scheme, a performance simulation tool (Turbomatch) is used to calculate the thermodynamic baseline. The second scheme replaces Turbomatch with the Artificial Neural Network, that is used to calculate the deteriorated efficiencies and the reference efficiencies. The third scheme is identical to the first one but excludes the shaft power measurements, which are not available in aero engines or might not be usable for some power plant configurations.
The paper compares the performance of the three methodologies, with the presence of measurement noise (0.4% reference noise and 2.0% reference noise), and 24 types of random single and multiple failures, with variable magnitude. The first methodology has been already presented by Togni et al. [10], whereas the other two methodologies and results are part of the PhD thesis presented by Togni [18] and they extend the applicability of the method. The success rate, targeting the correct detection of the of the failure magnitude ranges between 92% and 100% without measurement noise and ranges between 66% and 83% with measurement noise. Instead, the success rate of the classification, targeting the correct detection of the type of failure ranges between 93% and 100% without measurement noise and between 85% and 100% with measurement noise.
A Numerical Study on Conjugate Heat Transfer of Supercritical Carbon Dioxide Cooling in a Staggered Pin Fin Structure
Authors: Wardell Ryan J. , Otto Marcel , Smith Matthew , Fernandez Erik , Kapat Jayanta 
Published: October 2022

Abstract
Focused research and development of pin fin geometry in the trailing edge as turbulators in turbine blades has been a subject thoroughly researched for the past several decades. Highly efficient turbomachinery requires higher inlet temperatures, introducing the need for these internal cooling channel features to increase the heat removal of the blades and prevent material failure. Turbomachinery commonly uses air cycles to operate, but recently there has been a shift towards supercritical carbon dioxide (sCO2) power cycles. Promising higher cycle efficiency and smaller footprints, sCO2 has become an attractive alternative to the well-established turbomachinery cycles used presently. This alternative introduces the need to re-visit the local heat transfer of these internal cooling solutions with the incorporation of sCO2 as the cooling fluid. The first objective of this paper is to study the conjugate heat transfer characteristics of sCO2 as the secondary internal cooling fluid, operating at temperature and pressure conditions significantly above the critical point. A new heat transfer correlation is proposed for sCO2 in a staggered pin fin array. Secondly, the resulting sCO2 cases are compared to air cases in a matching staggered pin fin array to investigate the differences and similarities between both working fluids. The steady RANS conjugate heat transfer study was carried out with the commercial computational software STARCCM+ for the sCO2 and air cases. Finally, this study will validate a future experimental rig with matching geometry.
Digital Service Twin to Assess Engine Deterioration and Remaining Part Life
Authors: Klein Markus , Staudacher Stephan , Abu-Taa Kimon , Schwengler Jonas 
Published: October 2022

Abstract
During its complete service life, a turbo jet engine undergoes a continuous change of condition due to environmentally caused deterioration. The description of this change for an individual engine or even a fleet of engines results in a computational challenge requiring tailor-made parallelization. A digital service twin model is presented, which is capable to predict the engine condition on part level at any time of its life cycle. Deterioration is expressed on the level of relevant engine parts, whereby the interaction of multiple damage phenomena can be considered. Changes in component efficiency and capacity are deduced from part deterioration, allowing to map the gradual deterioration depending on its operational conditions. Flights based on Engine Health Monitoring data, ADS-B - data or synthetically created flights are used to run the model. Deviations, which arise due to these different data bases, are discussed. Besides the validation of the digital service twin, a sensitivity analysis is presented for input parameters which are not prescribed by commonly used data bases. This embraces the effects of time resolution, model quality and selected assumptions of unknown input parameters. Finally, the outcome of the digital service twin is presented for a reference deterioration phenomenon.
Root Cause Analysis of the Lack of Market Success of Micro Gas Turbine Systems
Authors: Tilocca Giuseppe , Sánchez D. , Torres García M. 
Published: October 2022

