Surface Engineering of Turbomachinery Components to Meet Future Industry Trends

Materials Engineer

Novel Solutions for Materials Engineering
Increased demands are being placed upon turbochargers as a result of ever more stringent emissions regulations, a necessity for improved product performance and reliability and a requirement for a wider product operating range. Consequently, a greater level of stress is placed upon the materials from which turbochargers are manufactured. In order to achieve all of the necessary legislation and customer requirements, novel solutions to materials engineering challenges are being developed.

Two such challenges faced by the turbocharger industry are high temperature tribology and the corrosion and erosion environment generated by long route exhaust gas recirculation (LR EGR). Cummins Turbo Technologies has developed innovative materials engineering solutions using surface treatments applied to cost effective substrates, rather than utilising much more expensive, exotic alloys.

High Temperature Tribology
As a consequence of experiencing excessive vane and slot wear whilst in service and experiencing temperatures > 500 °C, a thermochemical diffusion surface engineering solution was developed for variable geometry systems.

Figure 1 - Variable Geometry System

surface_1.jpg

Such technology was generated using a systematic approach to tribological testing and analysis, which was pioneered by Cummins Turbo Technologies as shown in Figure 2. After comprehensive evaluation of the problem using the expertise at Cummins Turbo Technologies, it was determined that during particular operating conditions the conventional uncoated nozzle and shroud plate experienced high levels of abrasive wear and elevated friction forces.

Figure 2 - Cummins Turbo Technologies Approach to Tribological Testing and Analysis

Figure2_Tribilogical_Testing_0.gifIn order to solve the problem, a multi-disciplinary cross functional team at Cummins Turbo Technologies used the relevant customer and regulatory requirements to identify and develop the surface treatment concept. Using cutting-edge techniques, the fundamental mechanical and physical properties of the thermochemical diffusion treatment were determined. Subsequently, the surface treatment was characterised in terms of friction and wear performance using a tribometer, which simulated the variable geometry nozzle to shroud plate interface and associated operating conditions.

The surface treatment was tested on a turbocharger, on both gas stand and engine, with the results correlated to tribometer-based testing to ensure consistency of performance. This approach to the problem ensured that a robust engineering solution was identified and implemented into production; the resultant positive impact on nozzle vane wear performance can be observed in Figure 3.

Figure 3 - Comparison of Wear Performance between Untreated and Surface Treated Nozzle Vanes

Figure3_Untreated_nozzle_vain_0_0.jpg

Abrasive Wear

Large Wear Volume

Figure3_Surface_Treated_nozzle_vain_0_0.jpg 

Abrasive Wear

Wear Volume

Significantly Decreased

Long Route Exhaust Gas Recirculation
The turbocharger compressor stage, which includes the compressor wheel and cover (Figure 4), is subjected to a corrosive and erosive environment when an engine is operating LR EGR. The chemistry and pH of the condensate present in the compressor stage varies depending on engine operating conditions and the chemistry of the fuel. Furthermore, the architecture of the LR EGR system dictates the density and size of erosive particles to which the compressor stage is subjected.

Figure 4 - Compressor Wheel and Compressor Cover

Figure4_Compressor_Wheel.jpgFigure4_Compressor_Cover.jpg

In order to minimise the wear and corrosion observed on the compressor wheel and cover as a result of interaction with condensate and erosive particles, surface treatments were developed for the two components. Numerous concepts for both components were identified using a multi-disciplinary cross functional team at Cummins Turbo Technologies, using regulatory and customer requirements as a guideline.

Subsequently, the concepts were subjected to numerous in-house tests which were developed using the expertise of Cummins Turbo Technologies:

Mechanical properties
Aerodynamic performance
Corrosion resistance
Erosion performance

Such experiments utilised surface treated test bars and also components in order to correlate the data from fundamental laboratory to turbocharger-based testing. The acquired data was analysed using the expertise of Cummins Turbo Technologies and various advanced techniques, with the results input into a comprehensive scoring matrix in order to select the most appropriate solution for the two respective components.

The process developed for the compressor wheel was of an anodising type, whereas a polymeric coating was developed for the compressor cover. As a result of the research and development work conducted, these technologies have been proven to significantly reduce the wear and corrosion observed on compressor wheels and covers subjected to LR EGR environments. A comparison of untreated and surface treated compressor wheels and covers can be observed in Figure 5.

