Combustor and ammonia engine system

A combustor, comprising:

• a cylindrical housing having a first end and a second end, the first end being open and the second end being closed, and the housing being configured such that fuel mixed with oxidizing gas and combustion gas generated by combustion of the fuel flow through the housing;
• at least one inlet configured to introduce the fuel and the oxidizing gas into the housing such that a tubular flow is generated in the housing, the inlet being configured such that the tubular flow generates a negative pressure region in part of the housing;
• an ignition plug disposed at the second end of the housing and including a positive electrode and a negative electrode;
• and
• an ignition unit configured to generate a spark between the positive electrode and the negative electrode, wherein
• the positive electrode and the negative electrode are each located at a position where a distance between the positive electrode and the negative electrode is shorter than a distance between the positive electrode and an inner circumferential surface of the housing such that a flame generated between the positive electrode and the negative electrode by the spark is formed only in the negative pressure region.