The surprise winners joined top seeded Ching-Wen Hsu of Taipei and eighth seed Karman Kaur Thandi in the semifinals.
Sri Vaishnavi defeated her more fancied rival and Fed Cupper Rishika 6-4 7-5 in 1 hour and 57 minutes.
In the toughest match of the day lasting over 2 hours and 20 minutes, Sowjanya sent Bhuvana packing 6-4 3-6 6-3.
Sowjanya, who won a USD 10,000 event in Aurangabad two years ago, broke her rival decisively in the 8th game of the third set to emerge winner .
In the semifinals Hsu will take on Sowjanya, while Sri Vaishnavi will clash with Karman.