bluuebunny/crossref_metadata_2025_split huggingface dataset:
The Influence of Turbulence and Reynolds Number on Endwall Heat Transfer in a Vane Cascade
Authors: Yel Mahi Maliha , Chukwuemeka Emmanuel , Donovan Shaun , Ames Forrest , Kanani Yousef , Acharya Sumanta 
Published: October 2022

Abstract
Endwall heat transfer measurements have been acquired in a vane cascade over a range of turbulence conditions and Reynolds numbers using an array of small commercial infrared (IR) cameras. The linear cascade was tested over five inlet turbulence conditions ranging from low turbulence (0.7%) to high turbulence (17.4%) and three exit chord Reynolds numbers ranging from 500,000 to 2,000,000. The small commercial IR cameras made by Therm-App have a resolution of 384 by 288 pixels and were connected to individual smart phones to record the images. The cascade was modified with small zinc selenide windows to provide IR access for the cameras. The five cameras were calibrated against a constant temperature test plate and the output images were adjusted for the fisheye effect and thermal droop at the edges. The large-scale low-speed cascade, used in the endwall heat transfer study, was configured in a four vane three full passage arrangement. The vane design includes a large leading and aft loading. This same cascade has been used in the acquisition of vane surface heat transfer distributions, vane suction surface heat transfer visualizations, and vane surface film cooling distributions. This paper includes comparisons with two LES calculations, which were conducted prior to the acquisition of the heat transfer data. The influence of the secondary flows on the endwall heat transfer distributions, including the leading edge horseshoe vortex system, is particularly visible at lower turbulence levels and lower Reynolds numbers. However, at higher turbulence levels the influence of secondary flows is less visible but the influence of Reynolds number and turbulence on transition can be discerned.
Leakage and Rotordynamic Performance of a Hole-Pattern Multiphase Pump Seal
Authors: Zhang Min , Childs Dara W. 
Published: October 2022

Abstract
Understanding the leakage and rotordynamic performance of a hole-pattern annular seal is critical to the design of a centrifugal pump regarding vibration characteristics and stability. The growing interest in 2-phase pumping, handling gas components in the oil stream directly, brings more challenges to pump design. This paper studies the leakage and rotordynamic performance of a hole-patten annular seal under bubbly (oil/air) flow conditions. The test seal’s length-to-diameter ratio is 0.75. The rotor surface is smooth, and the seal inner surface is textured (65% of the area is occupied by round holes with a depth of 2.5 mm). The test fluid is comprised of silicone oil and air, and the gas volume fraction GVF at the seal inlet is from zero to 9.3%. Tests also cover two pressure drops (44.8 and 55.1 bars) and three rotor speeds (5, 10, and 15 krpm). Test results showed that adding air to the oil (inlet GVF up to 9.3%) has a small impact on mass flow leakage. Mass flow leakage increases slightly (by ∼4%) as inlet GVF increases from zero to 3.4% and then decreases slightly (by &lt; 5%) as inlet GVF is further increased to 9.3%. As inlet GVF increases, measured values of direct stiffness K, direct damping C, cross-coupled damping c, and direct virtual-mass M decrease. Adding air to the oil (inlet GVF up to 9.3%) shows no obvious impact on measured cross-coupled stiffness k and measured effective damping Ceff. Measurements are also used to examine San Andres’s bulk-flow model (2011, “Rotordynamic Force Coefficients of Bubbly Mixture Annular Pressure Seals,” ASME J. Eng. Gas Turbines Power, 134(2), p. 022503). The model shows limited capability in predicting the performance of the hole-pattern seal under mainly-oil conditions. The discrepancy between the experimental results and theoretical predictions calls for more improvements in the predictive model to handle hole-pattern seals with mainly-oil mixtures.
Reconstructing Turbine Non-Uniform Flow Including Hot Streaks Using Spatially Under-Sampled Measurements
Authors: Zhu Xu , Lou Fangyuan , Zhou Kai , Zheng Xinqian 
Published: October 2022

