1. A wire electrical discharge machine, comprising:a feed roller configured to feed a wire electrode toward a workpiece;
a collecting roller configured to collect the wire electrode having passed through the workpiece;
a guide member arranged on a path for feeding the wire electrode from the feed roller toward the workpiece and having therein a passage hole through which the wire electrode is passed;
an airflow generator configured to generate a flow of compressed air in the passage hole and to switch a flow direction of the compressed air flowing through the passage hole between a forward direction which corresponds to a feeding direction of the wire electrode and a reverse direction opposite to the feeding direction of the wire electrode;
a deflection detector configured to detect a deflection of the wire electrode; and
a control device configured to control the airflow generator so as to generate a flow of the compressed air in the forward direction in the passage hole during auto wire feeding and so as to, when the deflection detector detects the deflection, change the flow direction of the compressed air flowing through the passage hole to the reverse direction and thereafter switch the flow direction of the compressed air from the reverse direction to the forward direction,
wherein the airflow generator is configured to inject the compressed air into the passage hole from an outlet side for the wire electrode in the passage hole to direct the flow of the compressed air through the passage hole in the reverse direction,
the airflow generator includes a turbulence generating member configured to disturb the flow of the compressed air, the turbulence generating member being arranged on a flow path of the compressed air between the outlet side for the wire electrode in the passage hole and a position at which the compressed air is injected, wherein a tip of the wire electrode is moved irregularly at different positions by the disturbed flow of the compressed air.