373
Views
3
CrossRef citations to date
0
Altmetric
Research Article

Numerical Simulation of n-Heptane Spray Combustion in a Porous Medium Burner

ORCID Icon, ORCID Icon, , &
Pages 313-334 | Received 07 May 2021, Accepted 29 Jun 2021, Published online: 07 Jul 2021
 

ABSTRACT

A two-dimensional numerical simulation study is conducted to investigate the combustion process of n-heptane spray in a porous medium burner (PMB) based on the previous experimental work performed by this research group. In order to adapt the model for the conditions of different wall temperatures and different splash Mach numbers, the wall-impingement model in this study is based on the model by O’Rourke and Amsden and the interaction mechanism between the spray droplets and the wall is optimized through user-defined functions (UDFs). The effects of air inlet velocity, injected fuel quantity and preheating temperature on spray combustion are analyzed. The results show that the downstream velocity of the combustion flame increases when the inlet air velocity increases or the fuel injection rate decreases or the preheating temperature decreases. Under the same equivalence ratios, the flame propagation velocity increases as the increase of the dimensionless gas-oil joint effect parameter. The flame area also increases with the increase of inlet air velocity, but the rate of increase in the flame area gradually decreases as the reaction proceeds. An initial preheating temperature of 1060 K is conducive to the stable combustion of n-heptane spray for flame lengths less than 0.060 m.

Nomenclature

X length in the X direction (m)

Y length in the Y direction (m)

Qf quantity of fuel injected (kg/s)

Vair inlet air velocity (m/s)

T preheating temperature (K)

Yi mass fraction of component i

Di diffusion coefficient of component i (m2/s)

Wi molecular mass of component i (kg/kmol)

vi velocity vector of component i (m/s)

vp droplet velocity vector (m/s)

v fluctuating gas flow velocity (m/s)

CD drag coefficient

Twall temperature of the PM wall (K)

E splash Mach number

Vpn normal impact velocity of droplet (m/s)

dp droplet diameter (m)

h0 thickness of the liquid film (m)

Tcrit critical wall temperature (K)

Tcrit 1.27

Tsat saturation temperature of n-heptane (K)

Tmax maximum flame temperature (K)

ys mass ratio of splashed droplets

Greek symbols

ԑ porosity of porous medium

ρg gas density (kg/m3)

ρp droplet density (kg/m3)

σp droplet surface tension (N/m)

δbl thickness of the boundary layer (m)

φ equivalence ratio

ωi reaction rate of component i (kg/m2/s)

ψ azimuth angle (°)

β axial to radial maximum velocity ratio

θ1 dimensionless injected fuel quantity

θ2 dimensionless inlet velocity

θ3 dimensionless gas-oil joint effect parameter

Acknowledgments

This study was funded by the National Natural Science Foundation of China (Nos. 51576029 and 51476017).

Disclosure statement

No potential conflict of interest was reported by the author(s).

Additional information

Funding

This work was supported by the National Natural Science Foundation of China [51476017,51576029].

Reprints and Corporate Permissions

Please note: Selecting permissions does not provide access to the full text of the article, please see our help page How do I view content?

To request a reprint or corporate permissions for this article, please click on the relevant link below:

Academic Permissions

Please note: Selecting permissions does not provide access to the full text of the article, please see our help page How do I view content?

Obtain permissions instantly via Rightslink by clicking on the button below:

If you are unable to obtain permissions via Rightslink, please complete and submit this Permissions form. For more information, please visit our Permissions help page.