Abstract
The demand for higher thermal efficiency of gas turbines has been pushing the limit of turbine inlet temperature. Modern high-pressure turbine (HPT) blades are cooled with a combination of film cooling, impingement cooling, and passage cooling. However, for a given material and cooling strategy, the turbine inlet temperatures are limited by the performance penalty caused by the required cooling air typically extracted from the high-pressure compressor. Although it is well recognized that the HPT inflow is highly unsteady and non-uniform, it is still generally the case that turbines are designed for uniform inlet temperature — often the predicted peak gas temperature due to the vacancy of a reliable methodology for estimating the non-uniform temperature field at HPT inlet. This paper introduces a new approach to predicting the turbine inlet temperature, including the magnitude of non-uniformity, based on a few temperature measurements at the HPT exit to shed light on this topic. The technique includes three steps. First, investigate the hot streaks migration across the HPT and establish a projection of hot-streaks-related magnitude from HPT inlet to exit. Second, resolve the hot-streaks-related extent at HPT exit using a multi-wavelet approximation method based on a few discrete measurements. Lastly, estimate the HPT inlet mean temperature and magnitude of hot streaks. The method’s effectiveness is examined using the two-stage high-pressure turbine from Energy Efficiency Engine (E3). An engine representative HPT inlet temperature distribution available in the open literature is applied at the HPT inlet. The true temperature distribution at HPT exit is obtained from full-annulus unsteady simulations. The estimated HPT inlet temperature distribution using the new approach agrees with the true values, with an error of less than 0.3% in the mean temperature and uncertainty on the order of 20% in the magnitude of hot streaks.
Roller Bearing Skidding for Aero-Engine Applications: All-Steel Versus Hybrid Bearings
Authors: Dadouche Azzedine , Kerrouche Rami 
Published: October 2022

Abstract
Roller bearings operating under light loads may suffer from skidding. The latter is more pronounced as the speed increases and may result in extensive wear and reduced service life of the bearing. The main objective of this study is to analyze skidding occurrence in a custom-made all-steel M50 bearing and a hybrid roller bearing subjected to the same operating conditions. The test bearings have a bore diameter of 90 mm, an outer diameter of 125 mm and 26 rollers. The hybrid bearing features silicon nitride (Si3N4) rollers and steel rings (M50 outer ring and M50-NIL inner ring). The bearings feature special channels to allow for under race lubrication of the bearing components in relative motion. A suite of sensors were used and installed to detect skidding and monitor the overall performance of the test bearing such as vibrations and temperature. The effect of the radial applied load, shaft rotational speed and oil flow rate on roller skidding have been investigated and discussed. Slip ratio for each of the bearings under various speed-load combinations was also determined and analyzed. Turbo oil 2380 was used to lubricate the test bearings at a constant temperature of 77°C. Tests were conducted on a high-speed rolling bearing test rig and data was recorded using a 24-bit data acquisition system.
Nonlinear Surrogate Models for Gas Turbine Diagnosis
Authors: Loboda Igor , González Castillo Iván , Yepifanov Sergiy , Zelenskyi Roman 
Published: October 2022

Abstract
In gas turbine diagnostics, a significant contradiction is observed between the variety of methods proposed and a limited number of the algorithms realized in real monitoring systems. One of the explanations is the shortage of simple, but reliable and accurate diagnostic solutions. Many actual solutions are based on a nonlinear thermodynamic model; however, this physics-based model and an iterative procedure to adapt it are complex, critical to computer resources, and does not always converge. On the other hand, the used linear models are simple, but not accurate enough.
The present paper proposes and analyzes two types of nonlinear simplified static data-driven models based on the steady-state data generated by the thermodynamic model. The first type includes direct models that compute monitored variables Y for given operating conditions U and fault parameters δΘ. The second type presents inverse models that estimate parameters δΘ using variables U and Y as inputs. The paper aims to create such models, optimize them, and show that they can be a good surrogate for the original thermodynamic model and its adaption procedure.
Based on the experience of the development of baseline models, we employ polynomials and multilayer perceptron as approximation techniques. Adjustment of the techniques and their comparison allow choosing the best one. To draw solid conclusions on the utility of the proposed models, three different engines are used as test cases. The results of the verification of these models are promising for their use in gas turbine diagnostic and control systems.
A Review of Pressure Gain Combustion Solutions for Aerospace Propulsion
Authors: Purushothaman Sreenath , Renuke Avinash , Sorce Alessandro , Traverso Alberto 
Published: October 2022

