A combustion experiment has been installed in a test-cell for ignition and operability testing. The experiment operates on gaseous hydrogen fuel that is supplied to the experiment through a calibrated flow orifice for fuel metering. The fuel is supplied to the laboratory at 2200 psia and 45°F, where it is moved through a series of pipes or tubes with the following diameters and number of parallel lines before being injected into the experiment that operates at atmospheric pressure. Station 1 2 3 4 5
Supply Orifice Feed lines Injectors Exp/Lab
Dia[in] 1.5 0.252 0.25 0.020
Area[in^2]
# of lines 1 1 5 50
Mach 1 1
Po[pisa] 700
To[F] 90
P[pisa] 14.7
T[F]

Assuming that the mass ï¬ow through the system is to be determined by the upstream metering oriï¬ce, determine the following:

a. The critical pressure ratio that must be present across both the calibrated oriï¬ce or the fuel injectors to choke the ï¬ow through these areas.
b. The mass ï¬ow rate through the metering oriï¬ce for the given supply conditions and oriï¬ce area.
c. The stagnation pressure present in the Feed Lines required to supply the Fuel Injectors with enough pressure to ï¬ow the metered mass ï¬ow rate.
d. If the required critical pressure ratio will be present across the metering oriï¬ce to ensure sonic conditions when the fuel injectors are choked downstream, after calculating the Mach number and static pressure in the Feed Lines, Station #3,.
e. If the fuel ï¬ow to the experiment is accurately metered at the oriï¬ce, and what can be changed to allow correct fuel ï¬ow control.