http://yetl.yabesh.ir/yetl1/handle/yetl/19033 2026-09-02T08:06:21Z 2026-09-02T08:06:21Z Ahmed, Rizwan Ferhatoglu, Erhan Tamatam, Lakshminarayana Reddy Firrone, Christian Maria Zucca, Stefano http://yetl.yabesh.ir/yetl1/handle/yetl/4316948 2026-08-23T08:43:24Z 2026-01-01T00:00:00Z

An Improved Experimental Validation of Nonlinear Forced Response Simulation of Shrouded Blades Ahmed, Rizwan; Ferhatoglu, Erhan; Tamatam, Lakshminarayana Reddy; Firrone, Christian Maria; Zucca, Stefano Abstract. Friction damping devices like tip shrouds are usually employed in low pressure turbine (LPT) blades to reduce their large vibration amplitudes. From an engineering point of view, experimental validation of the numerically predicted dynamic behavior of the blade is essential to demonstrate the damping performance of shrouds in LPTs. In accordance with this purpose, this study presents the comparison of experimental and numerical results for the detailed investigation of the dynamic behavior of shrouded turbine blades. A brief overview of the experimental test rig, which has been previously developed to measure both the nonlinear forced response and contact forces simultaneously, is first presented. The experimental results show the effect of different normal preloads and excitation force levels on the measured parameters. To compute the nonlinear forced response of the blade and the shroud contact forces, the test rig is modeled in a commercial finite element (FE) software, and the system matrices are extracted in a reduced order form. The harmonic balance method (HBM) is applied in a nonlinear solver developed dedicatedly with the implementation of a 3D contact model. The comparison of the experimental and numerical results is presented in particular cases where lower normal preload to excitation force ratio results in alternate stick and slip transitions. The results show that experimental dynamic behavior of shrouded blade is computationally captured in most of the cases. The nonmatching results are also highlighted for some cases in which the nonunique contact forces introduce the response variability. For these cases, response boundaries are numerically estimated by utilizing an optimization algorithm. The outcomes of this paper consequently exhibit a detailed validation procedure for the simulation tools and an understanding of the numerical concerns like convergence.

2026-01-01T00:00:00Z Scott-Emuakpor, Onome Johnson, Philip Vadrevu, Harshith Ulsenheimer, Artur Stewart, Calvin http://yetl.yabesh.ir/yetl1/handle/yetl/4316944 2026-08-23T08:43:16Z 2026-01-01T00:00:00Z

A Novel Accelerated Fatigue Testing Method for Rapid Additive Manufacturing Qualification Scott-Emuakpor, Onome; Johnson, Philip; Vadrevu, Harshith; Ulsenheimer, Artur; Stewart, Calvin Abstract. This work presents a new accelerated fatigue testing method by comparing the experimental results to standard axial fatigue data from a standard database. Motivation for the accelerated testing method comes from advancements in additive manufacturing (AM) processes that enable the development of new materials for future weight and fuel savings in gas turbine engines. To realize these benefits for gas turbine engines sooner, the complexity of AM process parameters needs to be understood and qualified in a rapid fashion, and fatigue uncertainty needs to be proven. The comparison of the accelerated fatigue testing method and standard axial fatigue testing for aluminum 6061-T6 resulted in three key findings. First, an optical strain calculation method that promotes reduced test setup time is validated. Second, the fatigue life results are statistically comparable and within a 99% prediction interval band of each other. Finally, accelerated fatigue required only 5 h of testing time to generate the data in this work versus 100 days for the axial fatigue data. This means that the accelerated fatigue testing method characterized fatigue life of aluminum approximately 500 times faster than the standard test.

