Sensing of isolator shock systems

A method for an engine system, the method comprising:

• obtaining, by a processor, sensor values from one or more of a plurality of strain sensors distributed axially along a radially outward surface of an isolator duct that extends axially from an inlet side and a burner side, wherein the sensor values are strain data sensed by the plurality of strain sensors on the radially outward surface of the isolator duct;
• determining, by the processor, a measured strain distribution based on the sensor values and axial locations of the plurality of strain sensors;
• estimating, by the processor, a shock train leading edge position of a shock train based on identifying a shock train leading edge in the measured strain distribution, wherein the engine system comprises an air-breathing propulsion engine;
• and
• controlling, based on the estimated shock train leading edge position, at least one of a fuel injector to modulate fuel flow to the engine system and control back pressure produced by the engine system to at least prevent an unstart from occurring in the engine system and one or more bleed valves to at least one of divert low-momentum boundary layer air to prevent premature unstart or bypass air to reduce combustion backpressure or a combination thereof.