An injection device that is configured for atomising a liquid into droplets by means of a gas, comprising - a hollow tubular body extending in a longitudinal direction and an inner wall of which defines a first zone referred to as a contact zone and a second zone located downstream of the first zone following a direction of circulation of liquid and gas inside the body, - a first gas introduction element for introducing a gas into the first zone in the longitudinal direction, said gas introduction element being mounted on a first opening of the body, at one end thereof in the longitudinal direction, - a second liquid introduction element for introducing a liquid into the first zone in a direction perpendicular to the longitudinal direction, mounted on a second opening of the body near the first opening, - an atomisation element mounted on a third opening of the body located opposite the second opening, comprising: - a tubular pipe for supplying gas into the first zone located opposite the liquid introduction element, and - a target located at the centre of the pipe, the pipe and the target extending in a direction perpendicular to the longitudinal direction, the target having an impact surface at one end of the pipe opening into the first zone, in alignment with the first gas introduction element, - an end member comprising at least one outlet for discharging the atomised liquid, mounted at one end of the body opposite the first gas inlet opening, characterised in that the body has an internal cross-section varying continuously or constantly over its entire length and in that its inner wall is provided, between the first and the second zone, with at least one baffle (26 i, 26' i, 26" i, 26"' i; 126, 126' i) projecting from the inner wall towards the interior of the body, the baffle(s) having a height, measured perpendicular to the longitudinal direction of the body, not equal to zero, equal to at least 1/10 th and at most 1/4 of the maximum internal dimension of the body perpendicular to the longitudinal direction of the body and said at least one baffle (26' i, 26" i, 26"' i) is configured so that, in each plane perpendicular to the longitudinal direction of the body containing said baffle, the latter extends over only a part of the periphery of the inner wall. - a hollow tubular body extending in a longitudinal direction and an inner wall of which defines a first zone referred to as a contact zone and a second zone located downstream of the first zone following a direction of circulation of liquid and gas inside the body, - a first gas introduction element for introducing a gas into the first zone in the longitudinal direction, said gas introduction element being mounted on a first opening of the body, at one end thereof in the longitudinal direction, - a second liquid introduction element for introducing a liquid into the first zone in a direction perpendicular to the longitudinal direction, mounted on a second opening of the body near the first opening, - an atomisation element mounted on a third opening of the body located opposite the second opening, comprising: - a tubular pipe for supplying gas into the first zone located opposite the liquid introduction element, and - a target located at the centre of the pipe, the pipe and the target extending in a direction perpendicular to the longitudinal direction, the target having an impact surface at one end of the pipe opening into the first zone, in alignment with the first gas introduction element, - a tubular pipe for supplying gas into the first zone located opposite the liquid introduction element, and - a target located at the centre of the pipe, the pipe and the target extending in a direction perpendicular to the longitudinal direction, the target having an impact surface at one end of the pipe opening into the first zone, in alignment with the first gas introduction element, - an end member comprising at least one outlet for discharging the atomised liquid, mounted at one end of the body opposite the first gas inlet opening,