I installed QlikSense 3.1.5 last week on a few servers and, for example, on my server number 4 pointed its data store to D:\QlikShare4\ which means the apps are held in :
D:\QlikShare4\Apps
So it depends on the install.
It stores them as files named as per the app id.
I'd advise extreme caution re these folders and files as it would be possible to ruin your Qlik Sense installation accidentally.