Diversifying Supply Chain to Prevent Dependency:
Emily DeSimone, SLM Solutions
In an unfortunate time in our history, a vulnerability in supply chains has been exposed and it has awakened many companies to re-evaluate: is this working for us? Often not.
Will 3D printing replace conventional manufacturing? Not so, but an aggressive supplement to traditional manufacturing.
SLM Solutions started using its own machines to fabricate spare parts for itself after coronavirus shutdowns in China led to global shortages. While 3D printing can often be more costly than traditional processes, it takes much less time to get a 3D printer up and running with a new design than it does to ramp up a fresh factory line.
Companies can remain agile and have a digital inventory of spare parts rather than millions of dollars of capital tied up in warehouses. We are now at the point where you can monitor your customer base regionally and map digital files to parts that require lifetime warranty to service.
Additive manufacturing will make manufacturing more distributed. Once you have the machine rather locating it in low-cost production country, it can be placed anywhere nearby the point of consumption.
Shortened lead times = Fastest to market
You can begin to focus on the performance and functionality of the component by leveraging topology optimization or consolidation of parts. When a company is prioritizing a holy grail of part(s) that with 3D printing that can achieve better performance and improved functionality, we will always be able to justify the economics.
I challenge you to make the end-use final part on the same platform in which you designed it, prototype to manufacture on the same platform.
Characteristic Analysis of Intrinsic Excitation Source for Combustion Instabilities in Model Swirl Combustor:
Ding Yang, Huadian Electric Power Research Institute Co. Ltd
The factors that cause combustion instabilities in the combustion chamber are very complicated. Identifying the excitation source that may cause combustion instabilities in the combustor can provide a basis for suppressing combustion instability. The characteristics of intrinsic excitation source for the combustion instabilities of the model swirl combustor are analyzed, and the main excitation factors are decomposed from the pressure fluctuation signal and then verified.
First, Empirical Mode Decomposition (EMD) is used to decompose the original signal into a series of Intrinsic Mode Functions (IMFs) with different time characteristic scales, and then Fast Fourier Transform (FFT) is performed on each IMF to obtain their corresponding dominant frequencies.
Finally, compared with the pressure signal under cold conditions with the same parameters, the CH* pulsation signal under the combustion state and the flame front oscillation signal spectrum of the high-speed CCD image, it is found that the main IMFs have important physical meanings.
Research has shown that from the combustion chamber pressure pulsation signal, the characteristics of the excitation source such as the swirl pulsation of the intake air, the pulsation of the heat release rate and the periodic change of the flame surface can be identified. Thus, the excitation source leading to combustion instabilities is found, which provides a basis for restraining combustion instabilities.
Design, Development, Testing and Validation of and Improved Lower Emission Additively Manufactured Combustor Pilot Nozzle for F Class Industrial Gas Turbine:
Gregory Vogel, PSM
Emerging additive manufacturing technology offers many opportunities for improved design in gas turbine components by enabling optimization of parts that are not manufacturable with conventional methods. The combustion components, for example, require complex fuel and air circuits to achieve best possible mixing and oxidation process for the lowest emissions possible. Thanks to the additive manufacturing, new combustor parts are making a break thru for improved capabilities in fuel flexibility and operating conditions. Also, quick turn around and modularity makes additive manufacturing a key enabler for fast validation of design concepts.
This technical presentation will describe the application of additive manufacturing technology in an F class industrial gas turbine including design, development and validation steps of a combustor pilot nozzle. A systematic design approach was undertaken to examine all aspects of combustion operation and testing, down-selecting the appropriate design, material and to productionize. Experiences gained from other AM production parts as well as testing coupons were leveraged to ensure a robust production process. Combustion atmospheric rig testing was conducted to validate emissions performance. Detailed thermal and structure analysis were performed and validated with testing experience.
