Time constants for the LB dynamic stall model updated based on a Leishman paper discussing the tuning of the model to match wind tunnel data for

an NREL airfoil... Still need to validate this (and BV dynamic stall model) against OSU data for Sandia airfoils, but it should be better than the original
model settings.

JCM

Author: jcokemurray

mod/dystl.f95

@@ -242,7 +242,7 @@ SUBROUTINE LB_UpdateStates(nb,nbe)
                 Tp=1.7                  ! time constant on LE pressure response to change in CL
                 TfRef=3.0               ! time constant on TE separation point travel
                 TvRef=6.0               ! time constant on LE vortex lift indicial function
-                TvL=5.25                ! Characteristic LE vortex travel time
+                TvL=11.0                ! Characteristic LE vortex travel time
 
                 ! Update states for each blade element
                 do i=1,nb                                                                                                     
@@ -285,31 +285,35 @@ SUBROUTINE LB_UpdateStates(nb,nbe)
                                         if (LESepState(nElem)==1) then
                                                 if (sLEv(nElem)<TvL) then
                                                         if (CLRateFlag(nElem)>0) then
-                                                                Tf=3*TfRef
+                                                                !Tf=3.0*TfRef ! original
+                                                                Tf=4.0*TfRef
                                                                 Tv=TvRef
 
                                                                 ! Set logic state flags (for model diagnosis output)
                                                                 LBLogicOutputs(nElem,8)=1
                                                         else
-                                                                Tf=1/2*TfRef
-                                                                Tv=1/2*TvRef
+                                                                Tf=1.0/2.0*TfRef
+                                                                Tv=1.0/2.0*TvRef
 
                                                                 ! Set logic state flags (for model diagnosis output)
                                                                 LBLogicOutputs(nElem,8)=2
                                                         end if
 
                                                         ! Set logic state flags (for model diagnosis output)
                                                         LBLogicOutputs(nElem,7)=1
-                                                else if (sLEv(nElem)<2*TvL) then
+                                                else if (sLEv(nElem)<2.0*TvL) then
                                                         if (CLRateFlag(nElem)>0) then
-                                                                Tf=1/3*TfRef
-                                                                Tv=1/4*TvRef
+                                                                ! orig 
+                                                                !Tf=1.0/3.0*TfRef
+                                                                !Tv=1.0/4.0*TvRef
+                                                                Tf=2.0*TfRef
+                                                                Tv=TvRef
 
                                                                 ! Set logic state flags (for model diagnosis output)
                                                                 LBLogicOutputs(nElem,8)=3
                                                         else
-                                                                Tf=1/2*TfRef
-                                                                Tv=1/2*TvRef
+                                                                Tf=1.0/2.0*TfRef
+                                                                Tv=1.0/2.0*TvRef
 
                                                                 ! Set logic state flags (for model diagnosis output)
                                                                 LBLogicOutputs(nElem,8)=4                                                        
@@ -318,8 +322,11 @@ SUBROUTINE LB_UpdateStates(nb,nbe)
                                                         ! Set logic state flags (for model diagnosis output)
                                                         LBLogicOutputs(nElem,7)=2                                                
                                                 else
-                                                        Tf=4*TfRef
-                                                        Tv=0.9*TvRef
+                                                        ! orig
+                                                        !Tf=4.0*TfRef
+                                                        !Tv=0.9*TvRef
+                                                        Tf=TfRef
+                                                        Tv=TvRef
 
                                                         ! Set logic state flags (for model diagnosis output)
                                                         LBLogicOutputs(nElem,7)=3

src/LB_DynStall.f95

@@ -18,7 +18,7 @@ SUBROUTINE LB_DynStall(nElem,CLstat,CDstat,alphaL,alpha5,umach,Re,SectInd,CL,CD)
         CLa = 2*pi
 
         ! Model constants
-        KD=.08                  ! TE separation drag factor
+        KD=.1                  ! TE separation drag factor
 
         ! Evaluate ideal CL curve at current AOA
         Call LB_EvalIdealCL(alphaL,AOA0,CLa,1,CLRef(nElem))