Could be the CV joint is dry or has failed.
maybe the flap obove the left weel has com loose something youv left in te boot and forgotten about
Assuming this is an older car a knocking noise on turning could mean one of the drive shafts is worn. Other things to check - are the bolts tight on the front wheels, if a very high mileage it could be worn wheel bearings.
Wheel bearing?
honestly good question!,i have an 05 and mine does it too! my mechanic told me that its probably got a turn limiter that stops you before you can turn the car hard enuff to hurt it
Check the drive axle for a broken and leaking boot or bad CV joint.
Might be worn drive shafts or loose wheel nut
worn cv joint =[
Tie rod
Turning right loads the left front wheel of the vehicle, so if you hear the knock when you turn right the bad CV joint is on the left, and vice versa.
The outer CV joint could be on its way out, check to see if the rubber gaiter has gone - is cracked or perished as this lets water in and causes more wear. Should cost £80 - to £100 to fix.
a dog
Could be a bad CV joint or bad wheel bearing C.V. Joints need replacing