The new design demonstrated a benefit in reducing by half the emissions in start-up emissions as well as improved combustion stability. In addition to the operability benefits, about 1/3rd reduction in cost of the production assembly was realized. A main cost advantage gained with the utilization of additive manufacturing was the reduction in part quantity from 7 individual components down to 1. Constraints typical of conventional manufacturing methods were avoided with the implementation of innovative geometries only achievable by additive manufacturing. In addition to combustor component reduction, the additive process was also leveraged to reduce the total number of fuel circuits in the combustion system, making the installation and control logic more straightforward.
Several sets were successfully installed in customer's engines, benefiting from an improved combustor pilot nozzle. Detail of the design and development steps as well as the results of combustion tests will be presented and discussed. It shows that with proper considerations of the additive manufacturing technology, very quick turn-around of improved combustions solutions implementation can be achieved: less than a year from development to production!
Design and Manufacturing of Micro-Turbine Recuperators With Advanced Additive-Manufacturing Techniques for Aerospace and Power Generation Applications:
James Zess, MCHX Technology
Gas turbine companies continue to focus on designing engines with reduced levels of fuel burn per unit power. With the operational demands in the rapidly growing general aviation, high-altitude drones, range extenders for hybrid-electric vehicles, and renewable energy sectors, it is recognized that high power density microturbines have many advantages, including fuel efficiency, fuel flexibility, low noise, low emissions, low maintenance, lightweight, and high reliability over other power plants. One way to increase the efficiency of a conventional gas turbine Brayton cycle, especially in microturbines, is by recovering the engine exhaust gas waste heat before it is released to the environment. A heat exchanger, also known as a recuperator, recovers heat from the engine exhaust gas to increase the temperature of the compressed air before combustion. As such, the amount of fuel that is required to reach the final combustion temperature is reduced. Thermodynamic cycle efficiency, and therefore fuel consumption, is directly proportional to the thermal effectiveness and pressure drop of the flow across the recuperator.
Despite many attempts, the recuperated cycle concept capable of meeting the size and weight limitations, aerothermal performance, endurance, and reliability has never been successfully implemented in aviation gas turbines. The challenging criteria needed to be met in the recuperator design for microturbines are largely the minimal pressure drop and maximum heat transfer effectiveness across the air and exhaust streams with minimal weight and size. Other challenges include structural integrity and flow leakage due to external forces imposed by severe flight maneuvers, and engine layout. In addition, improper positioning of the recuperator in a gas turbine could reduce the expansion ratio of the last turbine stage, hence limiting the turbine work coefficient and negatively impacting the engine performance. Higher recuperator thermal effectiveness either requires more exchange surfaces, resulting in a larger recuperator size, or higher heat transfer coefficients, which may result in a higher pressure drop. In general, microturbine recuperators are required to be compact and lightweight, highly effective in transferring heat with low-pressure fluid pressure drop and be manufactured at reasonable costs.
To that end, MCHX Technology has developed an ultra-compact micro-channel heat exchanger to provide highly effective heat transfer for a high thermal efficiency microturbine that is designed by Turbine Aeronautics. MCHX recuperators consist of assemblies of thin plates of high-temperature materials, such as stainless steel and Nickel-based alloys for stationary power generation, or lightweight Titanium and ceramics for aviation and transportation applications. The microchannel structures have been traditionally chemically etched or machined into each plate. These traditional chemical and mechanical manufacturing methods were considered for this design, but they are difficult and costly as a large percentage of the expensive alloy is lost during manufacturing. Fraunhofer Institute for Manufacturing Technology and Advanced Materials (IFAM) has recently developed a three-dimensional metal screen printing fabrication process that is very well suited for large volume production of flat metallic or ceramic parts with high aspect ratio structures. This additive manufacturing technique has been applied to the MCHX recuperator plates to print geometrical accurate microchannels and provide significant saving in manufacturing costs.
