Cavitation of JP-8 fuel in a converging-diverging nozzle: experiments and modeling

This paper presents the results of an experimental investigation and an attempt to model cavitation of gas turbine aviation fuel. The work is motivated by the need to predict cavitation behavior for the design of modern aircraft fuel systems. Fuel cavitation can lead to unexpected degradation in system performance due to the effective compressibility associated with the formation of a two-phase mixture and/or damage of fuel system components due to subsequent bubble collapse. The primary working fluid for the experiments reported in this paper is JP- 8, which is the gas turbine fuel most typically used by the United States military. JP-8 consists of over 228 hydrocarbons and is closely related to Jet A-1, which is the most common commercial gas turbine fuel. Experiments are also performed with dodecane and decane which are two of the primary constituents of JP-8 by weight but have disparate vapor pressures. Following the experimental study by Davis [7,8], a two-dimensional converging-diverging (C-D) nozzle geometry was selected for this experimental investigation. This relatively simple geometry is nonetheless capable of producing many of the essential features of fuel cavitation, including compressibility, choking, bubbly shock formation, and bubble collapse. In this paper, streamwise nozzle pressure distributions are presented for choked cavitating nozzle flows with water, JP-8, dodecane and decane the working fluids. An analytical model is developed which is shown capable of duplicating many essential features of the measured nozzle pressure distributions including streamwise location of a bubbly shock and the associated pressure jump.