The theoretical analysis of a two‐dimensional jet of ideal fluid impinging normally upon a void has been made and compared with experimental observations. Using a scaled‐up water model with a fixed‐jet Reynolds number of 750, general features of the flow such as streamline positions and fluid velocities are in good agreement with theoretical predictions. Moreover, theoretical limitations on the void‐space opening ratioh/wfor a given jet spacing ratios/wcovering a range from 0 to 2 correlate well with the onset of irregularities in the observed flow pattern. Finally, experimental precautions are outlined necessary to minimize fluid instabilities and concurrent fluid flux into the void space.