Drill　strings　are　one　of　the　most.　significant　rotor　components　employed　in　oil　and　gas　exploitation.　In　this　paper,　an　improved　dynamical　model　of　drill-string-like　pipes　conveying　fluid　is　developed　by　taking　into　account　the　axial　spin,　fluid-structure　interaction　(FSI),　damping　as　well　as　curvature　and　inertia　nonlinearities.　The　partial　differential　equations　of　motion　are　derived　by　two　sequential　Euler　angles　and　the　Hamilton　principle　and　then　directly　handled　by　the　multiple　scales　method.　The　nonlinear　amplitudes,　frequencies　and　whirling　mode　shapes　are　all　investigated　towards　various　system　parameters　to　display　the　nonlinear　dynamical　characteristics　of　such　a　special　rotor　system　coupled　with　FSI.　It　is　revealed　that　the　nonlinear　amplitudes　and　frequencies　are　explicitly　dependent　on　the　spinning　speed,　while　the　flowing　fluid　mainly　contributes　to　the　linear　frequencies,　and　consequently　influences　the　nonlinear　amplitudes　and　frequencies.　The　PSI　effect　and　axial　spin　can　both　improve　the　forward　procession　mode　and　suppress　the　backward　one,　while　both　procession　modes　will　be　suppressed　by　the　viscoelastic　damping.　The　pipe　will　ultimately　present　a　forward　as　well　as　decayed　whirling　motion　for　the　fundamental　mode.