01 / READ THE CHANGE
Two characteristics meet
The compressor pressure rise and downstream resistance must agree at the operating flow. Moving either curve moves their intersection.
FIND THE INTERSECTION.
Compressor Map & Operating Limits
Move the corrected-speed line and the throttle characteristic. Locate the operating point and distinguish a map boundary from a surge prediction.
INTERACTIVE CALCULATED DIAGRAMB · LIVE
Diagram · drag background to pan
Drag the turquoise handles, or focus a handle and use arrow keys. The sliders provide the same controls.
Preparing the calculation…
A · no saved reference
02 / READ THE CHANGE
Correct the inlet condition
Corrected mass flow and corrected speed remove a reference pressure/temperature scaling. Actual mass flow still changes with inlet conditions.
03 / READ THE CHANGE
Do not confuse two instabilities
Rotating stall concerns local blade-row flow. Surge involves the whole compression system and storage/inertance. This steady synthetic map predicts neither waveform.
THE SAME MODEL, CONNECTED VIEWS
Follow the calculation
B · solid turquoise A · dashed amber
Compare A and B
| Quantity | A · saved | B · live | B − A | Unit |
|---|
A remains fixed until saved again. Export includes the model version, settings and plotted data.
Equations, assumptions & sources
Read the balance, then connect each symbol to the model. Open a symbol key for definitions and units. Long equations can be scrolled sideways.
01 · A synthetic speed line
This illustrative curve teaches map interpretation; it is not a measured compressor map.
Symbols & units
- Normalised corrected speed: selected corrected-speed percentage divided by 100.
- Normalised corrected flow: corrected mass flow divided by 20 kg/s.
- Dimensionless compressor total-pressure ratio.
02 · Find the throttle intersection
The operating point is where the throttle curve intersects the selected speed line.
Symbols & units
- Dimensionless throttle resistance in this synthetic map.
03 · Convert corrected flow to actual flow
Corrected flow removes the stated inlet pressure and temperature scaling.
Symbols & units
- Mass-flow rates, kg/s.
- Inlet total and reference absolute pressures, in the same units; reference 101.325 kPa.
- Inlet total and reference temperatures, K; reference 288.15 K.
Synthetic map, reference flow 20 kg/s, reference pressure 101.325 kPa and temperature 288.15 K. Boundary q = 0.7n is an illustrative stability boundary, not manufacturer surge data. Reported margin is horizontal flow-distance / operating flow, not a certified surge-margin convention. Inlet temperature/pressure change actual flow, not the selected corrected-speed line.
SFTE · gas turbine propulsion ↗Physical relations and teaching sources support the stated concepts. Generic coefficients are explicitly illustrative; they are not measured manufacturer data. Numerical verification is separate from experimental validation. Model version: applied-labs-v1.1.