Abstract
Recent developments in Pressure Gain Combustion (PGC) technology have demonstrated its ability to achieve higher thermal efficiencies and lower carbon emissions as compared to conventional gas turbine counterpart working in Brayton cycle. Ongoing studies suggest the possibility of implementing PGC in aircraft engines by replacing the high-pressure section (HP compressor, combustion chamber and HP turbine) with a PGC system. This, coupled with research on advanced materials and cooling solutions, offers the potential for higher overall gas turbine efficiency and fuel economy, contributing towards emission reduction of the aviation sector.
This paper aims at a comprehensive review of PGC technology solutions applied in the area of aero propulsion. Reported background covers the historic as well as ongoing research activities at the component level, the cycle level, and the propulsion application of Pulse Detonation Engine (PDE), Rotating Detonation Engine (RDE), Oblique Detonation Wave Engine (ODWE), Free Piston Composite Cycle Engine (FP-CCE), and wave rotor engines. The analytical, numerical, and experimental research work is reviewed, providing also a comparison of PGC engine conceptual designs with existing gas turbine engines used in aerospace propulsion.
Numerical Investigation of Laidback Fan-Shaped Film Cooling Holes With Large Eddy Simulation
Authors: Yang Lianfeng , Satta Francesca , Barsi Dario , Zunino Pietro , Luan Yigang 
Published: October 2022

Abstract
Due to the high demand for the output power and thermal efficiency, the turbine inlet temperature is extremely high which has significantly exceeded the melting point of the blade material. Therefore, the turbine blade cooling system plays a pivotal role in the entire engine. As for the external cooling, film cooling technology has been widely used in the modern advanced design of gas turbines in order to enhance the cooling performance and reducing the cooling air usage. According to the public literature, conventional cylindrical film cooling hole has been studied by many researchers, whereas the laidback fan-shaped film cooling hole, as a cutting-edge technology, is relative novel, advantageous and still under investigation. Thus, large eddy simulation (LES) method was implemented to study the flow field and the thermal performance of shaped film holes at turbulence intensity Tu = 0.5%, density ratio DR = 1.5, blowing ratio M = 0.5–3.0 and momentum flux ratio I = 0.17–6.00. The adiabatic film cooling effectiveness with LES shows a good agreement with the experimental data. A comparison was conducted between the conventional cylindrical film hole and the laidback fan-shaped film hole in the range of M = 0.5–1.5. The results show that shaped film hole obtains better cooling effectiveness with sufficient spread in spanwise direction as the blowing ratio increases, and M = 1.5 can provide a relative better performance for shaped film hole. As for the details of the flow field, the counter-rotating vortex pair (CRVP) and anti-CRVP structures are found in the simulation. Time-averaged Reynolds shear stresses and turbulence viscosity exhibit strong anisotropic properties near the bottom surface. The analyses may help to understand the characteristics of the laidback fan-shaped film cooling and guide the cooling design of the turbine blade.
Predicting Cavitation Erosion on Two-Stage Pumps Using CFD
Authors: Verhulst Tedja , Ng Eddie Yin-Kwee , Chung Yongmann , Judt David , Lawson Craig 
Published: October 2022

Abstract
Cavitation is a common problem that occurs in pumps which reduces its useful life and bring increased operating costs to the user. A study of cavitation erosion on a two-stage centrifugal pump has been carried out using Computational Fluid Dynamics (CFD). Most cavitation studies on pumps have been focused on modelling the severity of cavitation; specifically, on understanding its visual effects and performance penalties. Few works have been carried out to predict the most erosion-sensitive areas inside a pump. The focus of this study is on modelling the permanent damage that would be caused by cavitation and to identify specific areas within the pump which are most susceptible to erosion. The model is first validated against experimental data from another work. Once the simulation has been successfully calibrated, the cavitation simulation is carried out again with the subject pump. Not only does this work extend the findings previous works by predicting cavitation erosion on a two-stage pump, but the pump rotation speed is also varied to observe how the erosion-sensitive areas on the pump changes as a result. A specific focus on the Gray Level Method is carried out to predict the erosion damage on the pump. This technique is chosen as it has been experimentally proven with single-stage radial pumps, using specialized CFD code. It is found that the algorithm used to predict erosion when applied with commercial CFD packages, are useful in distinguishing areas inside the pump which are most vulnerable to erosion damage. The Scherr-Sauer cavitation model coupled with the κ-ω SST turbulence model have been used to run the cavitation simulations.
Experimental Investigation of Heat Transfer in a Rotating Lateral Outflow Trapezoidal Channel With Pin-Fins
Authors: Zhang Xuejiao , Li Haiwang , You Ruquan , Liu Song , Tao Zhi 
Published: October 2022

