Ankara University has two semesters at one academic year. Fall Semester starts at September and Spring Semester starts at February.
Undergraduate programs has only one intake term for one academic year which is at June-August of each year. Detailed announcement about application process is made by Students Affairs Office from oidb.ankara.edu.tr at April or May of each year.
Graduate degree applications can be done for each semester. For Fall Semester, applications is at June-August of each year and for Spring Semester, applications is at January of each year. Announcements about quotas and special conditions is made by each graduate school from their own web sites.
You can find current application requirements and quotas from http://oidb.ankara.edu.tr/ and web sites of graduated schools.