Kapālabhātī refers to skull polishing, and is a pranayama (breathing) practice intended to energize and balance the nadis, and the chakras. Specifically, it is a sharp, short outbreath, followed by a relaxation of the core that allows the body to inhale on its own.
Naulī refers to intestinal cleansing. The practitioner stands with the feet about hip width apart, hands on knees, and body at about a 45 degree angle. The core is rotated internally by moving the abdominal muscles alternately in a clock-wise, then counterclock-wise direction.
^Muktibodhananda, Swami. (1985). Hatha Yoga Pradipika. New Delhi India: Thomson Press India, for The Yoga Publications Trust.
^These techniques and their practice are outlined in considerable detail by Swami Rama in his two volume set:
Rama, Swami. (1988). Path of Fire and Light, Volume I: Advanced Practices of Yoga. Honesdale, Pennsylvania. Himalayan Institute Press.
Rama, Swami. (1988). Path of Fire and Light, Volume II: A Practical Companion to Volume I. Honesdale, Pennsylvania. Himalayan Institute Press.