Abstract
In this study, the heat transfer characteristics in a rotating lateral outflow trapezoidal channel with pin-fins, which is a typical model of the internal cooling passage in a turbine blade, were experimentally investigated under the Reynolds number range of 10,000–80,000, rotating speed range of 0–1000 rpm. The tested Re and Ro ranges are considerably extended from the previous experiences. For the non-rotating condition, the heat transfer characteristics of the leading and trailing sides of the internal channel are relatively uniform due to the different construction. On the inner smooth surface, at Re = 30000 of non-rotating, the leading and trailing averaged Nusselt number of the point near the inlet is about 48% higher than that at the end of the channel, but on the outer pin-fin arrayed surface, the averaged Nusselt number decreases about 20.5%. For the rotating conditions, the heat transfer of inner leading surface significantly reduced due to the rotation-induced Coriolis force and coolant discharged from the channel along the outlets. Interestingly, with Reynolds number increases, the Nusselt number ratios decreases. When the rotating speed is 1000 rpm and the Reynolds number is 10000, 3000, 50000 and 70000, the Nusselt number ratios are 2.11, 1.40, 1.19 and 1.07 respectively. Moreover, the leading side of the inner smooth area exhibit a critical rotation number, in which the rotation weakened the heat transfer before the critical point and promoted heat transfer after the critical point. However, the critical rotation number varied with X/D.
Centrifugal Compressor Retrofit: Geometry Rebuild and 3-D Blade Shape Optimization
Authors: Kienzle Norman , Hoang Duc Huy Marco , Martis Warren John , Moch Markus , Doetsch Christian , di Mare Francesca 
Published: October 2022

Abstract
This article summarizes the development of an aerodynamic retrofit for a centrifugal compressor stage. In the first part, a method to replicate the open design case ‘Radiver’ (RWTH Aachen University), using an in-house tool (NarTIG) is presented. The geometry is then used as a starting point for a 3D aerodynamic full stage blade shape optimization. The results of the optimization are shown in the second part of the paper. The results of the fully 3D-optimized profiles of the impeller blades and diffuser vanes show a significant reduction of spanwise leading edge loading, leading to an increase of 2-percentage points in total-static polytropic efficiency at optimal conditions. An increase of 20-percentage point with respect to high flow conditions is also reached.
A Machine Learning Approach for Stress-Rupture Prediction of High Temperature Austenitic Stainless Steels
Authors: Hossain Md Abir , Mireles Adan J. , Stewart Calvin M. 
Published: October 2022

Abstract
This study outlines a machine learning approach for long-term stress-rupture (SR) prediction of high temperature austenitic stainless steel. Traditional methods of lifetime estimation and alloy design for turbomachinery application rely mostly on repeated testing, prior experience, and trial-and-error approach, which are laborious, time intensive, and costly. Recent advances in machine learning offer an accelerated technique for the development of constitutive creep laws, superior alloy designs, and reliable long-term performance prediction. To that end, a machine learning approach is explored in this study for long-term stress-rupture prediction. The toolbox GPTIPS, a biologically inspired genetic programming (GP) algorithm for building accurate and intrinsically explainable non-linear regression model is employed in this study. In GPTIPS, randomly sampled tree structures, mutate and cross over the best performing trees to create a new sample. The process iterates until the best solution is found based on criteria set by the user. Herein, the stress-rupture data of 18Cr-8Ni (304 SS) stainless steel, divided into 60% training and 40% testing data irrespective of heat grades are feed into GPTIPS. The GPTIPS is iterated based on the number of genes, tournament size, tree depth, and nodes. The generated SR constitutive models are ranked according to goodness-of-fit and model complexity. The best-ranked models are compared with the experimental data and found to be free of inflection points at low-stress. Post audit validation is performed by fitting the model blindly against an extended data base of 18Cr-12Ni-Mo (316 SS) stainless steel. Based on the goodness-of-fit, the best-ranked models are investigated for future application, comprehensive understanding of their limitations, and the resultant capability of effective prediction. In future work, the ability of GPTIPS will be leveraged to develop minimum-creep-strain-rate models, alloy design based on chemical composition, potential sources of uncertainty, and their implications on the outcomes.
Optimization of the parameters impacting the Direct Red 89 degradation with thermally activated persulfate using a full factorial design
Authors: Nadji Nawel , Bouarra Nabil , Nouri Loubna , Djebli Abdelkrim , Boudjemaa Amel , Nouri Nabila , Hemidouche Sabra , Djerad Souad , Bachari Khaldoun 
Published: October 2022

