Assessment of the Comparability of Droplet Evaporation Fuel Sensitivities between a Unit Test Case and an Aviation Gas Turbine Combustor

Ruoff, Stephan; Rauch, Bastian; Clercq, Patrick Le; Aigner, Manfred

doi:10.2514/6.2019-0727

Cited by 4 publications

(3 citation statements)

References 17 publications

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“…As previously shown, the evaporation model is accurate for single-component fuels. Furthermore, the errors associated with use of Γ-functions that don't precisely match the measured compositions were found to be small in a previous study (Ruoff et al, 2019).…”

Section: Results Of Uncertainty Propagationmentioning

confidence: 67%

Numerical Simulation and Uncertainty Quantification of a Generic Droplet Evaporation Validation Test Case

et al. 2020

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Alternative jet fuels have a high potential to reduce emissions in aviation. A big difficulty for their introduction is the costly and lengthy assessment of fuel effects on combustion performance. In the present work, the evaporation of freefalling droplets of realistic size (D ≈ 80 µm) in a well-defined vertical laminar heated flow is studied experimentally and numerically. Measurements of droplet diameters and velocities using microscopic double-pulse shadowgraphy are conducted for several single species and systematically chosen conventional and alternative multi-component jet fuels.The results show that the experiment is fuel-sensitive with respect to evaporation. In this study, special attention is paid to unknown or uncertain boundary and initial conditions, which serve as input in the validation of the numerical models. Therefore, non-intrusive non-deterministic simulations using Polynomial Chaos Expansion are performed to account for these uncertainties. The uncertainty quantification displays that overall uncertainties are small enough to distinguish between the different fuels and to predict fuel-dependent effects on evaporation. Nevertheless, the uncertainties are not negligible. A sensitivity analysis shows a high sensitivity of the evaporation to the offset of the droplet from the centerline and to the uncertainty of the inflow gas temperature. Reducing the uncertainties of the two above-mentioned conditions is most promising in enhancing the validation experiment.

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Section: Results Of Uncertainty Propagationmentioning

confidence: 67%

Numerical Simulation and Uncertainty Quantification of a Generic Droplet Evaporation Validation Test Case

et al. 2020

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“…The main motivation of the current paper is to present and demonstrate this measurement concept to characterize the evaporation of fuel droplets and to discuss its performance. In the long term, this technique will be combined with LIF to investigate the evaporation of twoor three-component fuels and to provide validation data for numerical simulations of the evaporation of multicomponent aviation fuels [38]. This is part of a research program at DLR focused on the design of alternative fuels.…”

Section: Stefanie Werner and Wolfgang Meiermentioning

confidence: 99%

Measurement of evaporation of hydrocarbon droplets by laser absorption spectroscopy

Werner

Meier

2019

Appl. Phys. B

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Concentration measurements of evaporated hydrocarbon species by infrared laser absorption spectroscopy at a monodisperse droplet chain are presented. A droplet generator was installed within a ow channel and operated with cyclohexane, iso-octane, n-heptane, n-pentane and 1-butanol. The ow channel was ushed with a laminar ow of air at dierent temperatures. The absorption of a HeNe laser beam at λ = 3.39 µm traversing through the ow channel at varying distances from the droplet chain was exploited to determine the vapor concentrations of the hydrocarbons. Measurements of the absorption cross sections in a heated gas cell (T = 300 to 773 K) enabled the quantication of the absorption signals from the droplet chain. Vapor concentrations were determined in planes perpendicular to the droplet chain. From the increase of vapor concentration between the planes, the evaporation rate could be determined. The evaporation rates were measured in dependence of co-ow temperature, droplet velocity, droplet generation frequency and droplet spacing. In the investigated temperature range of the air (313-430 K) the evaporation rates increased linearly with temperature. The order of the fuels with respect to evaporation rates corresponded with the boiling points of the individual fuels. In addition to the presentation of the results, the paper discusses the performance of vapor concentration measurements by laser absorption spectroscopy at droplet chains which has not been tested before in such a conguration. Particular attention was paid to the spatial resolution of the measurement. The results are well suited to validate models and numerical simulations.

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“…In addition to the data collected, predictions from computer models enable the evaluation of SAF usage over the life cycle prior to the actual deployment in an aviation mission. These models cover, inter alia, the prediction of unknown fuel properties [9], the sensitivity of the combustion process on varying fuel composition in the engine [10] or the expected climate impact, e.g. from the resulting soot emissions.…”

Section: Introductionmentioning

confidence: 99%

A proposed Digital Twin concept for the smart utilization of Sustainable Aviation Fuels

Enderle

Rauch

Hall

et al. 2022

AIAA SCITECH 2022 Forum

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In the efforts to reduce both CO 2 emissions and non-CO 2 climate impacts in global aviation, encouraging the take-up of Sustainable Aviation Fuels (SAF) is seen as a key element. Although there are currently seven ASTM-approved SAF production pathways, availability of the required feedstock and increased costs compared to conventional jet fuels pose major challenges for a fast market uptake. It is therefore advisable to use the currently available capacities in a smart way, i.e. taking into consideration the maximum potential for mitigating climate impact for a given scenario as well as a cost-optimal and economic efficient allocation in the operational context. For such complex tasks, all information regarding the system under consideration should be made available over the entire lifecycle. For this purpose, a Digital Twin concept for SAF is proposed and demonstrated, linking together information from models and data to form a virtual representation of the fuel and mirror the fuel during its lifecycle. Special emphasis is placed on the representation of uncertainties of the involved model predictions and the traceability of the provenance of all information within the Digital Twin. The methodology is tested and demonstrated for a decision making problem typical for the utilization of SAF under the current regulatory constraints, namely the blending of conventional fuel with SAF to a drop-in SAF blend. The fact that the physical properties of the conventional jet fuel might vary within its specification requires a careful selection of the blend ratio and the candidate SAF to achieve an optimal blend given associated cost functions and constraints. It is identified that due to the defined constraints and the cost function, not always the SAF with the highest possible blend ratio is selected as the best choice. It is shown that the inclusion of uncertainties narrows the range of possible blend ratios and hence affects the decision process and the optimal decision. However, this approach reflects a risk-informed decision since uncertainties in the model prediction are considered in the decision process.

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Assessment of the Comparability of Droplet Evaporation Fuel Sensitivities between a Unit Test Case and an Aviation Gas Turbine Combustor

Cited by 4 publications

References 17 publications

Numerical Simulation and Uncertainty Quantification of a Generic Droplet Evaporation Validation Test Case

Numerical Simulation and Uncertainty Quantification of a Generic Droplet Evaporation Validation Test Case

Measurement of evaporation of hydrocarbon droplets by laser absorption spectroscopy

A proposed Digital Twin concept for the smart utilization of Sustainable Aviation Fuels

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