Abstract: The present study systematically investigated the statistical properties of the free air jets issuing from isosceles triangular orifices with apex angles of 30, 60 and 90°. The velocity was measured by a hot-wire anemometer at the exiting Reynolds number (Re) being 15000 for all jets, based on the equivalent diameter of the triangular orifices. The results show that the centreline mean velocity decays faster and turbulence intensity grows higher as AR decays. With jet flows developing downstream, the turbulence energy spectrum, probability density function and turbulence length scales of triangular jets approach to those of circular jets.