x>0时 E=E-5 N,=P-P x<0时 01=OL 02=0L M=(E-)/2 △P=(P,+P)/2 x,>O时 阀口压差AP=(Ps-P)/2 Q.=CaWx(Ps-P.)/p x,<O时 阀口压差AP=(P+P)/2 .CaWxy(Ps-P)/pOL=CaWx(Ps +P)/p ( ) /  ( ) / 2 0 L d v S L S L v Q C Wx P P P P P x = −  = −  阀口压差时 x> 0 时 x< 0 时 ( )/  ( )/  ( )/ 2 0 L d v S L L d v S L S L v Q C Wx P P Q C Wx P P P P P x = − = +  = +  阀口压差时