Tracer particle spreading device, tracer particle spreading system and wind tunnel test system

The invention provides a tracer particle spreading device, a tracer particle spreading system and a wind tunnel test system. The tracer particle spreading device comprises a particle input tube that is disposed outside an airflow flow input tube and is used for inputting tracer particles and a nozzle that is communicated with the output terminal of the particle input tube and extends into a mixingcavity of a mixing tube. The nozzle spreads tracer particles outputted by the particle input tube uniformly into the mixing cavity of the mixing tube, so that the tracer particle and the airflow aremixed uniformly and then the mixture is outputted through an airflow output tube. The radial dimension of the inner cavity of the airflow input tube is smaller than that of the mixing cavity of the mixing tube, so that a backward step is formed at the communication position of the inner cavity of the airflow input tube and the mixing cavity of the mixing tube. The nozzle is arranged at the backward step, so that the mixing