// PROPULSION SYSTEMS AND ENGINE TECHNOLOGY TERM
Film Cooling
Film cooling is a technique used to protect hot surfaces, like the inside of a rocket engine, from melting. It works by injecting a thin layer of cooler fluid along the surface, which acts as a protective barrier against extremely hot gases.
TECHNICAL DEFINITION
Film cooling is an active thermal management method in aerospace propulsion where a secondary coolant fluid is injected through slots or holes to form a thin, insulating boundary layer over a component's surface. This technique protects materials, such as combustion chamber liners and turbine blades, from direct contact with high-temperature combustion gases, mitigating heat flux and preventing thermal failure.
BACKGROUND
A turbine blade is a radial aerofoil mounted in the rim of a turbine disc and which produces a tangential force which rotates a turbine rotor. Each turbine disc has many blades. As such they are used in gas turbine engines and steam turbines. The blades are responsible for extracting energy from the high temperature, high pressure gas produced by the combustor. The turbine blades are often the limiting component of gas turbines. To survive in this difficult environment, turbine blades often use exotic materials like superalloys and many different methods of cooling that can be categorized as internal and external cooling, and thermal barrier coatings. Blade fatigue is a major source of failure in steam turbines and gas turbines. Fatigue is caused by the stress induced by vibration and resonance within the operating range of machinery. To protect blades from these high dynamic stresses, friction dampers are used.
READ MORE ON WIKIPEDIASYNONYMS & ALIASES
- boundary layer cooling
- surface injection cooling
- coolant film
- liner cooling
- wall cooling
- effusion cooling
USAGE NOTE
This technique is critical for increasing the operational temperature limits and lifespan of turbine blades and rocket combustion chambers.
DEVELOPERS
Organizations developing technology related to Film Cooling.
A leading producer of jet and turboprop engines, GE heavily invests in advanced materials and cooling technologies, including sophisticated film cooling designs for high-pressure turbine blades and nozzles to increase engine efficiency and thrust.
A subsidiary of RTX Corporation, Pratt & Whitney designs and manufactures aircraft engines for commercial and military applications. Their engines, like the F135 and the PW1000G Geared Turbofan, rely on advanced film cooling techniques to protect critical components from extreme temperatures.
A prominent multinational aerospace and defense company, Rolls-Royce develops complex cooling systems for its large civil and military gas turbine engines. They conduct extensive research on film cooling effectiveness and hole shaping to improve turbine durability and performance.
As one of NASA's primary centers for aeronautics and spaceflight propulsion research, the Glenn Research Center conducts fundamental and applied research on advanced cooling concepts, including experimental and computational studies of film cooling for next-generation jet engines and rocket components.
Now part of L3Harris Technologies, Aerojet Rocketdyne is a major American manufacturer of rocket and missile propulsion systems. They utilize film cooling in conjunction with other methods to protect rocket engine combustion chambers, injector faces, and nozzles from extreme combustion temperatures.
A French multinational aircraft engine manufacturer, Safran develops advanced technologies for its commercial and military engines. This includes innovating new film cooling schemes and manufacturing processes, often utilizing ceramic matrix composites (CMCs) which require tailored cooling solutions.
While a major player in industrial gas turbines for power generation, the core cooling technology is directly applicable and often co-developed with aerospace applications. Siemens Energy is a leader in developing advanced film cooling designs, hole geometries, and manufacturing techniques for turbine blades and vanes.
The primary scientific research and development center for the U.S. Air Force. The AFRL's Aerospace Systems Directorate spearheads research into next-generation propulsion, including advanced heat management and turbine cooling technologies like film cooling to enable higher turbine entry temperatures and improved engine performance.