Filtered Rayleigh Scattering Approach for Multi-Property Flow Measurement in Tactical Aircraft Inlets

The development of new military aircraft with improved stealth, lower ground noise and higher efficiency engine designs is driving increasingly complex inlet geometries. The momentum created by a gas turbine engine is highly dependent on the characteristics of the incoming airflow, necessitating accurate understanding of inlet flow distortion characteristics to ensure proper operation over the entire operational envelope. As such, design engineers must account for possible distortions to that inlet flow when designing and testing prototype aircraft. To assist with current and future engine/aircraft design and development, new distortion characterization technologies are required. Although characterization of the inlet flow properties can be done during development, these techniques are often invasive. Common techniques for characterization use pitot tubes that can perturb the flow. Furthermore, damage to sensors that protrude into the flow can result in expensive domestic object damage events. More critically, the operability of the engine can be influenced by thermal, pressure, or swirl distortion. Certain combinations of angle of attack and flight speed can lead to surge conditions, potentially causing expensive damage to engines. Prime Photonics proposes to work with the TurboLab of Virginia Tech to develop a robust, minimally invasive, flight-ready inlet distortion characterization system.