首页期刊导航|Journal of engineering for gas turbines and power: Transactions of the ASME
期刊信息/Journal information
Journal of engineering for gas turbines and power: Transactions of the ASME
American Society of Mechanical Engineers
American Society of Mechanical Engineers
季刊
0742-4795
Journal of engineering for gas turbines and power: Transactions of the ASME/Journal Journal of engineering for gas turbines and power: Transactions of the ASMEEI
Sang-Guk KangJe Ir RyuAusten H. MotilyPrapassorn Numkiatsakul...
121001.1-121001.11页
查看更多>>摘要：Energy addition using a hot surface ignition device is required for reliable ignition of aircraft compression ignition engines running on fuel variations and at altitude conditions. Thus, durability of the hot surface ignition device is crucial for application in these engines. Thermomechanical stress is one of the key parameters that determine durability, which requires an accurate prediction of the transient temperature field based on well-defined boundary conditions representing the dynamic and complex fluid flow inside engines. To meet this requirement, the present study focuses on transient thermomechanical stress analysis using a sequentially coupled computational fluid dynamics (CFD)-finite element analysis (FEA) approach to understand transient thermomechanical responses of the hot surface ignition device. A three-dimensional transient reacting flow simulation was conducted first using CONVERGE software, the results of which were exported to map thermal and pressure boundary conditions onto a structural finite element mesh. Transient thermomechanical stress analysis was performed sequentially using ABAQUS software utilizing the mapped boundary conditions. The results such as transient temperature history, resultant thermomechanical stress, displacement, potential failure modes, etc., were critically reviewed, which can provide helpful information for further design improvement.
Francesco BalduzziIacopo CatalaniNicola PiniLuigi Mosciaro...
121002.1-121002.11页
查看更多>>摘要：The accurate evaluation of thermally-induced stresses is of particular importance for life-cycle analysis of modern turbochargers. Conjugated heat transfer (CHT), steady-state calculations represent the state-of-the-art, whose temperature distribution is usually imported into a structural solver as a thermal load for carrying out thermo-structural analyses. In the case of transient analyses, however, issues arise. Indeed, due to the different timescales of convective and conductive heat-transfer mechanisms, unsteady CHT simulations are burdened by high computational costs. Moreover, in the specific case of turbocharged engines, the timescales of engine load transients and turbocharger response may differ by a factor of up to 10~5. The present study proposes an approach for carrying out transient thermo-structural analyses of the solid domain only, characterized by a physical time in the order of 10~1 s, without the need for unsteady fluid flow calculations, which would imply the use of a solver time-step in the order of 10~(-5) s. In the proposed methodology, the effects of the fluid flow in the heat-transfer process are modeled by imposing adequate boundary conditions to wet surfaces of the solid domain with minimum computational effort. Indeed, by performing two steady-state CHT calculations and one steady-state computational fluid dynamics (CFD) calculation, time-dependent boundary conditions can be derived in terms of convective heat transfer coefficient and near-wall fluid temperature. The case study used for model development is a high-performance turbocharger turbine for automotive applications, responding to engine load transients of tenths of seconds. Initially, steady-state CFD and CHT models of the turbine stage are validated against experimental data. Then, transient analyses on the turbine wheel are carried out, and their results are imported as thermal loads into an unsteady structural solver, allowing for accurate transient thermo-structural analyses at sustainable computational cost.
查看更多>>摘要：This study is a continuation of previous work aimed at elucidating the effect of hydrogen-cofiring and exhaust gas recirculation (EGR) on combined cycle (CC) performance. The thermodynamic analysis was expanded to include postcombustion capture (PCC) by means of mono-ethanolamine (MEA). Attention was paid to net power output and thermal efficiency. Part-load operation of the CC without carbon capture was taken as a reference. Decarbonization solutions, in ascending order of complexity, included the following: (1) adding a PCC unit; (2) combining EGR with PCC, so as to exploit the increase in the flue gas CO_2 concentration while reducing the exhaust gas flow delivered to the absorber; (3) including hydrogen cofiring at the largest capability dictated by the gas turbine (GT) combustion system, with the opportunity to explore a wider range of EGR rates, while still relying on PCC of the residual CO_2 in flue gas, before discharge into the environment. Scenarios were first discussed under the same GT load for consistency with the published literature, thus enabling the validation of the modeling procedure. Then, CC net power production was assumed as the basis of comparison. The third solution was found to be the most promising thus minimizing both the energy penalty due to carbon capture and CO_2 emission intensity (EI).
Mertol TuefekciFadi El HaddadLoiec SallesRichard Setchfield...
