During　the　fuel　injection　process　of　a　common　rail　(CR)　fuel　system,　submerged　jet　occurs　in　the　injector　control　valve.　Different　with　the　free　jet　of　the　nozzle,　this　submerged　jet　determines　the　needle　movement　and　causes　great　effects　on　the　fuel　injection.　This　work　presents　an　investigation　on　the　submerged　jet　characteristics　of　a　cylindrical　orifice　under　conditions　of　varied　boundary　pressures.　An　optical　test　rig　is　used　to　examine　the　submerged　jet,　and　a　three-dimension　numerical　model　is　built　to　investigate　the　details　of　the　submerged　jet.　The　results　reveal　that　for　a　given　inlet　pressure,　as　the　back　pressure　declines,　bubbles　incept　at　the　orifice　inlet,　then　develop　to　the　orifice　outlet,　and　finally　jet　into　the　background　liquid.　The　development　process　of　the　impingement　force　is　divided　into　three　periods.　This　downstream　three-period　impingent　force　results　from　the　upstream　cavitation　flow.　The　crucial　turning　points　(such　as　the　cavitation　inception,　choking,　cavitation　at　the　orifice　outlet)　of　the　downstream　impingent　force　coincide　with　those　of　the　incoming　energy　such　as　the　liquid　momentum　flux,　the　turbulence　kinetic　energy.　Further,　the　developing　tendency　of　the　downstream　impingent　force　is　similar　to　those　of　the　incoming　energy.　(C)　2018　Elsevier　Ltd.　All　rights　reserved.