Vertical packaging machine for packaging products, comprising a forming element with an upper mouth; a hopper which is arranged upstream of the forming element and aligned with said forming element and comprises an upper mouth through which the products to be packaged are introduced, at least the hopper and the forming element forming a vertical supply conduit through which the product to be packaged falls; a flow generator comprising an injection device configured for injecting a gaseous fluid and a distributor configured for directing said fluid to the supply conduit; and a control device configured for causing the injection device to inject the fluid in a controlled manner, the distributor comprising at least one inlet mouth communicated with the injection device for receiving the fluid injected by said injection device, and at least one outlet mouth in the supply conduit, which is communicated with the inlet mouth and arranged upstream of the upper mouth of the forming element and downstream of the upper mouth of the hopper, and which is configured for causing the injected fluid to be introduced downwards into said supply conduit, the outlet mouth comprising an area smaller than the area of the inlet mouth, such that when said fluid is introduced into the supply conduit it furthermore causes at least part of the air present in said supply conduit above the outlet mouth to be directed also towards the forming element following the injected fluid, and the control device being configured for causing the injection device to perform fluid injection of a specific duration for each product to be packaged in one and the same package, characterised in that the control device is further configured for causing said injection device to perform each fluid injection such that said injected fluid starts to reach the upper mouth of the forming element before all the product to be packaged in one and the same package has completely passed through the height of the outlet mouth and finishes reaching the upper mouth of the forming element once all the product has gone through said upper mouth. a forming element with an upper mouth; a hopper which is arranged upstream of the forming element and aligned with said forming element and comprises an upper mouth through which the products to be packaged are introduced, at least the hopper and the forming element forming a vertical supply conduit through which the product to be packaged falls; a flow generator comprising an injection device configured for injecting a gaseous fluid and a distributor configured for directing said fluid to the supply conduit; and a control device configured for causing the injection device to inject the fluid in a controlled manner, the distributor comprising at least one inlet mouth communicated with the injection device for receiving the fluid injected by said injection device, and at least one outlet mouth in the supply conduit, which is communicated with the inlet mouth and arranged upstream of the upper mouth of the forming element and downstream of the upper mouth of the hopper, and which is configured for causing the injected fluid to be introduced downwards into said supply conduit, the outlet mouth comprising an area smaller than the area of the inlet mouth, such that when said fluid is introduced into the supply conduit it furthermore causes at least part of the air present in said supply conduit above the outlet mouth to be directed also towards the forming element following the injected fluid, and the control device being configured for causing the injection device to perform fluid injection of a specific duration for each product to be packaged in one and the same package, characterised in that the control device is further configured for causing said injection device to perform each fluid injection such that said injected fluid starts to reach the upper mouth of the forming element before all the product to be packaged in one and the same package has completely passed through the height of the outlet mouth and finishes reaching the upper mouth of the forming element once all the product has gone through said upper mouth.