  The study investigates the response dynamics of premixed jet flames when
incident with blast waves along the jet axis. In the present work, blast waves
are generated using the wire-explosion technique. The generated blast wave
interacts with premixed jet flames that are stabilised over a thin fuel-air jet
nozzle. The study is performed over a wide range of parametric space, varying
the Reynolds number ($Re$) and normalised equivalence ratio ($\Phi$) of the
premixed jet and the strength of the generated blast fronts ($M_{s,r}$). The
blast wave imposes a decaying flow field profile characterised by a sharp
discontinuity at the blast front. This is accompanied by a subsequent induced
flow arising due to entertainment from the surroundings as the blast-imposed
flow fields decay to sub-ambient levels. While the jet flame is observed to
respond to the blast front with a jittery motion, it is found to lift off
following the interaction with the induced flow. Depending on the operating
conditions ($Re$, $\Phi$, and $M_{s,r}$), the flame lift-off is followed by an
extinction or a re-attachment event. The flame response is further classified
into two re-attachment and three extinction sub-regimes based on the response
dynamics of the flame base and flame tip following the interaction process. The
flame response entails flame base lift-off and flame tip distortion,
potentially leading to a flame pinch-off event contingent on the operating
conditions. A mathematical model was developed to explain the flame base
response dynamics, yielding a scaling law for flame base lift-off height. Flame
tip response trends were elucidated by extending the vorticity transport
equation to estimate the vortex roll-up rate in the shear boundary surrounding
the flame. Flame pinch-off was observed when shear layer vortices reached
critical circulation limits and shed at length scales lower than the flame
height.