2026-01-01T00:00:00Z Lanjewar, Saurabh Kumar, Pramod Gopi, Pramod Chandra http://yetl.yabesh.ir/yetl1/handle/yetl/4316940 2026-08-23T08:43:07Z 2026-01-01T00:00:00Z

Analytical Model for Leakage Prediction in an Axial Labyrinth Seal Lanjewar, Saurabh; Kumar, Pramod; Gopi, Pramod Chandra Abstract. Compact size and efficiency of a radial turbomachine make it a preferred choice for submegawatt (MW) scale supercritical CO2 (sCO2) power plants. At submegawatt power thresholds, mitigation of parasitic losses stemming from working fluid leakage at the rear facet of turbomachinery emerges as a critical issue. Consequently, it is essential to precisely quantify the leakage rates during the preliminary design of turbomachinery. This paper introduces a novel, one-dimensional leakage prediction model targeted at a see-through sCO2 labyrinth seal configuration. The proposed model is underpinned by a theoretical framework and corroborated through experimental findings from literature and computational simulations. Parametric examinations of the see-through sCO2 labyrinth seal, spanning diverse geometrical configurations and operational conditions are numerically investigated. A dimensionless leakage function is suggested to outline the operational characteristics typical of a sCO2 labyrinth seal. The model demonstrates high accuracy in predicting leakage rates across all examined conditions, with an error margin of within ±10%. This analytical tool exhibits expedited computation capabilities while adeptly ascertaining leakage rate, static pressure distribution within the seal cavities, and temperature drops at individual seal teeth. The utility of this leakage prediction model not only extends to preliminary labyrinth seal designs but also facilitates rotor dynamic analysis to be comprehensively investigated.

2026-01-01T00:00:00Z Shamsi, Syed Safeer Mehdi Barberis, Stefano Lancini, Cesare Maffulli, Gianfranco Biliotti, Davide Traverso, Alberto http://yetl.yabesh.ir/yetl1/handle/yetl/4316935 2026-08-23T08:42:59Z 2026-01-01T00:00:00Z

Multicriteria Optimization and Comparison of ACAES and PTES for Long Duration Energy Storage Market Shamsi, Syed Safeer Mehdi; Barberis, Stefano; Lancini, Cesare; Maffulli, Gianfranco; Biliotti, Davide; Traverso, Alberto Abstract. With the penetration of renewable energy sources into the market, energy arbitrage, i.e., to store energy from the grid at the time of low demand (thus at lower or negative cost) and release it into the grid at the time of high demand (at higher cost), is becoming common practice. To better harness the price curves in expanding renewable energy markets, large scale energy storage solutions with GWh of storage capacities, hundreds of MWs with flexible charging and discharging rates are required; utility scale storages should feature approximate charging time of 6 h–10 h, shaving peak renewable energy production load from the grid in the daytime and 10+ h discharging time at the night to meet the consumer electricity demands. Adiabatic compressed air energy storage (ACAES) is an high-efficient thermomechanical energy storage solution able to provide such large scale arbitrage services, which is currently close to commercialization thanks to the work of startups and companies around the world and that is laying its capabilities on already demonstrated potential by compressed air energy storage systems in terms of high lifetime scalability, low self-discharge, long discharge times, relatively low capital costs, and high durability. On the other hand, pumped thermal energy storage (PTES), although still at a more infant technological development level, aims for the same category of storage solutions while providing additional benefits of no geographical constraints and no pressurized storage equipment in contrast to ACAES. This study compares the more technologically ready ACAES technology with emerging PTES technology for multiple technoeconomic criteria with industrial constraints on commercially available turbomachinery. Both ACAES and PTES are modeled for providing 100 MW of discharging power for 12 h with 6 h of charging targeting a round-trip efficiency of 70%. These constraints are then used to optimize the thermodynamic operating parameters of both technologies for analyzing the specific cost of charging, storage and discharging equipment and performance parameters in terms of energy density and levelized cost of electricity (LCOS). The study shows that when compared to basic and advanced configurations, PTES shows lower LCOS than ACAES while the energy density is comparable. However, if looked at the specific cost of charging and discharging, ACAES is currently cheaper than PTES for both configurations. However, that may change with the presence of hot temperature compressors, which may eliminate the need for an electric heater to reach the required operating temperature in PTES.

2026-01-01T00:00:00Z