Researchers across the world are exploring the potential of using diethyl ether as an alternate fuel to meet the stringent emission norms due to the high oxygen content in the fuel. The spray characteristics of any injected fuel are highly influenced by its physical properties. Due to high injection pressure in CI engines the fuel tends to cavitate inside the nozzle greatly. The change in fuel properties will affect the cavitating behavior of the fuel. In this paper computational technique is used to study and compare the internal flow characteristics of a fuel injector for different blends of diethyl ether and diesel fuel. Multi phase flow model considering the fuel as a mixture of vapor and liquid is adopted for the simulation study. The percentage volume of diethyl ether is varied from 0 to 100% and the flow characteristics are studied. Results indicate that as the percentage volume of diethyl ether increases in the fuel, the cavitating phenomenon also increases resulting in decrease in mass of fuel injected into the cylinder.