fa_total
Purpose:
-
Perform continuous fuel and air flow totalizing computations for engine performance, including summing rates and calculating metrics like air-fuel ratio.
Enter:
-
fa_total <priority> <interval> <filename> [+c]
Where:
-
priority
Specify the system task priority as an integer.
interval
Specify the process interval in milliseconds, such as FAS, MED, or SLO.
filename
Specify the path to the specification file.
+c
Optional. Specify this flag to indicate a critical task to the watchdog.
Example:
-
fa_total 8 1000 /specs/fa_specs.315 +c &
The above command spawns ‘fa_total’ in the background at a priority of 8.
The computations are performed once every second using the specifications
in the file /specs/fa_specs.315. The task is also assigned to be a critical
task. As a result, if the task ever stops responding to the watchdog, any
test that is running will be aborted. The fa_total task will register its
name with the filename (not the full pathame), in this case
“fa_specs.315”. This name can be used by the ‘re-read’ command to request
that it updates the specifications by reading the specification file again.
This feature allows the specifications to be changed “on-the-fly” without
slaying and restarting the app. Note: re-read feature is not available
prior to 6.3.30 or 6.4.0.
Notes:
This task is normally started in the go script that starts CyFlex.
fa_total is not a mass flow measurement application such as “lc_scales”,
“cf_scales”, or “scales”. The primary purpose of fa_total is to
continuously sum one or more fuel flow values with one or more air flow
values and calculate the following:
Total fuel rate (Fuel_rate)
Air-fuel equivalence ratio (lambda)
Total dry mass air flow rate (air_mtr0_mfd)
Total wet mass air flow rate (air_mtr0_mf)
Fuel-air equivalence ratio (phi)
Air-fuel ratio (AF_ratio)
All of the above variables are specified in perf_labels and will be updated
by fa_total at the rate specified when it is spawned. You cannot configure
which variables fa_total updates, it will always update the variables created
by perf_labels.
In order to calculate these values, the following variables are needed as inputs
to the program:
Power generated (Dyno_power)
Fuel mass flow variable(s)
Dry air mass flow variable(s)
Wet air mass flow variable(s)
The variable used for Dyno_power is specified in perf_labels. The fuel and air
mass flow variables are specified in the fa_specs spec file.
fa_total will also update the following variables during a fuel reading. These
variables are created by sys_start and specified in /cell/logi_specs:
FR_in_prg
FR_request
FR_runtime
The most common use for fa_total is when using a continuous fuel flow measurement
device such as a Flotron, Coriolis meter, or a positive displacement meter of some kind.
Use fa_total for a continuous fuel flow measurement device such as a Flotron or Coriolis meter, or a positive displacement meter of some kind.