Abstract
Micro gas turbine systems were introduced to the market at the dawn of the twentieth century, with the selling arguments of small footprint, low gaseous (NOx) and acoustic emissions, low maintenance and versatility for high-grade Combined Heat and Power applications. Unfortunately, the technology has enjoyed very limited market success and, currently, its market share for decentralized applications is marginal. Fierce competition by reciprocating internal combustion engines (ICEs), an established technology, has always been identified as the main barrier hindering the market deployment of micro gas turbines.
In this landscape, this work presents a root cause analysis that aims to identify the causes of this weak market penetration of MGTs. It aims to solve a block of the logic tree that represents the end-user choice to adopt one or the other technology. A single Key Performance Indicator is used to combine technical, economic, emission, and operational factors. This KPI is a compound indicator based on several weighted penalty factors and represents an original approach enabling the identification of the potential markets for this technology. The indicator is computed for the range of electrical power outputs in which microturbines compete.
This work compares three different case studies all related to CHP applications. The new methodology confirms the lack of competitiveness of microturbines in market segments without specific heat or emission requirements.
Investigations of the Unsteady Aerodynamic Characteristics for Intakes at Crosswind
Authors: Piovesan Tommaso , Wenqiang Zhang , Vahdati Mehdi , Zachos Pavlos K. 
Published: October 2022

Abstract
The ground vortex generated in front of an intake operating near the ground and subjected to crosswind is investigated using CFD and compared to the experiments. The flow field of a scale-model intake is numerically simulated with both steady and unsteady approach, with the aim of predicting ground vortex effects and to characterize the vortex unsteady behaviour. The experimental results showed that for an intake near the ground under crosswind the ground vortex that forms under the intake and the in-duct separation, when present, exhibit unsteady behaviour that becomes stronger as the crosswind velocity is increased. The simulations indicate that a steady-state approach only partially reproduces the time-averaged ground vortex characteristics and in-duct distortion losses, while an unsteady approach shows a lower level of unsteadiness compared to the experimental observations. The consequences of the unsteady flow in the intake on the fan aerodynamic and aeroelastic stability are finally discussed to reinforce that these can result in significant non-synchronous vibration (NSV) and loss of stall margin which cannot be adequately assessed if no unsteady component of the inlet distortions is taken into account.
FGM Applied to Grid Plate Flame Stabilisers for NOx Prediction in Non-Premixed Gas Turbine Combustion
Authors: Quiñonez Arce José Ramón , Andrews Gordon E. , Phylaktou Herodotos 
Published: October 2022

Abstract
The present work investigates one of the lowest NOx design concepts using directly fueled grid plate flame stabilisers [10] termed Grid Mix (GM). The work uses CFD to predict experimental results for the GM low NOx flame stabilisers operated with propane. An additional study was undertaken to analyse their performance on hydrogen, a zero-carbon fuel at the heart of the UK zero-carbon power generation policy. Combustors are in production using similar technology to GM, and at least two manufacturers have low NOx hydrogen combustors using similar flame stabilisers [9, 18, 21–24]. Also, as the tests were at atmospheric pressure, the results are relevant to process burners, and the test condition for the CFD was a 140 kW thermal input process burner.
The Grid Mix technique for non-premixed combustion, with fuel injected into the airflow at the periphery of the air holes, allows rapid fuel and air mixing for lean non-premixed ultra-low NOx combustion. The technology has been investigated at high entry temperatures of modern industrial gas turbines with all the combustion air passing through the flame stabiliser at a typical reference Mach number for this condition of M = 0.047, at an overall pressure loss of ΔP/P = 2.4%, for a heat release of 28MW/m2. These conditions are well above most experimental and CFD publications on low NOx gas turbine emissions.
The combustion and NOx predictions for hydrogen show that Grid Mix flame stabilisers offer a viable solution to low NOx with hydrogen combustors. In addition, the advantage of adding fuel and air mixing passage downstream of the Grid Mix fuel injector is also demonstrated, as used by Yorke et al. [18].
Influence of Real Gas Properties on Loss in a Super Critical CO2 (sCO2) Centrifugal Compressor
Authors: Cai Ruikai , Yang Mingyang , Deng Kangyao , Zhuge Weilin , Yang Bijie , Martinez-Botas Ricardo , Chen Tao 
Published: October 2022

