Is flow attached at fixed propeller blade at every RPM / speed conditions? Propeller blade AoA depends on tangential veloctiy caused by rotation and forward speed &quot;head wind&quot;.
If propeller has fixed pitch is flow attached  on blade at every RPM / speed conditions?
For example when plane has full throttle when staying on ground at same place,forward veloctiy is very small,that mean AoA is higher,does this cause flow separation at low pressure side of  blade  at this RPM/speed condition..etc
No, flow separation far away from the intended operating point is common.
Witness racing planes. Before Ratier made the first useable variable-pitch propellers in 1932, high speed aircraft had abysmally low propeller efficiencies at low speed, so much that world records were set with floatplanes (which had virtually unlimited &quot;airfields&quot; at their disposal). Same with small racing boats: To get over the hump (transition from buoyancy to planing), drivers need to lean forward and to patiently gain speed with their high-pitch propellers providing only marginal thrust due to flow separation.
The rotating movement of propeller blades helps to accelerate the boundary layer outwards, so flow separation on propellers happens much later (at more adverse pressure gradients) than on wings. Regardless, if blade angle and flow direction at the blade don't match well enough, separation is unavoidable.