The 26-year-old, searching for a sixth consecutive win, beat Aaron Cheng in straight sets 21-8, 21-12 before a closer battle with Alex Marritt in which he triumphed 21-16, 21-11.
And Ouseph is hoping he can keep winning quickly in order to preserve his energy to add another national title to his already impressive haul.
"I'm looking to try and win as quick as I can, play as well as I can and try and save energy for later on in the tournament," said Ouseph, who represented Team GB at the London 2012 Olympics.
"It was quite comfortable, though my second match was a little harder than the morning. It was a bit more of a work-out.
"There is a little bit of me that wants to be tested, so I'm not rusty, but those matches were what I needed."
Ouseph, ranked 34 in the world, then sprung a shock when he and Carl Baxter knocked out full-time men's doubles pair and fourth seeds Ben Stawski and Gary Fox in the second round.
Meanwhile eighth-seed Sam Phillips lost in the first round of the men's singles to 17-year-old Alex Lane, who saw off his more experienced rival in three sets, but comfortably won the last 21-3.
Lane, who is reigning under-17 European champion, then dug deep into his reserves to beat Ben Muir inside three sets, eventually squeezing through 21-16 in the last.
Fourth-seed Ben Beckman and seventh-seed Robert Kettle also failed to make the quarter-finals, beaten by Sam Parsons and Rhys Walker respectively.
Toby Penty made it safely through to the last-eight with wins over Tom Stanford and Ollie Baczala, while sixth-seed Carl Baxter also booked his place in the quarter finals.
Women's top seed Elizabeth Cann breezed through her two rounds, the 33-year-old beat Lexi Gilders and Lynnlette Aung with dropping a set.
Mixed doubles pairing Chris Adcock and Gabby White, who are starting their path to Rio 2016 qualification, beat James Lauder and Zoe Hallam 21-5, 21-9 inside 15 minutes.
And Lauder was then beat again by Adcock who also eased through his men's doubles clash alongside Marcus Ellis, defeating him and partner Andrew Wainwright without losing a set.