Proof-Of-Concept of a Thermal Barrier Coated Titanium Cooling Layer for an Inside-Out Ceramic Turbine

2021 ◽  
Author(s):  
Antoine Gauvin-Verville ◽  
Patrick K. Dubois ◽  
Benoit Picard ◽  
Alexandre Landry-Blais ◽  
Jean-Sébastien Plante ◽  
...  
Keyword(s):  
Polymer Composite ◽  
Safety Factor ◽  
Gas Turbines ◽  
High Efficiency ◽  
Cooling Power ◽  
Thermal Barrier ◽  
Inlet Temperature ◽  
Turbine Stage ◽  
Minimum Safety Factor ◽  
Inside Out

Abstract Increasing turbine inlet temperature (TIT) of recuperated gas turbines would lead to simultaneously high efficiency and power density, making them prime candidates for low-emission aeronautics applications, such as hybrid-electric aircraft. The Inside-out Ceramic Turbine (ICT) architecture achieves high TIT by using compression-loaded monolithic ceramics. To resist inertial forces due to blade tip speed exceeding 450 m/s, the shroud of the ICT is made of carbon-polymer composite, wound around a metallic cooling ring. This paper demonstrates that it is beneficial to use a titanium alloy cooling ring with a thermal barrier coating (TBC), rather than nickel superalloys, for the interstitial cooling ring protecting the carbon-polymer from the hot combustion gases. A numerical Design of Experiments (DOE) analysis shows the design trade-offs between the minimum safety factor and the required cooling power for multiple geometries. An optimized high-pressure first turbine stage of a 500 kW microturbine concept using ceramic blades and a titanium cooling ring in an ICT configuration is presented. Its structural performance (minimum safety factor of 1.4) as well as its cooling losses (2% of turbine stage power) are evaluated. Finally, a 20 kW-scale prototype is tested at 300 m/s and a TIT of 1375 K during 4hrs to demonstrate the viability of the concept. Experiments show that the polymer composite was kept below its maximum safe operating temperature and components show no early signs of degradation.

Proof-Of-Concept of a Thermal Barrier Coated Titanium Cooling Layer for an Inside-Out Ceramic Turbine

2021 ◽  
Author(s):  
Antoine Gauvin-Verville ◽  
Patrick K. Dubois ◽  
Benoit Picard ◽  
Alexandre Landry-Blais ◽  
Jean-Sébastien Plante ◽  
...  
Keyword(s):  
Polymer Composite ◽  
Safety Factor ◽  
Gas Turbines ◽  
High Efficiency ◽  
Cooling Power ◽  
Thermal Barrier ◽  
Inlet Temperature ◽  
Turbine Stage ◽  
Minimum Safety Factor ◽  
Inside Out

Abstract Increasing turbine inlet temperature (TIT) of recuperated gas turbines would lead to simultaneously high efficiency and power density, making them prime candidates for low-emission aeronautics applications, such as hybrid-electric aircraft. The Inside-out Ceramic Turbine (ICT) architecture achieves high TIT by using compression-loaded monolithic ceramics. To resist inertial forces due to blade tip speed exceeding 450 m/s, the shroud of the ICT is made of carbon-polymer composite, wound around a metallic cooling ring. This paper demonstrates that it is beneficial to use a titanium alloy cooling ring with a thermal barrier coating (TBC), rather than nickel superalloys, for the interstitial cooling ring protecting the carbon-polymer from the hot combustion gases. A numerical Design of Experiments (DOE) analysis shows the design trade-offs between the minimum safety factor and the required cooling power for multiple geometries. An optimized high-pressure first turbine stage of a 500 kW microturbine concept using ceramic blades and a titanium cooling ring in an ICT configuration is presented. Its structural performance (minimum safety factor of 1.4) as well as its cooling losses (2% of turbine stage power) are evaluated. Finally, a 20 kW-scale prototype is tested at 300 m/s and a TIT of 1375 K during 4hrs to demonstrate the viability of the concept. Experiments show that the polymer composite was kept below its maximum safe operating temperature and components show no early signs of degradation.

