High temperature measurements in the context of aerospace turbines

High temperature sensors enable turbine measurements. Our sensors can go significantly above 1000 degrees F, making dynamic strain and pressure measurements a reality for optimizing combustion heat engines.

In discussions with an engineer who works with the aerospace industry, I was asked about high temperature measurement parameters that would benefit the optimization of gas turbines… Questions that lead to deeper questions.

In this turbine application there are many measurements that are currently nonexistent because of the temperature. That is a lot of room to find opportunity. You have a need to optimize mass and this nearly always creates physical compromises with vibration, high cycle fatigue, and aeroelastic vibration. Mass optimization and dynamics are delicate tango. In your system I would suggest the following as a few starting points:

– Injector performance including high frequency monitoring of injector strain. Injector dynamics is a key part of the isobaric section. It can be a silent killer of combustion efficiency. Injector fuel flow oscillations are usually unknown as well as the dynamic pressure in the combustion chamber. Static pressure (the average operating point) is known from taps / less exotic sensors. Oscillating pressure is unknown and significant. Combustion dynamic pressure cannot be measured effectively by pressure taps because the tap lines act as a low pass filter. Thus a high temperature chamber wall strain measurement or direct pressure measurement may be advantageous.
– Combustion chamber dynamic pressure vs torsional natural frequency on the rotor. Torsional vibration on the rotor can be excited by with combustion dynamic pressure and create high fatigue conditions. Avoiding torsional natural frequencies by design is difficult especially when dynamic combustion pressure is unmeasured & poorly estimated. Design optimization for torsional natural frequencies vs combustion dynamics can reduce weight and improve fatigue life.
– Material creep.
– Laval nozzle or thrust direction component strain & optimization. Measuring dynamic strain / dynamic hoop strain in the exhaust nozzle for optimizing flow with the objective of tuning the shape for minimal mechanical impedance to flow. Again this relates to dynamic pressure since these engines are not static organisms. This is a relatively untapped area of research that would allow confirmation or tuning of CFD and flow models. It impacts design optimization upstream in the compressor too.

The goal with the torsional rotor vibration vs dynamic combustion pressure is directly applicable to mass reduction of the rotor and possibly combustion chamber components.

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