1. A lighting device comprising:a lighting module comprising:
a light-transmissive, elongated member having an inner surface which at least in part defines a light-guiding region within the elongated member; and
a plurality of light-emitting elements, each light-emitting element being configured to emit light, wherein the light-emitting elements are coupled to the inner surface of the elongated member such that an optical axis of at least one of the light-emitting element is non-perpendicular with respect to a longitudinal axis of the lighting module;
wherein the longitudinal axis of the lighting module is an axis of rotational symmetry of the lighting module such that the elongated member has a circular cross-sectional shape perpendicular to the longitudinal axis;
wherein the elongated member has at least a first end and a second end that are aligned along the longitudinal axis and are both open to permit passage of fluid therethrough and into and out of the first end and the second end, respectively;
the lighting device further comprising a light-transmissive envelope enclosing the lighting module; and
wherein the light-transmissive envelope defines a fluidly sealed and enclosed space within which the lighting module is arranged.