Three Spool High Efficiency Small Scale Gas Turbine Concept

2017 ◽  
Author(s):  
Matti Malkamäki ◽  
Ahti Jaatinen-Värri ◽  
Antti Uusitalo ◽  
Aki Grönman ◽  
Juha Honkatukia ◽  
...  
Keyword(s):  
Power Generation ◽  
Gas Turbine ◽  
Gas Turbines ◽  
High Efficiency ◽  
Small Scale ◽  
Inlet Temperature ◽  
Substantial Impact ◽  
Electrical Efficiency ◽  
Partial Load ◽  
Reciprocating Engines

Decentralized electricity and heat production is a rising trend in small-scale industry. There is a tendency towards more distributed power generation. The decentralized power generation is also pushed forward by the policymakers. Reciprocating engines and gas turbines have an essential role in the global decentralized energy markets and improvements in their electrical efficiency have a substantial impact from the environmental and economic viewpoints. This paper introduces an intercooled and recuperated three stage, three-shaft gas turbine concept in 850 kW electric output range. The gas turbine is optimized for a realistic combination of the turbomachinery efficiencies, the turbine inlet temperature, the compressor specific speeds, the recuperation rate and the pressure ratio. The new gas turbine design is a natural development of the earlier two-spool gas turbine construction and it competes with the efficiencies achieved both with similar size reciprocating engines and large industrial gas turbines used in heat and power generation all over the world and manufactured in large production series. This paper presents a small-scale gas turbine process, which has a simulated electrical efficiency of 48% as well as thermal efficiency of 51% and can compete with reciprocating engines in terms of electrical efficiency at nominal and partial load conditions.

Superalloy Cooling System for the Composite Rim of an Inside-Out Ceramic Turbine

2017 ◽  
Author(s):  
N. Courtois ◽  
F. Ebacher ◽  
P. K. Dubois ◽  
N. Kochrad ◽  
C. Landry ◽  
...  
Keyword(s):  
Gas Turbines ◽  
Cooling System ◽  
High Strength ◽  
Carbon Composite ◽  
Flow Rate Ratio ◽  
Small Scale ◽  
Inlet Temperature ◽  
Operating Temperatures ◽  
Critical Components ◽  
Inside Out

The use of ceramics in gas turbines potentially allows for very high cycle efficiency and power density, by increasing operating temperatures. This is especially relevant for sub-megawatt gas turbines, where the integration of complex blade cooling greatly affects machine capital cost. However, ceramics are brittle and prone to fragile, catastrophic failure, making their current use limited to static and low-stress parts. Using the inside-out ceramic turbine (ICT) configuration solves this issue by converting the centrifugal blade loading to compressive stress, by using an external high-strength carbon-polymer composite rim. This paper presents a superalloy cooling system designed to protect the composite rim and allow it to withstand operating temperatures up to 1600 K. The cooling system was designed using one-dimensional (1D) models, developed to predict flow conditions as well as the temperatures of its critical components. These models were subsequently supported with computational fluid dynamics and used to conduct a power scalability study on a single stage ICT. Results suggest that the ICT configuration should achieve a turbine inlet temperature (TIT) of 1600 K with a composite rim cooling-to-main mass flow rate ratio under 5.2% for power levels above 350 kW. A proof of concept was performed by experimental validation of a small-scale 15 kW prototype, using a commercially available bismaleimide-carbon (BMI-carbon) composite rim and Inconel® 718 nickel-based alloy. The combination of numerical and experimental results show that the ICT can operate at a TIT of 1100 K without damage to the composite rim.

scholarly journals Analytical and Experimental Study of Residual Stresses in Thermal Barrier Coatings Deposited on Gas Turbine Blades in Laboratory Dimensions by APS and HVOF Methods to Calculate the Optimal Thickness

2021 ◽  
Vol 3 (1) ◽  
pp. 63-67
Author(s):  
Esmaeil Poursaeidi ◽  
◽  
Farzam Montakhabi ◽  
Javad Rahimi ◽  
◽  
...  
Keyword(s):  
Residual Stress ◽  
Residual Stresses ◽  
Analytical Model ◽  
Thermal Barrier Coatings ◽  
Gas Turbines ◽  
Turbine Blades ◽  
Thermal Barrier ◽  
Inlet Temperature ◽  
Optimal Thickness ◽  
Barrier Coatings

The constant need to use gas turbines has led to the need to increase turbines' inlet temperature. When the temperature reaches a level higher than the material's tolerance, phenomena such as creep, changes in mechanical properties, oxidation, and corrosion occur at high speeds, which affects the life of the metal material. Nowadays, operation at high temperatures is made possible by proceedings such as cooling and thermal insulation by thermal barrier coatings (TBCs). The method of applying thermal barrier coatings on the turbine blade creates residual stresses. In this study, residual stresses in thermal barrier coatings applied by APS and HVOF methods are compared by Tsui–Clyne analytical model and XRD test. The analytical model results are in good agreement with the experimental results (between 2 and 8% error), and the HVOF spray method creates less residual stress than APS. In the end, an optimal thickness for the coating is calculated to minimize residual stress at the interface between the bond coat and top coat layers.