A two-level full factorial design with interactions was effectively used to screen for parameters impacting the degradation of Direct Red 89 (DR89) by thermally activated persulfate. Four variables were identified as critical: reaction temperature, persulfate concentration, initial pH of medium, and initial DR89 concentration. The goodness of fit of the reduced model was tested by generating plots of descriptive statistic, residuals versus predicted responses, normal probability versus residuals, and observed versus predicted values, as well as examining the analysis of variance table. The observed and the predicted response values of the reduced model exhibited a good correlation, with R2, [Formula: see text] , Q2, and p of 0.990, 0.983, 0.968, and 0.000, respectively. To determine optimal operating parameters, the desirability function was utilized, and it was determined to be 0.988 with a predicted response of 99.89% for an initial DR89 concentration of 51.96 mg/L, a persulfate concentration of 12 mmol/L, a reaction temperature of 60 °C, and a pH of 3.
Autologous Platelet-Rich Plasma Improves Pregnancy Outcomes of Patients with Thin Endometrium Regardless Endometrial Thickening: Multicenter Retrospective Study with Elimination of Embryonic Confounders
Authors: Suzuki Satoshi , Kusumi Maki , Maeda Tomoko , Kawai Kiyotaka , Kawamura Toshihiro , Okamoto Eri , Jo Toushun , Tsutsumi Ryo , Takamizawa Satoru , Nakayama Takahiro , Nabeta Motowo , Nishiyama Yukio , Nomiyama Mari , Furui Kenji , Morimoto Yoshiharu , Tsutsumi Osamu 
Published: October 2022

Objective: To determine whether endometrial thickening is an important factor for pregnancy outcomes in platelet-rich plasma (PRP) treatment for patients with thin endometrium. Methods: Data from the registry database of the Japan Gynecologic PRP Study Group from April 2019 to October 2021 were analyzed retrospectively. A total of 208 patients who underwent single blastocyst transfer (SBT) after PRP due to thin endometrium (¡8 mm) in their previous cycle were included in the study. Their pregnancy outcomes were compared with their own historical data before PRP infusion. The same patient group was then divided into 136 patients whose endometrium thickened after PRP and 72 patients whose endometrium did not, and the pregnancy outcomes of the two groups were compared. Furthermore, to eliminate embryonic confounding, 28 patients who had single euploid blastocyst transfer (SEBT) with preimplantation genetic testing for aneuploidy (PGT-A) were selected from the same patient group and divided into two groups of 22 patients whose endometrium thickened and 6 patients whose endometrium did not, and the pregnancy outcomes were compared in the same method. Results: After PRP administration, the clinical pregnancy rate, live birth rate, and miscarriage rate were all significantly improved compared with the historical controls (34.1 vs 20.0, [Formula: see text]; 22.6 vs 3.9, [Formula: see text]; 33.8 vs 73.4, [Formula: see text]). There were no statistically significant differences in the respective rates between the “thickened endometrium” group and the “unthickened endometrium” group in SBT group (36.0 vs [Formula: see text], [Formula: see text]; 25.7 vs [Formula: see text], [Formula: see text]; 28.5 vs [Formula: see text], [Formula: see text], respectively). Likewise, in the SEBT with PGT-A group, there were no statistically significant differences in results between the two groups (36.4 vs [Formula: see text], [Formula: see text]; 36.4 vs [Formula: see text], [Formula: see text]; 0 vs [Formula: see text], respectively). Conclusions: PRP administration to patients with thin endometrium improves pregnancy outcomes even when endometrial thickening is not achieved.