Hi,
You've got a couple of optins ...
You can install a fully seperate linux OS, there are hundreds available ...
You can install an actual version of Android, not a fan myself, but it's possible with help from several true Techie links online ...
And You could somply install either a "Virtual Machine" or USB bootable version of linux that will run when You only want to use the Android-based apps.
You can try several versions - including Android versions, as the USB bootable option by getting either "Universal USB Installer" or "YUMI Boot" from www.pendriveapps.com and then getting the correct ISO file for any version of linux You want to use with the Chromebook.
With the YUMI utility You can test as many as You like, wipe them off if they don't work, then try a few more ... until You find one that works with Your partyicular Chromebook hardware, and runs Your particular Android apps.
And as long as the linux distro doesn't want to take over Your harddrive (it will run in live mode) You can use them without disturbing the files on Your current system as long as You're careful not to "partition a drive", etc..
G'Luck!!