Flameholding Tendencies of Natural Gas and Hydrogen Flames at Gas Turbine Premixer Conditions

2014 ◽  
Author(s):  
Elliot Sullivan-Lewis ◽  
Vincent McDonell
Keyword(s):  
Natural Gas ◽  
Gas Turbine ◽  
Gas Turbines ◽  
High Efficiency ◽  
High Reliability ◽  
Elevated Pressure ◽  
Inlet Temperature ◽  
Increased Risk ◽  
Wide Range ◽  
Lean Premixed

Ground based gas turbines are responsible for generating a significant amount of electric power as well as providing mechanical power for a variety of applications. This is due to their high efficiency, high power density, high reliability, and ability to operate on a wide range of fuels. Due to increasingly stringent air quality requirements, stationary power gas turbines have moved to lean-premixed operation. Lean-premixed operation maintains low combustion temperatures for a given turbine inlet temperature, resulting in low NOx emissions while minimizing emissions of CO and hydrocarbons. In addition, to increase overall cycle efficiency, engines are being operated at higher pressure ratios and/or higher combustor inlet temperatures. Increasing combustor inlet temperatures and pressures in combination with lean-premixed operation leads to increased reactivity of the fuel/air mixture, leading to increased risk of potentially damaging flashback. Curtailing flashback on engines operated on hydrocarbon fuels requires care in design of the premixer. Curtailing flashback becomes more challenging when fuels with reactive components such as hydrogen are considered. Such fuels are gaining interest because they can be generated from both conventional and renewable sources and can be blended with natural gas as a means for storage of renewably generated hydrogen. The two main approaches for coping with flashback are either to design a combustor that is resistant to flashback, or to design one that will not anchor a flame if a flashback occurs. An experiment was constructed to determine the flameholding tendencies of various fuels on typical features found in premixer passage ways (spokes, steps, etc.) at conditions representative of a gas turbine premixer passage way. In the present work tests were conducted for natural gas and hydrogen between 3 and 9 atm, between 530 K and 650K, and free stream velocities from 40 to 100 m/s. Features considered in the present study include a spoke in the center of the channel and a step at the wall. The results are used in conjunction with existing blowoff correlations to evaluate flameholding propensity of these physical features over the range of conditions studied. The results illustrate that correlations that collapse data obtained at atmospheric pressure do not capture trends observed for spoke and wall step features at elevated pressure conditions. Also, a notable fuel compositional effect is observed.

Application of a High Order LES Approach to the Redistribution of Inlet Temperature Distortion in a Turbine

2013 ◽  
Author(s):  
Debasish Biswas ◽  
Aya Kitoh
Keyword(s):  
Gas Turbines ◽  
Fluid Dynamic ◽  
Measurement Techniques ◽  
High Order ◽  
Numerical Results ◽  
Cycle Performance ◽  
Inlet Temperature ◽  
Clear Understanding ◽  
Turbine Stage ◽  
Mean Flow