Abstract
The performance of the SCO2 centrifugal compressor is the key component influencing the efficiency and stability of the whole Close-Bryton cycle system. It is important to understand the loss mechanism inside the compressor to guide the design and performance optimization of the compressor. However, the physical properties of SCO2 are strongly nonlinear near the critical point, and the internal flow of the compressor is highly coupled with its properties, which inevitably profoundly influences the loss generation in the device. In this paper, the loss mechanism of SCO2 compressor is investigated comprehensively based on numerical method compared with experimental data. CO2 real gas model embodied in RANS model are used for the study. Firstly, grid independence and influence of the resolution of real gas properties tables are discussed. The numerical simulation results are in good agreement with the experimental data of Sandia SCO2 compressor. Secondly, the distribution of the loss of the compressor are evaluated by means of local entropy generation at different mass flow rates. In particular, a direction comparison between the cases with real gas properties and the constant properties is carried out for manifesting of the influence by real gas properties. The results manifest that the loss of the case with constant properties is profoundly higher than that of the real gas properties, especially at small flow rate. Detailed flow field is compared to understand the influence of the properties. It is shown that the tip leakage flow is evidently decreased with the real gas properties and results in a much more uniform flow distribution throughout the impeller. The decrease in static temperature and pressure due to the acceleration of SCO2 at the tip of the main blade causes an increase in fluid density, reducing the tip leakage and secondary flow. Moreover, the influence on the flow in the impeller results in smaller incidence angle near hub side for the case with real gas properties, thus the separation on the suction surface which happens in the case with constant properties is alleviated. Therefore, the loss in both the impeller and diffuser is significantly reduced by the real gas properties.
Numerical Investigation Into Maximum Pressure Capability of Intershaft Hydraulic Seals
Authors: Warusevitane Achinie , Johnson Kathy , Ambrose Stephen 
Published: October 2022

Abstract
Hydraulic seals are used as intershaft seals in aero-engines and consist of an oil filled trough on the higher speed shaft and a fin on the lower speed shaft that dips into the oil forming the seal. Rotation is imparted to the sealing fluid within the trough and, similar to a manometer in operation the liquid either side of the fin can be at different heights allowing the seal to withstand differential pressure. In normal operation hydraulic seals do not leak air but if the differential pressure becomes too high the seal will break down and leakage will occur.
There is limited published research relating to hydraulic seals and the accuracy and reliability of the existing design approaches based on analytical derivations is not fully known. This acknowledged need to improve the ability to develop accurate computational models of hydraulic seals provides context for the current study.
An approach to evaluate the maximum pressure capacity of a hydraulic seal is therefore introduced in this work. Building on previously published studies, this paper presents results of a 2D numerical study into the performance of a simplified hydraulic seal geometry. This paper reports a numerical CFD methodology based on an axisymmetric Volume-of-Fluid (VOF) method. In this study there is no oil feed into the trough.
Results are presented for a range of shaft speeds of 2000–8000 rpm for the high speed shaft and 1000–4000 rpm for the low speed shaft. Fin position within the trough was varied. A criteria for broken seal was developed. The CFD data shows that the seal can withstand higher pressure at higher shaft speed with the characteristic following the expected linear relationship between differential pressure and shaft speed squared. The seal could withstand a higher differential pressure if the fin was closer to the housing on the high pressure side with this being attributed to the secondary air flow in the cavity.
The average core velocity was compared to values obtained using different analytical approaches and it was found that one where core angular velocity is proportional to the area averaged rotational velocities of the housing and fin was the best match to CFD data.