English (United Kingdom)

https://curated-unify.zendy.io/wp-json/zendy-region/v1/featured_content/oa?rat=en

https://curated-unify.zendy.io/wp-json/zendy-region/v1/highlighted_journal/

Zendy Plus

Presents the access of premium content as premium feature

Premium Content

Presents the keyphrase highlighting as premium feature

Keyphrase Highlighting

Presents the summarisation as premium feature

Summarisation

Insights

Presents the pdf analysis as premium feature

PDF Analysis

Presents the zaia usage as premium feature

ZAIA

Zendy Tools

Zendy Open

This paper investigates the initiation of a deflagration in a premixedboundary-layer stream by continuous heat deposition from a line energy sourceplaced perpendicular to the flow on the wall surface, a planar flowconfiguration relevant for small-scale combustion applications, includingportable rotary engines. Ignition is investigated in the constant densityapproximation with a one-step irreversible reaction with large activationenergy adopted for the chemistry description. The ratio of the characteristicstrain time, given by the inverse of the wall velocity gradient, to thecharacteristic deflagration residence time defines the relevant controllingDamk\"ohler number $D$. The time-dependent evolution following the activationof the heat source is obtained by numerical integration of the energy and fuelconservation equations. For sufficiently small values of $D$, the solution isseen to evolve towards a steady flow in which the chemical reaction remainsconfined to a finite near-source reactive kernel. This becomes increasinglyslender for increasing values of $D$, corresponding to smaller near-wallvelocities, until a critical value $D_{c1}$ is reached at which the confinedkernel is replaced by a steady anchored deflagration, assisted by the sourceheating rate, which develops indefinitely downstream. As the boundary-layervelocity gradient is further decreased, a second critical Damk\"ohler number$D_{c2}>D_{c1}$ is reached at which the energy deposition results in aflashback deflagration propagating upstream against the incoming flow along thebase of the boundary layer. The computations are extended to investigate thedependence of $D_{c1}$ and $D_{c2}$ on the fuel diffusivity as well as theadditional dependence of $D_{c1}$ on the source heating rate, therebydelineating the boundaries that define the relevant regime diagram for thesecombustion systems.

Regimes of boundary layer ignition by heat release from a localized energy source