This paper will first present the thermodynamic goals and layout limitations for compactness and weight in microturbines, with an emphasis on an aviation and a land-based microturbine. The recuperator design for traditional manufacturing methods differs from those designed for additive manufacturing. The IFAM manufacturing technique, that differs from the widely-known direct metal laser sintering (DMLS) will be explained. Practical limitations of the DMLS in microchannel recuperator manufacturing such as porosity, structural integrity, and fatigue life, especially in the context of gas turbines, will be discussed. The MCHX material selection and design with the IFAM additive manufacturing technique will be presented after that. In addition to the topics of de-binding, sintering and diffusion bonding, all being carried out in one operation, the effectiveness and pressure drop results will also be discussed in the full paper.
Long Term Exposure and Evaluation of Am Haynes 188:
Vamadevan Gowreesan, Sulzer
Additive Manufacturing opens opportunities to fabricate various replacement parts for turbo machinery repair. However, the response of the material to heat treatment and long-term thermal exposure may not be same as that of a conventionally processed wrought or cast component, of the nominally same alloy. Lack of such data for specific alloys could prevent us from fully utilizing the potential of additive manufacturing for the fabrication of high-performance turbo machinery components.
Haynes 188 is a Cobalt based superalloy commonly used in hot section of gas turbines. However only limited information is available in the literature on additively made Haynes 188. To address this, Sulzer performed an internal study on additively manufactured Haynes 188. This presentation discusses the results of the study.
The study consisted of three main tasks. The first task was to evaluate the response to heat treatment of AM Haynes 188 and to determine the optimized heat treatment. The second task was to generate mechanical properties of the optimally heat-treated samples. The third task was to subject some optimally heat-treated Haynes 188 AM coupons to long thermal exposure and then to evaluate them. The evaluation included testing of mechanical properties and metallurgical changes due to the long-term exposure. In addition, the response to the long-term exposure of conventional, wrought Haynes 188, was evaluated and compared with that of the AM coupons.
Analysis of Environmental Conditions in the Operation of a Gas Turbine:
Sayuri Chávez, COES
In Peru there are various types of electricity generation, hydroelectric, thermoelectric and renewable generation, in 2018 the participation of thermoelectric generation occupied 37.82%, in 2019 it occupies 38.41%, it is observed in this way that by increasing the Electricity demand in Peru increases the share of thermoelectric plants. There are different types of technology in the production of thermoelectric generation, such as combined cycle, gas turbines, steam and diesel turbines, with gas turbines occupying, either in their combined cycle or simple cycle mode, a participation of 98.07 %.
Even when an increase in renewable generation is observed, gas turbines will continue to play an important role in electricity generation in Peru because they ensure operation during times of maximum demand. This is why various studies have been carried out around the world on the operation of gas turbines, where some of the main factors that determine their behavior are environmental conditions.
The operation of gas turbines depends on the environmental conditions in which it is operating. The purpose of this work is to study the impact of environmental conditions on effective power and performance in a gas turbine operating in a simple cycle of the SEIN (National Interconnected Electric System) and compare the results obtained with the behavior curves of a gas turbine operating in a simple cycle, provided by the manufacturer.
Modelling Techniques for Selective Laser Melting Technology:
Grzegorz Moneta, Lukasiewicz Research Network – Institute of Aviation
Selective Laser Melting (SLM) is driven by the need to manufacture multi-functional and complex components with high structural integrity and extended lifetime.
Because of the large energy density of the laser beam, problems like balling, high residual stresses and deformation occur. Elements processed by SLM often present imperfections which influence key properties, such as tensile yield strength, elongation, strain-to-failure, etc. Laser power, scan speed, hatch spacing, layer thickness, scanning strategy, powder material properties and chamber environment are the key SLM parameters, which can be the cause of defects such as keyholes, pores, lack of fusion holes, and cracks, in case they are improperly chosen or involuntary affected during the process.
In the turbomachinery industry, SLM is receiving more and more interest to produce complex, multi-functional and lightweight parts. The inherent presence of defects in SLM components has a significant impact on their reliability, durability and performance. Understanding of behaviour and ability to predict the state of SLM parts plays a key role in implementation of this manufacturing technology.
