Harnoor hit 12 fours in his 101-ball knock while Angriksh found 10 boundaries and two sixes.
Stand-in skipper Nishant Sindhu (36 off 34; 5x4s) and Raj Bawa (42 off 64; 2x4s; 1x6) shared a 64-run stand for the third wicket, ensuring that the platform created by the openers was well-utilised to set a big score.
Just when it seemed India lacked enough firepower towards the end as big hits had dried up, Rajvardhan Hangargekar hit five sixes, including a hat-trick of maximums in the last over, in his fiery 17-ball 39-run unbeaten cameo that took India past the 300-run mark.
Harnoor, who has been in sparkling form, drove the ball elegantly. If it was pitched up on the middle and leg, the left-hander from Jalandhar flicked it exquisitely. The ones pitched up on the off-side were driven in the cover region as Harnoor ticked the board nicely.
In contrast, Angriksh chose to muscle the ball around. He cut, pulled and also drove in an aggressive manner as none of the Ireland bowlers could trouble the Indian openers.
The 16-year-old from Delhi pulled left-arm spinner Matthew Humphreys (1/69) over deep mid-wicket for a six to raise his half-century. It was the same bowler who trapped him leg before later.
Angkrish was dismissed by spinner Jamie Forbes (1/38).
Chasing 308, Ireland was teetering at 17 for three after losing both openers Liam Doherty (7), David Vincent (8) and one-down Jack Dickson (0) cheaply inside the first seven overs.
India bowl out Ireland for 133 to register their second win in the #U19CWC 2022!
They have won by 174 runs and qualified for the Super League phase.#INDvIRE pic.twitter.com/A9lcm3wUzn — Cricket World Cup (@cricketworldcup) January 19, 2022
Ireland never recovered from the early blows as right-arm medium pacer Garv Sangwan (2/23) sent back skipper Tim Tector (15) in the 15th over, to leave the side reeling at 36 for four.
Wicket-keeper Joshua Cox (28 off 46 balls) tried to take the game deep, but it was too little and too late.
Sangwan struck again, this time removing Cox, who was caught by Dinesh Bana in the 21st over as Ireland lost half its side for 66.
Scott Macbeth (32) only delayed the inevitable but from here on, it was just a matter of time and India folded up Ireland's innings for just 133 with left-arm orthodox spinner Aneeshwar Gautam (2/11) and off-spinner Kaushal Tambe (2/8) cleaning up the lower middle order and tail-enders.
For India, Sangwan, Gautam and Tambe picked two wickets each while Rajvardhan Hangargekar (1/17), Ravi Kumar (1/11) and spinner Vicky Ostwal (1/22) too played their parts to perfection.
India now need to have enough players for their last Group B game against Uganda on Saturday as besides Dhull and Rasheed, batter Aaradhya Yadav, Vasu Vats, Manav Parakh, and Siddharth Yadav also tested positive for the virus