Turbulent　jet　ignition　(TJI)　is　an　advanced　ignition　mode　that　can　enhance　ignition　and　combustion　performance,　and　it　is　a　potential　ignition　strategy　for　ammonia/hydrogen　internal　combustion　engines.　This　study　aims　to　investigate　the　ignition　and　combustion　characteristics　of　lean　ammonia/hydrogen/air　ignited　by　TJI,　and　the　different　ignition　modes　were　compared.　The　results　indicate　that　active　TJI　with　auxiliary　hydrogen　injection　in　the　pre-chamber　improves　the　ignition　and　combustion　performance　of　ammonia/hydrogen/air,　and　the　appropriate　shift　of　the　pre-chamber　equivalence　ratio　towards　the　rich　side　is　considered　optimal.　As　the　ammonia　fraction　increases,　the　ignition　mechanism　in　the　main　chamber　changes　from　flame　ignition　to　jet　ignition.　The　advantage　of　TJI　is　mainly　shown　in　high　ammonia　fraction　mixtures,　which　is　reflected　in　significantly　lower　ignition　delay　and　combustion　duration.　In　addition,　TJI　reduces　the　sensitivity　of　combustion　to　ammonia　fraction　compared　to　SI,　due　to　the　high　ignition　energy,　initial　flame　area　and　turbulence　provided　by　the　hot　jet.　In　TJI　mode,　the　increase　in　jet　velocity　seems　to　be　detrimental　to　the　radial　development　of　flames　near　the　orifice,　which　may　result　in　an　increase　in　the　duration　of　the　final　stage　of　combustion.　©　2024　Elsevier　Ltd