The presented work shows practical cases of numerical modelling and prediction of key challenges highlighted above: distortions, porosity, microstructure properties and residual stress distributions. Having validated models, the simulations can be iteratively repeated to determine optimum parameters, which will improve performance and fatigue life of parts. Additionally, development of manufacturing strategy, process parameters and numerical models can be aided by Artificial Intelligence to further reduce time and cost of implementation of SLM technology.
Static Load Characteristics of Additively Manufactured Hybrid Thrust Bearings: Measurements Versus Predictions:
Keun Ryu, Hanyang University
Process fluid turbomachinery implements hybrid fluid film thrust bearings, combination of hydrostatic and hydrodynamic to support axial load and control axial shaft motions. Hybrid fluid film bearings offer significantly enhanced durability with very low friction and wear while providing accurate rotor positioning as well as large load and static stiffness characteristics even working with low viscosity liquids.
Additive manufacturing allows cost-effective and time-saving fabrication for turbomachinery component testing and performance measurements. The current work aims to evaluate the static load performance of 3D-printed hybrid bearings lubricated with a compressible fluid. The test bearing, fabricated using Fused deposition modeling (FDM) technology and embedded with onyx and ~35% carbon fibers, has flat surfaces with inner and outer diameters equal to 63 mm and 145 mm, respectively. The bearing has uniformly distributed eight pockets on the bearing circumference with 90 mm in mean diameter, 20-degree in arc length, and 0.51 mm in depth. The simple component-level bearing test facility allows to test and evaluate the current bearing design with various load and fluid property conditions. The measured bearing static load characteristics are quite similar to the bearing fabricated with a subtractive manufacturing process. The measured static load performance of the test bearings is compared to experimental data.
The current predictions use measured bearing geometries and actual operating conditions. The future work accesses the feasibility of direct metal laser melting (DMLM) technology in the fabrication of complicated hybrid fluid film bearings with high load capacity and damping capabilities for cryogenic turbopumps in reusable and low-cost rocket engines. Experimentally validated predictive bearing models significantly reduce time and expenses in further developments of hybrid cryogenic bearings, and aid to reduce the variability in identically constructed test bearing units while also certifying their scalability.
Evaluation of Abd®-900am for Gas Turbine Additive Manufacturing & Repair:
John Shingledecker, Electric Power Research Institute
Most studies on the application of additive manufacturing (AM) of nickel-based superalloys for gas turbine hardware utilize traditional material compositions. In this work, the Electric Power Research Institute (EPRI) is evaluating a new alloy, ABD®-900AM, which was specifically developed for combined 'printability' as well as high-temperature performance.
Prior EPRI research on gas turbine guide vanes produced by Laser Powder Fusion Bed (LPFB) processes showed good tensile and fatigue behavior but significant debits in time-dependent creep strength reductions compared to traditional casting.
Detailed microstructural analysis on long-term creep tested samples identified specific microstructural features including grain size and carbide size and distribution which appear to be the source of the loss of long-term performance.
Thus, the focus of this work was to understand how process selection and post-process variables effect microstructure and high-temperature time dependent creep performance in ABD900AM with a focus on high-temperature applications with the potential for component repair and replacement.
Specifically, EPRI is evaluating both LPFB and Electron Beam (EB) processes and multiple sub and super-solvus heat-treatments. ABD900AM was selected for this study since it has demonstrated superior printability and repair potential for LPFB processes.
The EB process has the potential to grow 'directionally solidified' (DS) type structures which are known to improve creep performance. To date, creep tests have been conducted on 5 different processing and post-processing conditions showing a significant variation in microstructure and creep performance.
This talk will highlight the findings to date, comparisons of microstructures and data with traditional cast blade and vane materials, and provide a prognosis for future AM applications in gas turbine hot-section components.
A Simple Cost Model to Drive Design for Additive Manufacturing:
Timothy W. Simpson, Penn State University
Designing for additive manufacturing (AM) is as much about maximizing the value afforded by layer-wise fabrication processes that AM provides as it is about minimizing the costs associated with them. While our understanding of Design for AM (DfAM) has matured rapidly over the past decade as software tools and methods have evolved, we still struggle to translate this into direct economic benefit, which is key to successful implementation of AM.
