Thank you for your question. If this is a one off one day travel then if your outward and return journey together amounts to 44 Kilometres and you do not return before zuhr, without doing anything to invalidate your fast, then you must not fast on the day of your journey. But you must not also break your fast if you travel after fajr and before zuhr until you have passed the permitted limit (definition below).
Below are the applicable rules according to the verdicts of Ayatullah Sistani. If there is still any confusion regarding your specific circumstances plz refer to the book Islamic Laws translated by Mohammad Ali Ismail in the sections of prayer for a traveller and laws of fasting for a traveller where the rulings are explained in greater detail.
May you always be successful
Ruling 1683. A traveller must not fast if his obligation on a journey is to perform the four unit (rakʿah) prayers as two rakʿahs [i.e. in qaṣr form]. A traveller who performs his prayer in its complete (tamām) form - such as someone whose work is travelling, or someone whose journey is a sinful one - must fast on his journey.
Ruling 1690. If a fasting person travels after ẓuhr, he must, based on obligatory precaution, complete his fast; and in such a case, it is not necessary for him to make up that fast; and if he travels before ẓuhr, then based on obligatory precaution, he cannot fast on that day, particularly if he had made the intention to travel the night before. In any case, he must not do anything that invalidates a fast before reaching the permitted limit (ḥadd al-tarakhkhuṣ), otherwise kaffārah becomes obligatory on him.
Ruling 1691. If a traveller in the month of Ramadan - whether he travelled before sunrise or he was fasting and then travelled - reaches his home town (waṭan) or a place where he intends to stay for ten days before ẓuhr, in the event that he did not do anything that invalidates a fast before reaching that place, he must, based on obligatory precaution, fast on that day and it is not obligatory on him to make it up; and if he did something that invalidates a fast before reaching that place, the fast of that day is not obligatory on
him and he must make it up.
PRAYERS OF A TRAVELLER
If the following eight conditions are fulfilled, a traveller must perform ẓuhr, ʿaṣr, and ʿishāʾ prayers in their shortened (qaṣr) form; i.e. he must perform them as two rakʿah prayers.
First condition: the journey must not be less than eight farsakhs (approximately forty-four kilometres) [which is equal to approximately twenty-seven and a half miles].
Ruling 1304. The permitted limit is the place where the people of a town - including those who live on its outskirts and are considered to be residents of the town - cannot see a traveller; and its sign is that he cannot see the people of the town.