The demand of an increase in the cycle performance of today’s gas turbines creates severe heat loads in the first turbine stage, since higher operating temperatures are required. The mean flow temperature is usually well above the limit supported by the surrounding material. Cooling of both end-walls and the blades of the first stage is thus usually necessary. Consequently, mid-span streaks of hot gas pass through the first stator row and become hot jets of fluid. Also, the exit flow from a gas turbine combustor entering a turbine stage can have a wide variation in temperature. These variations may be both spatial and temporal. The implementation of cooling method requires a clear understanding of the aerodynamics involved. Both qualitative and quantitative assessments of the redistribution of inlet temperature distortions can be used to considerable advantage by the turbine designer. Experimentally it has been demonstrated that the rotor actually separates the hotter and cooler streams of fluid so that a hotter fluid migrates toward the pressure surface and cooler fluid migrates towards the suction surface. The main purpose of this study is to test the performance of a high-order LES model in terms of predicting this type of highly complicated unsteady flow and heat transfer phenomena. This work describes the performance of a high-order Large Eddy Simulation (LES) turbulent model (developed by the first author) related to the prediction of above mentioned redistribution of inlet temperature distortion in an experimental turbine. Because the understanding of the physical phenomena associated with this temperature redistribution behavior is a very challenging computational fluid dynamic problem. If the numerical method could predict the precisely measured data satisfactorily, then the fluid dynamic variables which are difficult to measure (but obtained as computed results) could be used to visualize the flow characteristics. This technique will also help to get rid off indirect measurement techniques with large measurement uncertainty. In our study emphasis is put to predict the unsteady turbulence characteristics. In this work 3-D unsteady Navier-Stokes analysis of a turbine stage (satisfying the experimental stator-rotor blade ratio) is carried out to study the above mentioned phenomena. The numerical results predicted the experimentally observed phenomena very well. The fact that the streamlines in the stator row remain unaffected was demonstrated by the numerical results. The measured characteristics of the streamline patterns in the rotor row resulted from the secondary flow effect and consequently the inlet temperature distortion effect is also very well predicted.

Thermal Barrier Coating Applied to the Structural Shroud of an Inside-Out Ceramic Turbine

2021 ◽  
Author(s):  
P. K. Dubois ◽  
A. Gauvin-Verville ◽  
B. Picard ◽  
J.-S. Plante ◽  
M. Picard
Keyword(s):  
High Temperature ◽  
Thermal Barrier Coating ◽  
Internal Surface ◽  
Small Scale ◽  
Thermal Barrier ◽  
Inlet Temperature ◽  
Air Plasma ◽  
Barrier Coating ◽  
Deformation Mechanics ◽  
Inside Out

Abstract Recuperated, high-temperature microturbines (< 1 MW) could be a key enabler for hybrid powertrains of tomorrow’s small aircraft. To achieve competitive thermal efficiencies, turbine inlet temperature (TIT) must increase to 1550 K, well beyond conventional metallic microturbine limits. This calls for high-temperature refractory ceramics, which call for a new ceramic-specific, microturbine design like the Inside-Out Ceramic Turbine (ICT). This study focuses on the applicability of a refractory thermal barrier coating (TBC) to the internal surface of the ICT cooling ring. By cutting the heat transfer from the main flow to the structural rim-rotor, the use of a refractory TBC coating in an ICT enables higher TIT and lower cooling air mass flow. A preliminary experimental assessment is done at room temperature on 1 mm-thick coatings of 8% yttria-stabilized zirconia (8YSZ), air plasma sprayed (APS) TBC, applied to Inconel 718 and Ti64 test coupons. Results show that the strongly orthotropic behaviour of the tested TBC fits perfectly with the deformation mechanics of the ICT configuration under load. First, large in-plane strain tolerance allows the large tangential deformation imposed by the structural shroud under centrifugal loading. Second, high out-of-plane stiffness and compressive resistance combine to support extreme compressive loads with no apparent damage to the TBC even at more than 3 times blade indentation average loading. An experimental demonstration on a small-scale prototype shows a reduction of 40% in cooling flow in a, 8-minute ICT test, with no damage to the TBC, proving the effectiveness and potential of the proposed TBC design.

The Energy Exchanger, a New Concept for High-Efficiency Gas Turbine Cycles

1967 ◽  
Vol 89 (2) ◽  
pp. 217-227 ◽  
Author(s):  
R. C. Weatherston ◽  
A. Hertzberg
Keyword(s):  
Gas Turbine ◽  
Gas Turbines ◽  
Energy Exchange ◽  
High Efficiency ◽  
Inlet Temperature ◽  
Viscous Effects ◽  
Isentropic Compression ◽  
Combustion Gas ◽  
Power Cycles ◽  
Compression Waves