121004.1-121004.11页
查看更多>>摘要：Complicated systems made of multiple components are known to be difficult to model, considering their solutions can change dramatically even with the slightest variations in conditions. Aircraft engines contain such complicated systems, and some components in aircraft engines' turbines can cause significant changes in the system's overall response. Hence, this study is focused on investigating the behavior of a turbine blade of an aircraft engine and the effects of the contact between the blade and the seal wire on the dynamics of the blade-disk system. The investigation is performed via various numerical simulations in time andfrequency domains. One sector of the bladed disk is modeled using the finite element method with the lock plate and the seal wire imposing cyclic symmetry boundary conditions in the static, modal, and frequency domain forced response analyses. In time domain analyses, the cyclic symmetry is replaced with simplified displacement restricting boundary conditions. The time domain analysis contains steady-state forced responses of the system. The results show that contact with the seal wire is not a major source of nonlinearity and damping. The contacts with the lock plate contribute more to the vibration damping than the seal wire. However, compared to the contacts at the root of the blade, both components remain less significant with regard to frictional damping and nonlinearity.
查看更多>>摘要：This study is based on time-series data taken from the combined cycle heavy-duty utility gas turbines. For analysis, first a multistage vector autoregressive model is constructed for the nominal operation of the powerplant assuming sparsity in the association among variables and this is used as a basis for anomaly detection and prediction. This prediction is compared with the time-series data of the plant-operation containing anomalies. The comparative advantage based on prediction accuracy and applicability of the algorithms is discussed for the postprocessing. Next, the long-memory behavior of residuals is modeled, and heterogeneous variances are observed from the residuals of the generalized additive model. Autoregressive fractionally integrated moving average (ARFIMA) and generalized autoregressive conditional heteroskedasticity (GARCH) models are employed to fit the residual process, which significantly improve the prediction. Rolling one-step-ahead forecast is studied. Numerical experiments of abrupt changes and trend in the blade-path temperature are performed to evaluate the specificity and sensitivity of the prediction. The prediction is sensitive given reasonable signal-to-noise ratio and has lower false positive rate. The control chart is able to detect the simulated abrupt jump quickly.
Sean P. CooperDamien NativelOlivier MathieuMustapha Fikri...
121006.1-121006.8页
查看更多>>摘要：Syngas is a desirable fuel for combustion in the Allam-Fetvedt cycle, which involves combustion under supercritical-CO_2 conditions. While some work has been conducted in collecting ignition delay times (IDT) at the extreme pressures required by these systems, significant model deficiencies remain. Additionally, considerable barriers in terms of nonideal gas dynamic effects have been shown for these experiments in shock tubes. Further investigation into the fundamental combustion kinetics of H_2/CO/CO_2 mixtures is required. Time-resolved speciation measurements for target species have been shown to better aid in improving the understanding of underlying chemical kinetics than global ignition delay time measurements. Therefore, laser absorption measurements of CO were measured behind reflected shock waves during combustion of syngas at 5 and 10 bar and temperatures between 1080 and 2100 K. The mixtures investigated utilized H_2-to-CO ratios of 1 :1 and 1:4, respectively, each at stoichiometric conditions, allowing for discussions of the effect of initial fuel composition. A ratio of fuel to CO_2 of 1:2 was also utilized to represent commercially available syngas. The mixtures were diluted in helium and argon (20% He, 76.5% Ar) to minimize thermal effects and to expedite CO thermal relaxation during the experiment. The resulting CO time histories were then compared to modern chemical kinetics mechanisms, and disagreement is seen for this system, which is assumed to be fairly well known. This study elucidates particular chemistry that needs improvement in moving toward a better understanding of syngas combustion at elevated pressures.
查看更多>>摘要：In the new era of renewable energy, flexible operation of conventional power plants is inevitable, causing high creep-fatigue life consumption. Conventional life assessment methods are deemed to be conservative to address the current requirements. The use of unified constitutive models for the analysis of damage evolution in steam turbine rotors in the past decade has shown promising results and is closely related to experimental data. However, identification of large number of material constants and high computational time hinder the widespread use of such models. In this paper, the latter is addressed using a novel representative input cycle (RIC) concept together with the noniterative asymptotic numerical method (ANM). Various startup shutdown sequences of a typical steam turbine rotor are studied using a unified constitutive model based on Chaboche's kinematic hardening including the damage parameter, Chaboche-Rousselier' s isotropic hardening model including the damage parameter, Norton's viscoplastic flow model, Lemaitre' s damage potential function and Kachanov-Rabotnov' s creep damage law. First, a conventional finite element method (FEM) technique is used and then the proposed RIC method is used to study the evolution of inelastic variables. The reduction in computational time and the compromise in accuracy using the proposed method are studied.
Silvia TrevisanSyed Safeer Mehdi ShamsiSimone MaccariniStefano Barberis...
