Why is the flame of homemade alcohol stove too small?

I also made my own alcohol stove with cans. The same as yours. The flame is very low. Later, the joint of the two cans was sealed again. It is bonded with silica gel. The flame spraying effect is good. The original alcohol stove was not well sealed, leaked air and had no spraying effect. After strengthening the seal, the flame spraying effect is good. The flame height is 5- 10 cm. Looks a little scary.