Hi,

select c.value || '/' || 'ora_' ||
ltrim(to_char(a.spid,'fm99999')) || '.trc'
from v$process a, v$session b, v$parameter c, v$thread c
where a.addr = b.paddr
and b.audsid = userenv('sessionid')
and c.name = 'user_dump_dest'

gives trace filename for current session.