121008.1-121008.9页
查看更多>>摘要：The industrial sector is a major source of wealth, producing about one-quarter of the global gross product. However, industry is also a major emitter of CO_2 and it represents a key challenge toward achieving the worldwide CO_2 emission reduction targets. Nowadays, about 22% of the overall energy demand is heating for the industrial sector, generating about 40% of the global CO_2 emissions. Additionally, 30% of the final energy demand of the industrial sector is electricity. Solutions to decarbonize the industrial sector are needed. This work presents the techno-economic assessment of four different molten salts-based power-to-heat-to-heat and power solutions aiming at decarbonizing the industrial sector, requiring medium temperature heat. The systems are studied under different electric markets. Dispatch strategies and system sizing are identified to ensure optimal techno-economic performance. The main performance indicators investigated are the levelized cost of heat and electricity (LCoH and LCoE), the operational expenditure, and the attainable savings with respect to alternative business as usual solutions. The results highlight that the proposed system can be cost-competitive, particularly in markets characterized by low electricity prices and high daily price fluctuations, such as Finland. In these locations, LCoE as low as 100 €/MWh and LCoH lower than 55 €/MWh can be attained by the base system configuration. The introduction of high temperature heat pumps can provide further LCoH reduction of about 50%. This study sets the ground for further power-to-heat-to-heat and power techno-economic investigations addressing different industrial sectors and identifies main system design strategies.
查看更多>>摘要：Knowledge of flame responses to acoustic perturbations is of utmost importance to predict thermoacoustic instabilities in gas turbine combustors. However, measuring transfer functions linking acoustic quantities upstream and downstream of flames are very challenging in practical systems and these measurements can significantly deviate from state-of-the-art models. Moreover, there is a lack of studies investigating the effect of hydrogen enrichment on the response of natural gas (NG) flames. In this work, measurements of flame transfer matrices (FTMs) of turbulent H_2/NG flames in an atmospheric combustor featuring an axial swirler burner have been performed, allowing us to unravel the transition between FTM in fully premixed (FP) and in technically premixed (TP) conditions. Furthermore, imaging of OH* chemiluminescence and OH-planar laser induced fluorescence are obtained for characterizing the topology of the flame for varying H_2 fraction and mixing conditions. Transfer matrices are measured using the multi-microphone method for H_2 fractions ranging from 12% to 43% in power. Afterward, the flame transfer functions (FTFs), which linearly relate the coherent fluctuations of the heat release rate to the acoustic velocity oscillations, are obtained from the FTM by using the Rankine-Hugoniot jump conditions across the flame. Using the OH* chemiluminescence intensity as a surrogatefor the heat release rate, the FTF based on this optical measurement is also extracted and compared to the one exclusively obtained with the multimicrophone method. As expected, the two different methods are in very good agreement for the FP case and significantly differ for the TP case. Indeed, chemiluminescence fluctuations cannot be directly linked to heat release rate fluctuations when the acoustic forcing induces equivalence ratio fluctuations at the flame, making the optical method unusable for TP configurations. We also show that the two methods agree in the high end of the explored excitation frequency range and we provide an explanation to this intriguing finding. Moreover, we investigate the sensitivity of the FTM measurement to the estimate of the speed of sound in the rig in FP conditions. Finally, the measured FTFs are fitted with FTF models based on multiple distributed time delays. This allows us to explain the frequency dependence and the hydrogen fraction dependence of the gain and the phase in FP and TP conditions.
Alexander JaeschkeBernhard CosicDominik WassmerChristian Oliver Paschereit...
121010.1-121010.11页
查看更多>>摘要：Hydrogen as an essential part of future decarbonization of the energy industry makes it a crucial necessity to replace conventional, natural gas based concepts in gas turbine combustion. This paper presents an experimental study of a multi-tube jet flame burner. The study is carried out with natural gas and pure hydrogen fuel at gas turbine relevant conditions at atmospheric pressure. To identify key differences between hydrogen-air and natural gas-air flames on the overall robustness and flame flashback behavior, air bulk velocity (80-120 m/s), adiabatic flame temperature (1235-2089 K) and air inlet temperature (623-673 K) are varied over a wide range, covering a range of Reynolds numbers of 10,000-20,000. Depending on flame temperature, two different flame shapes are observed for natural gas-air flames. The shape of the hydrogen-air flame changes less over the range of flame temperatures tested, but is generally more compact. The process of fuel-air mixing is further investigated by concentration distribution measurements in a water tunnel setup. Therefore, planar laser-induced fluorescence is utilized for visualization. The measured concentration distributions confirm the overall good mixing quality but also give an explanation on the observed flashback behavior of the different burner designs at reacting tests. The findings of the study are composed in a flashback correlation combining the observed flashback drivers for the burner configurations investigated.
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