The　dry　gas　seal　is　a　promising　sealing　technology　to　control　the　leakage　flow　through　the　clearance　between　the　stationary　and　rotational　components　of　Supercritical　Carbon　Dioxide　(SCO2)　turbomachinery.　The　dry　gas　seal　is　firstly　designed　for　the　SCO2　compressor　shaft　end　of　the　GE＇s　450MWe　Brayton　cycle　power　generation　system.　Then　the　effects　of　the　spiral　angle　and　gas　film　thickness　on　the　designed　dry　gas　seal　performance　are　numerically　investigated　using　the　three-dimensional　Reynolds-Averaged　Navier-Stokes　(RANS)　and　SST　turbulence　model.　The　accuracy　of　the　numerical　method　is　validated　by　comparison　of　the　previous　research　data　done　by　Gabriel　et　al.　with　air　as　the　working　fluid.　The　Current　study　analyzed　the　sealing　performance　parameters　of　the　designed　dry　gas　seal　for　SCO2　compressor　shaft　end　at　five　gas　film　thicknesses　and　four　spiral　angles.　These　parameters　include:　opening　force,　leakage　rate,　stiffness,　and　opening　force　leakage　ratio.　Also,　the　impacts　of　the　spiral　angle　on　flow　direction　in　the　fluid　film　are　analyzed.　The　obtained　results　show　that　the　designed　dry　gas　seal　meets　the　requirement　of　the　leakage　flow　rate　of　the　SCO2　compressor　shaft　end.　The　dry　gas　seal　with　a　spiral　angle　of　15°　is　the　best　solution　due　to　its　low　leakage　rate　and　its＇　best　comprehensive　sealing　performance.　On　some　occasions　where　high　stability　is　required,　the　dry　gas　seal　with　a　spiral　angle　of　30°　can　be　selected　due　to　its＇　highest　film　stiffness.　The　present　work　provides　the　reference　of　the　dry　gas　seal　design　for　the　SCO2　compressor　shaft　end.　Copyright　©　2020　ASME