In this talk, I will introduce a simple cost model for metal AM, specifically laser powder bed fusion, that can help drive DfAM decisions and enable DfAM trade studies. Despite its simplicity, the simple cost model provides a guide to identify profitable pathways to AM. If none of those pathways are immediately profitable, then the cost model provides insight into when the part will become viable as other economic factors (e.g., material costs, machine cost) or technical factors (e.g., laser powder, number of lasers) fluctuate in the market.
An example from an industry training exercise will be discussed to demonstrate application of the costing guide to achieve a viable AM part when using DfAM. The example also illustrates how DfAM is the “value multiplier” for AM, helping to achieve a profitable AM part faster and with more control than waiting for powder costs to come down or and machine prices to fall.
Generalizability of the costing guide to other AM processes will also be discussed.
Novel Ultrasonic Based Technology for Support Removal and Post-Processing for Additive Manufacturing:
Tomasz Choma, AMAZEMET
One of the most important steps in AM besides the printing itself is post-processing. Complex geometries often require a large number of support structures that may be problematic to remove mechanically after the printing process. This issue limits the design possibilities and highly increases the production cost of each part.
Automated support removal platform uses chemical etchants with ultrasonic agitation to dissolve support structures, remove leftover or not fully melted powder reducing the roughness of the surface, and penetrate inaccessible areas. The process is simple and does not require any additional wiring or set up of elements in the reactor. The system allows for quick support removal of multiple elements at the same time, thus it highly reduces the processing cost and time for each part in the manufacturing chain process.
The safeEtch allows users to automatically remove supports without mechanical treatment and polishes surfaces even in places inaccessible with classical tools. Technology is based on chemical reactions accelerated with high-intensity ultrasounds. Mass production with SLM/PBF/DMLS is often limited to a single layer of printouts while stacking has been an advantage of EBM technology. With safeEtch it is true no more. Having an effect of dissolvable supports we can freely stack multiple elements in the Z-axis without worrying about time consuming post-processing.
Applied Materials Corrosion:
lance Scudder, Applied Materials
Applied Materials specializes in solving exceptionally difficult materials engineering challenges in a high-volume manufacturing environment. Our solutions include coating deposition and removal, automation software, and metrology for productivity & performance.
Applied Materials has developed and commercialized a variety of barrier coatings for a range of end-market applications. Here, we demonstrate novel barrier coatings developed for the semiconductor industry that have applicability for aerospace & land-based gas turbine engine applications.
The barrier coatings described have several unique properties, including a high degree of conformality, the ability to coat blind passages, and significantly reduced corrosion rates on superalloy substrates. Applied Materials coatings are significantly thinner than an oxide scale at the spallation thickness threshold of 5-10 μm, so the coatings have minimal material impact on weight and geometric tolerances of finished components.
Applied Materials has developed a CVD deposition process that overcomes several process limitations of other corrosion protective coatings. The process results in a highly conformal coating at both the macro and microscale. In this presentation we will demonstrate coating the exterior and interior of a turbine blade with a 40:1 aspect ratio and a fully blind “U” turn. Coating thickness variation is less than ±13% on the interior of the component. In addition, the coating is able to conformally coat rough surface topology typically seen with as-cast or 3D printed surfaces.
We tested coated and uncoated CMSX-4 (SLS) nickle superalloy in high temperature Type I hot corrosion at 900 °C in air, with a deposit of a eutectic mixture of MgSO4-Na2SO4 salts. In this presentation, we detail mass change, optical top view and SEM cross-section characterization of samples used during corrosion testing. The overall time to failure is at least 2.5x longer with the Applied Materials coating vs. uncoated nickel superalloy.
Working with AERO OEM and MRO industry partners, we have successfully demonstrated application of this unique corrosion resistant coating in manufacturing integration testing with AERO turbine blades for use in aircraft engine hot sections.