A method of circumventing the turbine inlet temperature limitation of present-day gas turbines is presented. This method is based on a direct fluid-to-fluid energy exchanger whereby the available energy of expansion of the hot combustion gas in a gas turbine cycle is transferred directly to a colder gas. The aerodynamic wave processes in several possible modes of operation are examined to determine the inherent limitations in efficiency of direct fluid-to-fluid energy exchange processes. In particular, it is demonstrated that, by using a system of isentropic compression waves to avoid shock losses and by carefully choosing the molecular weights of the fluids utilized in the energy exchanger, perfect energy exchange is possible in principle. When allowances are made for losses due to mixing, leakage, and viscous effects, an energy exchanger utilizing heated combustion air at 3240 deg F to drive steam at 1500 deg F with a potential energy exchange efficiency of 85 percent is feasible. Applications of the air-steam energy exchanger operating in gas turbine cycles utilizing a conservative choice of component efficiencies indicate that thermal efficiencies of gas turbine power cycles of 50–60 percent may be possible.

scholarly journals Development of a High Pressure Ratio Centrifugal Compressor for 300kW-Class Ceramic Gas Turbine

1997 ◽  
Author(s):  
T. Sakai ◽  
Y. Tohbe ◽  
T. Fujii ◽  
T. Tatsumi
Keyword(s):  
Research And Development ◽  
Gas Turbine ◽  
Gas Turbines ◽  
High Efficiency ◽  
Pressure Ratio ◽  
Flow Distribution ◽  
Leading Edge ◽  
Inlet Temperature ◽  
Angle Distribution ◽  
Gas Generator

Research and development of ceramic gas turbines (CGT), which is promoted by the Japanese Ministry of International Trade and Industry (MITI), was started in 1988. The target of the CGT project is development of a 300kW-class ceramic gas turbine with a 42 % thermal efficiency and a turbine inlet temperature (TIT) of 1350°C. Two types of CGT engines are developed in this project. One of the CGT engines, which is called CGT302, is a recuperated two-shaft gas turbine with a compressor, a gas-generator turbine, and a power turbine for cogeneration. In this paper, we describe the research and development of a compressor for the CGT302. Specification of this compressor is 0.89 kg/sec air flow rate and 8:1 pressure ratio. The intermediary target efficiency is 78% and the final target efficiency is 82%, which is the highest level in email centrifugal compressors like this one. We measured impeller inlet and exit flow distribution using three-hole yaw probes which were traversed from the shroud to the hub. Based on the measurement of the impeller exit flow, diffusers with a leading edge angle distribution adjusted to the inflow angle were designed and manufactured. Using this diffuser, we were able to attain a high efficiency (8:1 pressure ratio and 78% adiabatic efficiency).

scholarly journals Experimental Assessment of a Sliding-Blade Inside-Out Ceramic Turbine

2020 ◽  
Author(s):  
Dominik Thibault ◽  
Patrick K. Dubois ◽  
Benoit Picard ◽  
Alexandre Landry-Blais ◽  
Jean-Sébastien Plante ◽  
...  
Keyword(s):  
High Efficiency ◽  
Cost Effective ◽  
Inlet Temperature ◽  
Brayton Cycle ◽  
Low Friction ◽  
Turbine Inlet Temperature ◽  
Blade Loading ◽  
Rotor Design ◽  
Inside Out ◽  
Acceptable Reliability

Abstract In order to reach 40% efficiency, sub-MW turbines must operate in a recuperated gas Brayton cycle at a turbine inlet temperature (TIT) above 1300°C. Current sub-MW turbines have material-related operating temperature limits. Still to this day, there is no cost-effective rotor design which operates at such high temperatures. This paper introduces a novel, sliding-blade, inside-out ceramic turbine (ICT) wheel configuration, which could enable high-efficiency sub-MW recuperated engines to be achieved with cheap monolithic ceramic blades. The inside-out configuration uses a rotating structural hoop, or shroud, to convert centrifugal forces into compressive blade loading. The sliding-blade architecture uses a hub with angled planes on which ceramic blades slide up and down, allowing to match the radial expansion of the structural shroud. This configuration generates low stress values in both ceramic and metallic components and can achieve high tip speeds. A prototype is designed and its reliability is calculated using CARES software. The result is a design which has a single blade probability of failure (Pf) of 0.1% for 1000 h of steady operation. Analyses also demonstrate that reliability is greatly dependent on friction at ceramic-to-metal interfaces. Low friction could lead to acceptable reliability levels for engine applications. The prototype was successfully tested in a laboratory turbine environment at a tip speed of 350 m/s and a TIT of 1100 °C without any damage.

Sign in / Sign up

Export Citation Format

Share Document