Figure 5 - Untreated and Treated Compressor Wheels and Covers

compressorwheel.jpg

compressor1.jpg

Untreated at Top

Treat at Bottom

Experts at Cummins Turbo Technologies are continually developing novel solutions to materials engineering challenges in order to meet customer requirements for more robust and durable products.

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Cummins Inc.

Cummins is a global power leader that designs, manufactures, sells and services diesel and alternative fuel engines from 2.8 to 95 liters, diesel and alternative-fueled electrical generator sets from 2.5 to 3,500 kW, as well as related components and technology. Cummins serves its customers through its network of 600 company-owned and independent distributor facilities and more than 7,200 dealer locations in over 190 countries and territories.

It’s time for the next generation in HE300 Variable Geometry Turbocharger technology

Holset® turbochargers are synonymous with turbomachinery and air handling excellence across the globe. Engineered and manufactured by Cummins Turbo Technologies (CTT), Holset turbochargers have set the standard for turbocharger technology and design in the mid-range and heavy-duty diesel engine market for more than six decades.

The latest Series 300 Variable Geometry Turbocharger (VGT), which launches in 2024, will deliver performance enhancements as well as significant efficiency and reliability upgrades to the current HE300VG turbocharger.

Designed for diesel engines ranging from six to nine liters for the on- and off-highway commercial vehicle market, the 300 Series VGT is typically found on mid-range engine applications like trucks (pick-up/cab chassis), buses, front-end loaders and excavators. The 300 Series VGT, along with other critical elements found on a diesel powertrain, will likely play a critical role in helping customers’ meet future emission standards in Europe and the U.S. 

VGT Mechanism

The upcoming HE300 VGT offers further enhancements by introducing a new compressor and turbine stage to achieve higher turbocharger efficiency compared to its predecessor. This was possible with CTT’s latest and best practice wheel design. It also features a new rotor system which provides a more stable rotor platform that can support new aero enhancements. A new free-rotating multi-clearance shroud provides significant performance gains - specifically at lower flows that add value through improved engine down speeding and fuel economy.

Always at the forefront of technology, Cummins’ Holset brand continually develops innovative solutions to deliver reliable turbochargers that offer best-in-class performance and exceed customers’ expectations. “CTT’s variable geometry turbo architecture will offer improved performance while maintaining reliability and durability,” said Arun Ramachandran, General Manager – America. "Its advanced design helps achieve improved fuel economy and meet emission regulations without compromising performance, which is critical to ensuring our customers continue to be competitive in the mid-range market.”  

Stay connected with Cummins and learn more about the exciting developments we’re making to the 300 VGT by signing up for our newsletter. Subscribe below! 

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Cummins Inc.

Cummins is a global power leader that designs, manufactures, sells and services diesel and alternative fuel engines from 2.8 to 95 liters, diesel and alternative-fueled electrical generator sets from 2.5 to 3,500 kW, as well as related components and technology. Cummins serves its customers through its network of 600 company-owned and independent distributor facilities and more than 7,200 dealer locations in over 190 countries and territories.

Cummins introduces the Advanced Series 150 Holset Wastegate (WG) Turbocharger

Cummins introduces the Advanced Series 150 Holset Wastegate (WG) Turbocharger

For more than 60 years, Cummins has been powering their customers’ success with class leading air handling technologies. That legacy continues with the introduction of the next generation Series 150 Holset Wastegate (WG) turbocharger from Cummins Turbo Technologies (CTT). 

Engineered by Cummins Turbo Technologies and manufactured in Wuxi, China, the advanced Series 150 turbocharger will initially be available to the light-duty truck market in China in the second quarter of 2021.

Featuring the latest wastegate technology, the Series 150 caters to typical truck applications for the on-highway light-duty commercial vehicle market with engines ranging from 2.8L to 3.8L. This turbocharger has a standard pneumatic wastegate mechanism and can be easily integrated with electric wastegates.

The new turbocharger better supports low end torque requirements and offers improved fuel economy benefits at duty cycle zones for typical 4.5-6 Ton gross vehicle weight (GVW) applications.

