When you blow the air into the pipe, the wedge which is placed in the pipe produces the oscillation of the air particles, so there will always be a motional antinode in this area of the pipe.

The other end of the pipe can be open or closed. The assist lines in the picture show the movement force of air particles. When the pipe is closed, the standing wave will have a node here, and when it is open an antinode will be formed in this place.

In the picture above, you can see the standing wave created in the closed pipe and in the picture below, the one formed in the open pipe.