ORCID Profile
0000-0003-4901-4668
Current Organisations
The University of Edinburgh
,
Beihang University
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Publisher: Elsevier BV
Date: 03-2015
Publisher: Elsevier BV
Date: 08-2019
Publisher: Elsevier BV
Date: 11-2023
Publisher: Elsevier BV
Date: 2019
Publisher: Elsevier BV
Date: 2021
Publisher: Elsevier BV
Date: 11-2014
Publisher: Elsevier BV
Date: 07-2023
Publisher: Elsevier BV
Date: 03-2020
Publisher: Elsevier BV
Date: 2023
Publisher: Elsevier BV
Date: 2023
Publisher: Elsevier BV
Date: 2021
Publisher: Elsevier BV
Date: 10-2015
Publisher: Elsevier BV
Date: 2019
Publisher: Elsevier BV
Date: 2019
Publisher: Elsevier BV
Date: 12-2023
Publisher: Elsevier BV
Date: 05-2015
Publisher: Elsevier BV
Date: 2023
Publisher: AIP Publishing
Date: 11-2022
DOI: 10.1063/5.0121889
Abstract: The combined effects of radiative heat loss, curvature, and preferential diffusion on laminar non-premixed flames (or flamelets) are investigated in this work by using asymptotic analysis. A general theoretical description of flame temperature and extinction is derived for curved flames with non-unity Lewis numbers and radiative heat loss. Special attention is paid to the effects of curvature and radiative heat loss on the flammability limits. The results show that (1) a curved flamelet always has two extinction limits: one is the kinetic extinction limit, and the other is the curvature-induced extinction limit for the adiabatic case or the radiative extinction limit for the radiative case (2) the curvature exerts a different influence on the adiabatic and radiative flames. Specifically for the adiabatic flame, it is found that both flame temperature and flame position significantly decrease as the curvature increases and that a new extinction limit at a low stretch rate occurs due to the existence of curvature. Furthermore, a higher curvature coupled with the increase in the Lewis number results in a lower flammability limit and narrower flammable zone. Therefore, the presence of curvature has a negative impact on the adiabatic flame. On the contrary, for the radiative flame, the results show that the increase in curvature has a positive effect on the flammability limit and thereby increases the flammable zone. It is expected that curved flamelets hold smaller (larger) flammable zones than planar flamelets under the adiabatic (radiative) condition. All results show that the change in flame curvature has a stronger effect on the flame structure and extinction than the deviation of the Lewis number from unity.
Publisher: Elsevier BV
Date: 08-2020
Publisher: Informa UK Limited
Date: 26-02-2015
Publisher: Elsevier BV
Date: 2019
Publisher: Elsevier BV
Date: 09-2016
Publisher: Elsevier BV
Date: 12-2023
Publisher: AIP Publishing
Date: 07-2022
DOI: 10.1063/5.0098382
Abstract: The Method of Moments (MOM) has largely been applied to investigate sooting laminar and turbulent flames. However, the classical MOM is not able to characterize a continuous particle size distribution (PSD). Without access to information on the PSD, it is difficult to accurately take into account particle oxidation, which is crucial for shrinking and eliminating soot particles. Recently, the Split-based Extended Quadrature Method of Moments (S-EQMOM) has been proposed as a numerically robust alternative to overcome this issue [Salenbauch et al., “A numerically robust method of moments with number density function reconstruction and its application to soot formation, growth, and oxidation,” J. Aerosol Sci. 128, 34–49 (2019)]. The main advantage is that a continuous particle number density function can be reconstructed by superimposing kernel density functions (KDFs). Moreover, the S-EQMOM primary nodes are determined in idually for each KDF, improving the moment realizability. In this work, the S-EQMOM is combined with a large eddy simulation resumed-probability density function flamelet rogress variable approach for predicting soot formation in the Delft Adelaide Flame III. The target flame features low/high sooting propensity/intermittency and comprehensive flow/scalar/soot data are available for model validation. Simulation results are compared with the experimental data for both the gas phase and the particulate phase. Good quantitative agreement has been obtained especially in terms of the soot volume fraction. The reconstructed PSD reveals predominantly unimodal/bimodal distributions in the first/downstream portion of this flame with particle diameters smaller than 100 nm. By investigating the instantaneous and statistical sooting behavior at the flame tip, it has been found that the experimentally observed soot intermittency is linked to mixture fraction fluctuations around its stoichiometric value that exhibits a bimodal probability density function.
Publisher: AIP Publishing
Date: 02-2023
DOI: 10.1063/5.0132024
Abstract: Bluff-body swirling flows have been widely employed in gas-turbine combustors to achieve flame stabilization. Meanwhile, considerable efforts have been made to understand swirling flow dynamics, the effects of swirl number and bluff body on flow structure and dynamics are still not well understood. To this end, a series of direct numerical simulations of isothermal swirling flows have been conducted in this work in order to investigate the impact of swirl numbers and bluff-body diameters on the flow structure, Reynolds stresses, and turbulent kinetic energy (TKE) transport. It is found that a change in the swirl number can affect the inner recirculation zone (IRZ) and hence momentum transport. Specifically, as the swirl number increases, the vortex core formed at downstream locations can merge with the IRZ. Moreover, including the bluff body not only contributes to the formation of the IRZ but also serves as a disturbance source for the flow, which is favorable for the formation of large-scale vortex structures. Then, the impact of swirl number and bluff body on Reynolds shear stresses and anisotropy invariants is investigated to identify the locations of the inter shear layer (ISL), the outer shear layer (OSL), and the main swirling zone (MSZ). The results show that as the swirl number increases, both the ISL and MSZ shift to the wall, indicating a large IRZ. Furthermore, the analysis of TKE indicates that for cases with a bluff body, TKE mainly occurs in the ISL and OSL, featuring a dual peak distribution. However, for cases without a bluff body, the distribution of TKE is primarily concentrated in the ISL. These results suggest that both increasing the swirl number and/or including the bluff body could help with TKE transport, which can lead to a wide range of TKE distribution.
Publisher: Elsevier BV
Date: 08-2018
Publisher: Elsevier BV
Date: 08-2016
Publisher: Elsevier BV
Date: 2023
Publisher: Elsevier BV
Date: 2023
Location: United Kingdom of Great Britain and Northern Ireland
No related grants have been discovered for Wang Han.