An aerosol-generating system comprising: a cartridge comprising: a cartridge housing defining a cartridge air inlet and cartridge air outlet, the cartridge air inlet extending through a wall portion of the cartridge housing; and a solid aerosol-forming substrate positioned within the cartridge housing; a vaporiser section comprising: a vaporiser housing defining a vaporiser air inlet and a vaporiser air outlet, the vaporiser air outlet extending through a wall portion of the vaporiser housing, the vaporiser housing configured to receive at least a portion of the cartridge; and an electric heater and a liquid aerosol-forming substrate each positioned within the vaporiser housing; wherein the cartridge and the vaporiser section are configured so that the cartridge housing wall portion abuts the vaporiser housing wall portion when the vaporiser section receives the cartridge; and wherein a rotational orientation of the cartridge with respect to the vaporiser section is variable, the amount of overlap between the cartridge air inlet and the vaporiser air outlet being variable between different rotational orientations; and a power supply section comprising a power supply for supplying electrical power to the electric heater. a cartridge comprising: a cartridge housing defining a cartridge air inlet and cartridge air outlet, the cartridge air inlet extending through a wall portion of the cartridge housing; and a solid aerosol-forming substrate positioned within the cartridge housing; a cartridge housing defining a cartridge air inlet and cartridge air outlet, the cartridge air inlet extending through a wall portion of the cartridge housing; and a solid aerosol-forming substrate positioned within the cartridge housing; a vaporiser section comprising: a vaporiser housing defining a vaporiser air inlet and a vaporiser air outlet, the vaporiser air outlet extending through a wall portion of the vaporiser housing, the vaporiser housing configured to receive at least a portion of the cartridge; and an electric heater and a liquid aerosol-forming substrate each positioned within the vaporiser housing; wherein the cartridge and the vaporiser section are configured so that the cartridge housing wall portion abuts the vaporiser housing wall portion when the vaporiser section receives the cartridge; and wherein a rotational orientation of the cartridge with respect to the vaporiser section is variable, the amount of overlap between the cartridge air inlet and the vaporiser air outlet being variable between different rotational orientations; and a vaporiser housing defining a vaporiser air inlet and a vaporiser air outlet, the vaporiser air outlet extending through a wall portion of the vaporiser housing, the vaporiser housing configured to receive at least a portion of the cartridge; and an electric heater and a liquid aerosol-forming substrate each positioned within the vaporiser housing; wherein the cartridge and the vaporiser section are configured so that the cartridge housing wall portion abuts the vaporiser housing wall portion when the vaporiser section receives the cartridge; and wherein a rotational orientation of the cartridge with respect to the vaporiser section is variable, the amount of overlap between the cartridge air inlet and the vaporiser air outlet being variable between different rotational orientations; and a power supply section comprising a power supply for supplying electrical power to the electric heater.