Smith, W. and Timoney, D., "Fuel Injection Rate Analysis - A New Diagnostic Tool for Combustion Research," SAE Technical Paper 922224, 1992, doi:10.4271/922224.
This paper presents a new approach to the problem of determining instantaneous rates of fuel injection in direct injection diesel engines. A computer-based analysis tool has been developed which uses experimental data for fuel line pressure (measured at any point downstream of the fuel pump), needle lift and cylinder pressure as inputs to a fluid flow calculation routine. This uses a “method of characteristics” solution to the equations governing unsteady, one-dimensional flow of a compressible liquid in the fuel line and within the injector body. The technique can be used to determine instantaneous injection rates on a cycle-by-cycle basis in a running engine.