如图所示输水管道。已知AB管段和CD管段长度lAB=lCD=400m,比阻aAB=aCD=0.23s²/m6.由节点B分出三根支管,在节点C汇合,各支管管长l₁=1000m,l₂=500m,l₃=800m;各支管比阻a₁=9.30s²/m6,a₂=1.07s²/m6,a₃=2.83s²/m6.若AB管段流量Q