The Series 150 turbocharger has achieved improved performance versus its predecessor and offers the following technological advancements:

  • Improved next generation turbine wheel design to provide superior performance.
  • Improved low end torque, which can support 350-380Nm at 1000rpm.
  • Higher turbo efficiency up to ~2% points at duty cycle.
  • Non-Map width enhanced compressor stage, which provides higher low flow performance and can meet engine altitude flow criteria.
  • The capability to integrate with an electronic wastegate actuator. 
  • The ability to work with exhaust throttle valve (ETV) architecture.

“In addition to improved turbo efficiency and fuel economy, these advancements also offer improved drivability, better altitude margin and can help in meeting more stringent emission regulations,” said Brett W Fathauer, Executive Director - Research & Engineering at Cummins Turbo Technologies. “We believe the pneumatic wastegate design found in the Series 150 will cater to light-duty commercial vehicle customers in India and China where compact turbochargers are becoming increasingly desirable and useful in powering our customers’ success.”

The Series 150 light-duty turbocharger offered by Cummins is the latest product development that will expand on the Company’s current market-leading position in the design and manufacture of turbochargers for the commercial diesel engine market.

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Cummins Inc.

Cummins is a global power leader that designs, manufactures, sells and services diesel and alternative fuel engines from 2.8 to 95 liters, diesel and alternative-fueled electrical generator sets from 2.5 to 3,500 kW, as well as related components and technology. Cummins serves its customers through its network of 600 company-owned and independent distributor facilities and more than 7,200 dealer locations in over 190 countries and territories.

Cummins introduces new compressor stage to Series 800 Holset Turbocharger

Cummins Holset Turbo HE800

Cummins Turbo Technologies (CTT) offers advanced improvements to the Series 800 Holset Turbocharger with an all-new compressor stage. The Series 800 Holset Turbocharger from CTT offers a world class product for its global customers that focuses on delivering performance and uptime in high-horsepower industrial markets.

Already a key component of CTT’s product catalogue, the Series 800 Turbocharger takes a leap forward and has been revitalized to deliver significant improvements in performance, flow range, temperature capability and seal robustness. The Series 800 turbocharger is designed for engines ranging from15L to 28L, but can be paired with two or four additional turbochargers for engines ranging from 28L up to 100L.

The Series 800 turbocharger has achieved its best-in-class results by introducing technological advancements like:

  • High Pressure Ratio Compressor 
  • Extended flow range 
  • Thin wall stainless steel compressor cover
  • Lead free bearings option
  • High temperature capable turbine housing option 
  • Improved seal and joint robustness

For the very first time we are introducing the High-Pressure Ratio Compressor (HPRC) technology on Series 800 Turbocharger. This product architecture increases flow range capability by up to 25% and is optimized for pressure ratios of up to 6.5:1. These capabilities have allowed our customers to uprate engines by 20-40% without the need to move to a 2-stage architecture. We have also enabled additional altitude capability for many applications. The HPRC offering also improves our product efficiency. These gains enable air handling architectures which have resulted in 5-7% BSFC improvements for existing applications during engine simulation work. 

The new Series 800 Holset Turbocharger is available with a thin walled stainless-steel compressor cover, enabling us to increase capability without adding to our weight or space claim. We also offer lead free bearings, high temperature capable turbine housings and have increased robustness of our joints and seals.

At Cummins, our continued investment in research and development enables us to engineer new solutions for this market. We are currently in development of an integrated electronic wastegate for optimal flow control as well as focusing on turbine stage efficiency improvement.  

“We are excited to be offering new innovative technologies to increase the capability of the HE800 product line without needing additional space claim. We have been able to leverage our technical engineering expertise and advanced simulation analysis to provide critical air-handling features such as higher-pressure ratios and improved efficiencies while offering more product robustness.” commented Brett Fathauer, Executive Director – Engineering and Research. 
The performance results of the upgraded Series 800 Turbocharger have been met with enthusiasm from off-highway customers who describe the Holset product as "class leading.”

The team at CTT has used the latest design practices to ensure this new product is superior to competition and drives value for customers. The upgraded Series 800 Turbocharger is available now and caters to a wide range of off-highway customer applications including power generation, agricultural, mining, oil & gas, rail, construction and marine. 

