I would like to know that if Ubuntu can be installed on an Android phone without wiping out the current installation. Something like the Live CD for desktops?
Depends on the app. Go to Google Play store and search under "Linux" and "Ubuntu". As an example "Linux Deploy" seems to be a good app.
If you have a Galaxy Nexus you can go to http://www.ubuntu.com/phone/install but this will replace your Android OS
If your just interested in testing things out try an Ubuntu Phone emulator: http://www.omgubuntu.co.uk/2013/11/ubuntu-touch-emulator-released