Short answer : NO
Long answer:
Only way of directly installing an .ipa file from internet to your iPhone is when you have a link to an ipa file which has been published using an enterprise ad-hoc license. In that case you can directly download ipa files from internet and install without any hassle. Testflight uses this similar concept for beta testing ipa files.
Otherwise you need to downlaod the ipa file into your iTunes Software and sync it to your phone. Still app works only if that ipa file has been purchased from your apple id before.(eg: ipa transferred to another computer). Or, if that ipa file contains UDID of your device (this is how we beta test ipa files normal way).
If you never purchased the app (.ipa) or does not have your UDID embeded in the ipa itself, no .ipa file works for your phone unless your phone is jailbroken and required cydia packages are already installed (illegal way).