You Do Need power plug adapter while traveling from Sudan to Namibia.

Here is Why You Need An Adapter

The outlet and plug type used in Namibia are D and M and in Sudan are C and D. This is how they look like.

Sudan

In Sudan, outlets of type C and D are in use.

Type C

Type D

Namibia

In Namibia, outlets of type D and M are in use.

Type D

Type M