Metrology to enable high temperature erosion testing

Erosion damage to power generation turbine blades costs 200 million euro per year in lost performance, outages, and repairs. This is caused by particles colliding at high speed and at high temperatures with the turbine’s blades, eroding their leading edges and reducing efficiency. The same effect occurs in aircraft engines where ingestion of dust, sand, and other particles can erode components. Concerns over the effects of ingesting volcanic dust particles grounded aircraft following the 2010 Icelandic eruption of Eyjafjallajökull, costing the airline industry an estimated 1.3 billion euro.

Innovative erosion-resistant materials could lead to in-service turbine efficiency improvements of up to 10 %. Testing these materials under representative conditions using high speed and high temperature particles is key to their successful development. However, few facilities exist that are able to conduct testing with the necessary precision and control. Replicating in-service conditions and reliably measuring erosion requires new and upgraded test facilities.

The EMRP project Metrology to enable high temperature erosion testing developed measurement capabilities for in situ measurements to improve existing facilities and underpin a new NMI-based high temperature solid particle erosion test facility capable of operating to 900 ^oC.

The project:

• Investigated parameters that affect erosion measurements such as volume, flow, speed, and temperature, enabling better matching of in-service conditions during testing.
• Characterised the shape and size of particles in erosion tests using measurement techniques such as optical microscopy and X-ray Computed Tomography, to ensure test conditions can be better matched to those experienced in-service
• Developed new imaging technology for accurately measuring particle speeds during testing using a laser and CCD camera.
• Incorporated developments into a new NMI facility which can reliably demonstrate the matching of test to in-service particle speeds, and incorporated in situ measurements enabling testing times to be reduced from five days to only a few hours.
• Developed and validated a predictive model for standard computers which simulates the effects of the vast numbers of individual particles used in erosion studies. This can rapidly and accurately relate test data to in-service component performance.

Engineers working to improve turbine efficiency, whether for power generation or aircraft fuel economy, require turbine material performance to be demonstrated through extensive testing. This project has enabled a step change in the capability for measuring erosion caused by high temperature particles, and for understanding and predicting the wear created. Project developments have been combined into a new facility that reduces erosion testing times by ~90 %.

Developers of innovative industrial materials that must demonstrate erosion resistance can now quickly identify optimal characteristics and gather accurate data on in situ performance. A UK company is using project knowledge to create more cost-effective erosion testing to validate their high temperature turbine coatings. Danish SME, Pyro Optic, successfully markets the particle speed measurement system to academia and industry. Improvements in predicting erosion material properties will deliver greater efficiency and durability to turbines, engines, and other components with engineered surfaces operating in harsh environments. This will save money, reduce emissions, and improve safety.