Aerospace manufacturers must carefully test their jet engines’ high-speed rotation, since malfunctions could have catastrophic results. Many manufacturers opt to perform these essential evaluations via spin burst testing, which ensures the strength and reliability of spinning components in the face of centrifugal force.
NASA uses several different testing techniques, which engineers perform in special facilities due to the unique dangers posed by the rapidly spinning blades and other parts that these tests involve. Manufacturers can also implement a spin burst testing regime on operating engines, but these tests tend to cost more, and it’s more difficult to control variables and take measurements during them.
Testing facilities usually supply torque for spinning by operating small turbines using air or steam. Some facilities also use electric motors. For hot spin testing, engineers typically use radiation or induction heating.
Spin Burst Testing in Aerospace Turbine Assembly
As in any industry, aerospace manufacturers continually seek to build more efficient machines using lightweight materials, which helps propel growth in the field as a whole. Spin testing is an essential component of all new aerospace turbine projects.
There are many types of spin testing, including:
- Low cycle fatigue (LCF) spin testing and burst testing: The rotational speed repeatedly goes from low to high to see when components crack or fatigue
- Dynamic spin testing: Recreates lifelike conditions for the blade in terms of its geometry, manufacturing tolerances, material, attachment, and damping methods.
- Partial air spin testing: Introduces atmospheric conditions to create a more realistic testing environment
- Small spin test (high-speed spin testing): Essential for small elements that operate at higher RPMs.
Despite these variations, most spin testing methods follow the same basic pattern:
Testers suspend a rotor on a spindle in a vacuum chamber. The vacuum environment mitigates air friction, which otherwise prevents rotors from efficiently achieving high speeds and causes unsteady aerodynamic forces to destabilize the rotor. The equipment then spins the rotor via the spindle at high speeds using either compressed air or an electric motor, and engineers evaluate the spinning motion’s effects upon the rotor.
Spin Burst Testing Services and Applications
Implementing spin testing is crucial to preventing centrifugal burst disasters, and the FAA and other regulators require it for most aerospace components. It goes without saying that failures at the testing stage are must less costly that those that occur during flight.
Spin rig test facilities must be carefully designed to realistically evaluate spinning components, accurately record test results, and thoroughly protect testers from explosive forces.
When people think of spinning airplane components, they tend to think of propellers. However, there are many rotational parts on an aircraft (and on other machines), meaning that there are just as many applications for spin burst testing:
- Jet engine components
- Gears
- Compressor rotors
- Turbine rotors
- Centrifuge rotors
- HVAC fans
- Turbofans
- Impellers
- Metallic flywheels
- High-speed fans
- Turbochargers
- Composite flywheels
- High-speed machine tools
- Electric motor rotors
- Grinding wheels
The Ongoing Importance of Spin Burst Testing
Several companies offer spin burst testing services to help manufacturers ensure compliance with federal regulations and safety for pilots and passengers. As with the technology being tested, the testing process itself will continue to evolve in order to offer the most rigorous and realistic environments, helping determine the lifespan and reliability of rotating jet engine components in all aircraft coming off the production line.