A cable bushing device is used to pass an electrical cable through, in particular, two adjacent housings which are explosion andor flame-proof. The rack includes a back wall defining an air outlet aligned with the server units. The primary flow nozzle includes a downstream edge portion that is either beveled with one or more beveled surfaces, or that contains a curving edge surface or a combination of a beveled edge and a curved edge to help direct noise generated by the jet engine upwardly away from a ground surface during take-off and landing procedures.