A compound engine assembly comprising: a compressor; an engine core including at least one internal combustion engine each having a rotor sealingly and rotationally received within a respective internal cavity to provide rotating chambers of variable volume in the respective internal cavity, the engine core having an inlet in fluid communication with an outlet of the compressor; a turbine section having an inlet in fluid communication with an outlet of the engine core, the turbine section configured to compound power with the engine core; and at least one heat exchanger (72, 74); and characterised by further comprising: a common air conduit having an inlet in fluid communication with ambient air around the compound engine assembly, the common air conduit in fluid communication with an inlet of the compressor and with the at least one heat exchanger (72, 74), the at least one heat exchanger (72, 74) configured to circulate a fluid of the engine assembly in heat exchange relationship with an airflow from the common air conduit circulating therethrough; wherein the at least one heat exchanger (72, 74) extends across the air conduit, such that the airflow through the air conduit circulates through the at least one heat exchanger; wherein the inlet of the compressor is in fluid communication with the common air conduit through an intake conduit connected to the common air conduit upstream of the at least one heat exchanger (72, 74), and a junction between the intake conduit and the common air conduit is configured as an inertial particle separator, the intake conduit defining a sharp turn with respect to the common air conduit. a compressor; an engine core including at least one internal combustion engine each having a rotor sealingly and rotationally received within a respective internal cavity to provide rotating chambers of variable volume in the respective internal cavity, the engine core having an inlet in fluid communication with an outlet of the compressor; a turbine section having an inlet in fluid communication with an outlet of the engine core, the turbine section configured to compound power with the engine core; and at least one heat exchanger (72, 74); and characterised by further comprising: a common air conduit having an inlet in fluid communication with ambient air around the compound engine assembly, the common air conduit in fluid communication with an inlet of the compressor and with the at least one heat exchanger (72, 74), the at least one heat exchanger (72, 74) configured to circulate a fluid of the engine assembly in heat exchange relationship with an airflow from the common air conduit circulating therethrough; wherein the at least one heat exchanger (72, 74) extends across the air conduit, such that the airflow through the air conduit circulates through the at least one heat exchanger; wherein the inlet of the compressor is in fluid communication with the common air conduit through an intake conduit connected to the common air conduit upstream of the at least one heat exchanger (72, 74), and a junction between the intake conduit and the common air conduit is configured as an inertial particle separator, the intake conduit defining a sharp turn with respect to the common air conduit. a common air conduit having an inlet in fluid communication with ambient air around the compound engine assembly, the common air conduit in fluid communication with an inlet of the compressor and with the at least one heat exchanger (72, 74), the at least one heat exchanger (72, 74) configured to circulate a fluid of the engine assembly in heat exchange relationship with an airflow from the common air conduit circulating therethrough; wherein the at least one heat exchanger (72, 74) extends across the air conduit, such that the airflow through the air conduit circulates through the at least one heat exchanger; wherein the inlet of the compressor is in fluid communication with the common air conduit through an intake conduit connected to the common air conduit upstream of the at least one heat exchanger (72, 74), and a junction between the intake conduit and the common air conduit is configured as an inertial particle separator, the intake conduit defining a sharp turn with respect to the common air conduit.