Hammer makes a total of three changes to his starting line-up with Davies in to partner Lewis Jones at half, with Rhys Patchell moving to full back for the league encounter.
Adam Thomas also moves position and into the outside centre jersey and will join forces with Gavin Evans in midfield. Smith provides the fire-power out wide with Alex Cuthbert on the other wing.
Navidi is named at openside flanker, in a back row that also contains Josh Turnbull and Manoa Vosawai, while hooker Matthew Rees will again captain the side.
New faces on the replacement bench this week include Rhys Williams, Ellis Jenkins and Geraint Walsh, who could make his debut for the region.
“This game will give us another clear indication of exactly where we are as a group and, during what has been a quick turnaround between games, the squad has trained exceptionally hard as we look forward to getting back out on the field,” said Hammer.
“In the short period of time I’ve been at Cardiff Blues, it has been pleasing to see that we have assembled a group of players who are prepared to work hard and are eager to learn.
“We have had to deal with adversity for the first time this season over the last week, but have responded by showing the right attitude and resolve. Now we need to take that mentality and determination over the whitewash and into the Ulster game.
“We have made some changes to the team and look forward to seeing those combinations,” he added. “We have an agreement with the union over Sam Warburton’s availability throughout the season and have decided to make changes in the back row this week to ensure we get the very best out of him in the long-term while also giving players like Josh Navidi a deserved chance to impress.”
Hammer has also urged rugby fans across the region to get right behind the Blues and create a special Friday night occasion adding: “The atmosphere at our opening home fixture against Glasgow was absolutely fantastic.
“It was great to see so many fans at BT Sport Cardiff Arms Park right behind us. That level of backing is always hugely appreciated and makes a huge difference to the players.”
The weekend starts here! Tickets remain on sale NOW for our home fixture with Ulster Rugby in the Guinness PRO12 this Friday. Call the Ticket Office on 02920 302030 or click HERE to buy online.
Cardiff Blues: 15 Rhys Patchell, 14 Alex Cuthbert, 13 Adam Thomas, 12 Gavin Evans, 11 Richard Smith, 10 Gareth Davies, 9 Lewis Jones; 1 Sam Hobbs, 2 Matthew Rees (c), 3 Adam Jones, 4 Jarrad Hoeata, 5 Filo Paulo, 6 Josh Turnbull, 7 Josh Navidi, 8 Manoa Vosawai
Replacements: 16 Rhys Williams, 17 Taufa’ao Filise, 18 Scott Andrews, 19 Macauley Cook, 20 Ellis Jenkins, 21 Lloyd Williams, 22 Cory Allen, 23 Geraint Walsh