"At CTT, we continuously work to improve our products for on- and off-highway customers. The new Series 800 turbo is a class-leading product which exceeds performance expectations and provides excellent value for our customers around the globe," commented Matt Franklin, Director - Product Management and Marketing at Cummins Turbo Technologies.

Learn more and stay up to date on our latest advancements by signing up for our quarterly newsletter and email updates
 

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Cummins Inc.

Cummins is a global power leader that designs, manufactures, sells and services diesel and alternative fuel engines from 2.8 to 95 liters, diesel and alternative-fueled electrical generator sets from 2.5 to 3,500 kW, as well as related components and technology. Cummins serves its customers through its network of 600 company-owned and independent distributor facilities and more than 7,200 dealer locations in over 190 countries and territories.

Turbocharger innovation: small changes that make a powerful difference

Oil leakage of a turbocharger is a failure mode which can lead to reductions in performance, oil consumption, and emission non-compliance. Cummins' latest oil sealing innovation reduces these risks through the development of a more robust sealing system which compliments other leading innovations developed for Holset® turbochargers.  

The redefining oil sealing technology from Cummins Turbo Technologies (CTT) celebrates nine months of being available to market. The revolutionary technology, currently undergoing international patent application, is suitable for applications across on-highway and off-highway markets.

Unveiled in September 2019 at the 24th Supercharging Conference in Dresden in the whitepaper, "Development of an Improved Turbocharger Dynamic Seal," the technology was developed through Cummins research and development (R&D) and was pioneered by Matthew Purdey, group leader in Subsystems Engineering at CTT. 

The research came in response to customers demanding smaller engines with greater power density, along with lower emissions, and the turbocharger remained one of the most critical components on a vehicle driveline. Due to this, Cummins has continuously remained dedicated to delivering excellence to customers through continually exploring innovative ways to improve turbocharger performance and by considering improvements which affect durability, as well as performance and emission benefits. This new technology further enhances the oil sealing capability to offer a wide range of benefits to customers.

What are the benefits of the new oil sealing technology?

The new sealing technology for Holset® turbochargers allows turbo down speeding, downsizing, oil leakage prevention on two-stage systems and enables CO2 and NOx reductions for other technologies. The technology has also improved thermal management and reliability of the turbocharger. In addition, due to its robustness, it has positively affected the frequency of maintenance of a diesel engine. 

Other key elements were also taken into consideration when the sealing technology was in the research and development stages. These include allowing for optimisation of the compressor stage diffuser and a drive for closer integration between the aftertreatment and turbocharger, an integration which has already been subject to significant R&D from Cummins and forms a significant part of the Integrated System concept.

What experience does Cummins have with this type of research?

Cummins has more than 60 years of experience developing Holset turbochargers and uses in-house testing facilities to conduct stringent testing and repetitive analysis on new products and technologies. 

“Multi-phase Computational Fluid Dynamics (CFD) was used to model the oil behavior in the seal system. This led to a much deeper understanding of the oil/gas interaction and physics at play. This deeper understanding influenced design improvements to deliver the new sealing technology with unmatched performance,” said Matt Franklin, Director – Product Management & Marketing. 

Due to this rigorous testing regimen, the final product exceeded the seal capability by five times the projects initial target. 

What further research should customers expect to see from Cummins Turbo Technologies?

The continued investment in research and development for diesel turbo technologies is ongoing and demonstrates Cummins’ commitment to delivering industry leading diesel solutions across the on-highway and off-highway market.  

For further information about Holset technology improvements, join the Cummins Turbo Technologies quarterly newsletter. 

Cummins Turbo Technologies News

Stay up to speed on the latest turbocharger technology by signing up for the Cummins Turbo Technologies quarterly newsletter.

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Cummins Inc.

Cummins is a global power leader that designs, manufactures, sells and services diesel and alternative fuel engines from 2.8 to 95 liters, diesel and alternative-fueled electrical generator sets from 2.5 to 3,500 kW, as well as related components and technology. Cummins serves its customers through its network of 600 company-owned and independent distributor facilities and more than 7,200 dealer locations in over 190 countries and territories.

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