Fuel injection System

Design

Final Design

Control and Analysis Systems

            For a successful experiment as much data as possible should be gathered from the design during the test runs.  The most important variable during the test is the pressure of the fuel at key points in the device.  As such at least one pressure transducer should be used.  Most pressure transducers work by reading the strain on a diaphragm which is in contact with the pressurized material, in this case JP-10.  The strain data is read as a voltage, which is passed along the line to a data collecting software suite.  A pressure transducer such as this can read the pressure of the fuel as it moves through the ½ inch diameter piping.  This data can be used to find any problems in the system as well as to ensure that the sprays are as consistent as possible.  One transducer should be placed immediately upstream of the solenoid valve, with a second, optional transducer being placed between the nozzle and the valve. 

One pressure transducer which would work well is the Omega PX209-200G5V.  This pressure transducer has a maximum pressure of 200 psi, a reaction time of approximately .003 seconds, and has been used for fuel pressure readings of jet fuel.  It is preferable that, when mounted, as little as possible of the transducer’s sensor tip is in the flow of the JP-10.  This creates a problem in that the pressure transducer’s tip is flat and is to be mounted in the side of a round steel pipe.  Further more, the steel pipe will not have a wall thickness that is thick enough to securely fasten all of the threads on the transducer’s tip.  In order to solve these problems a cubic stud should be welded to pipe, in the center of which a ¼ inch hole is to be drilled and tapped to accept the ¼-18 NPT threading of the pressure transducer.  The stud should be thick enough that the pressure port in the transducer is in line with the inner radius of the pipe.  Doing so will allow the transducer to read accurately, but will keep it out of the way of the fluid flow so as to reduce any further head loss in the system.  Omega Co.’s website’s Adobe file is found in Appendix A, Figures 2 and 3.

Further data gathering devices could be added during the testing of the device and the flexibility to do so will also be important.