Solid-State Viscosity Sensors For Military and Aerospace Applications

Acoustic wave sensors provide advantages over conventional mechanical and electro-mechanical viscometers.

Embedded OEM application markets such as the military and aerospace industries are experiencing a growing demand for sensors that provide instantaneous and continuous process control and machine health information. For a large segment of these industries, fluid viscosity is the key physical parameter that can assist in final process control and machine diagnostics. To that end, it is imperative that a solid-state chip be cost-effective and provide the functionality and scalability that is demanded.

The requirements placed on equipment readiness and safety have placed greater emphasis on onboard knowledge of lubricant condition and capability to prognosticate failure. Knowledge of viscosity in real time provides a significant benefit to measure the condition of oil during commercial operations and prevent incipient mechanical failure. Solid-state viscometers based on acoustic wave sensor technology are now available that allow for integration into inline, real-time viscosity oil condition monitoring in embedded mobile and fixed asset applications.

Contaminants in oil (water, solvents, and fuel) and constant temperature cycling are known to degrade viscosity, which in turn can cause damage to internal components of diesel assets, whether they are construction equipment or military Hummers. High water contamination levels in diesel fuel have been shown to cause corrosion and pitting, leading to increased metal wear particle counts. The presence of residual cleaning solvents and fuel contamination has caused seals to swell and create less than ideal engine operating situations. In fixed assets such as gearboxes and power generation sets, the challenging environment of plant operation over the course of time reduces the hydrodynamic lubricity of the oil due to the reduction of additives and detergents in the oil.