Transcritical film cooling was investigated by numerical study in a methane cooled methane/oxygen rocket engine.The respective time-averaged Navier-Stokes equations have been solved for the compressible steady three-dimensional(3-D) flow.The flow field computations were performed using the semi-implicit method for pressure linked equation(SIMPLE) algorithm on several blocks of nonuniform collocated grid.The calculation was conducted over a pressure range of 202 650.0 Pa to 1.2×107 Pa and a temperature range of 120.0 K to 3 568.0 K.Twenty-nine different cases were simulated to calculate the impact of different factors.The results show that mass flow rate,length,diameter,number and diffused or convergence of film jet channel,injection angle and jet array arrangements have great impact on transcritical film cooling effectiveness.Furthermore,shape of the jet holes and jet and crossflow turbulence also affect the wall temperature distribution.Two rows of film arranged in different axial angles and staggered arrangement were proposed as new liquid film arrangement.Different radial angles have impact on the film cooling effectiveness in two row-jets cooled cases.The case of in-line and staggered arrangement are almost the same in the region before the second row of jets,but a staggered arrangement has a higher film cooling effectiveness from the second row of jets. Transcritical film cooling was investigated by numerical study in a methane cooled methane / oxygen rocket engine. These were time-averaged Navier-Stokes equations have been solved for the compressible steady three-dimensional (3-D) flow. Flow field computations were performed using the semi-implicit method for pressure linked equation (SIMPLE) algorithm on several blocks of nonuniform collocated grid. The calculation was conducted over a pressure range of 202 650.0 Pa to 1.2 × 107 Pa and a temperature range of 120.0 K to 3 568.0 K Twenty-nine different cases were simulated to calculate the impact of different factors. The results show that mass flow rate, length, diameter, number and diffused or convergence of film jet channel, injection angle and jet array arrangements have great impact on transcritical film cooling effectiveness. Focus of shape of the jet holes and jet and crossflow turbulence also affect the wall temperature distribution. Two rows of film arrangement in different axial an gles and staggered arrangement were proposed as new liquid film arrangement.Different radial angles have impact on the film cooling effectiveness in two row-jets cooled cases.The case of in-line and staggered arrangement are almost the same in the region before the second row of jets, but a staggered arrangement has a higher film cooling effectiveness from the second row of jets.