Hello Professor,

Can you plese mention any specific industry, as your question is very vast. What you exactly want to do in terms of applying sensors.

good question

There are problems in application of sensors in industries with respect to their connections or coupling. For each industry, the problems or issues are different. Also the use of smart sensors and actuators for jet-engine control is currently limited by the availability of mature high-temperature electronic components that can withstand the engine operating environment. As this technology advances, smart devices will increasingly appear in engine applications.

One of the most challenging turbine-engine sensor requirements is measuring the gas temperature as it exits the combustor and enters the turbine. As engine temperatures have increased, the durability and performance limit of engine temperature sensors are an issue. Thermocouples are commonly used for engine temperature sensing, but their lifetime above 1100 ¹C (2000 ¹F) decreases rapidly. Since the first-stage turbine in advanced engines currently operates above this temperature, the temperature sensor has been moved downstream to a cooler environment. The turbine inlet temperature is then estimated using an empirically derived relationship.

However, this approach results in inaccuracies. For instance, it does not take engine-to-engine variations into account, nor does it compensate for engine operational changes due to normal "wear and tear." In addition, future-generation turbines are expected to have turbine inlet temperature well above 1650 ¹C (3000 ¹F), which renders the thermocouple approach unusable. On the latest advanced military engines, an optical pyrometer that measures turbine blade temperature is used to improve the accuracy of the turbine inlet temperature.

An improved temperature sensor that can provide accurate temperature measurement over a broad temperature range is under development. It uses an opaque coated sapphire rod to act as a near-black-body cavity. A fiber-optic guide collects the radiation emitted from the sapphire rod and transmits it to a photodetector. The resultant voltage is proportional to the engine temperature. This sensing technology will be an advancement, but it suffers from materials temperature limitations of the sapphire rod and silicon carbide housing that restrict the upper end of temperature measurement to about 1650 ¹C (3000 ¹F). Thus, although this technology offers an advancement beyond thermocouples and will probably be adequate for commercial jet engines for the foreseeable future, it does not represent the ''ultimate" solution.