Design Overview of a Three-Kilowatt Recuperated Ceramic Turboshaft Engine

2009 ◽  
Author(s):  
Michael J. Vick ◽  
Andrew Heyes ◽  
Keith Pullen
Keyword(s):  
Silicon Nitride ◽  
Gas Turbines ◽  
Pressure Ratio ◽  
Cost Effective ◽  
Ceramic Materials ◽  
Combustion Products ◽  
Multistage Turbine ◽  
Ceramic Recuperator ◽  
Ic Engines ◽  
Turboshaft Engine

A three-kilowatt turboshaft engine with a ceramic recuperator and turbine has been designed for small unmanned air vehicle (UAV) propulsion and portable power generation. Compared with internal combustion (IC) engines, gas turbines offer superior reliability, engine life, noise and vibration characteristics, and compatibility with military fuels. However, the efficiency of miniature gas turbines must be improved substantially, without severely compromising weight and cost, if they are to compete effectively with small IC engines for long-endurance UAV propulsion. This paper presents a design overview and supporting analytical results for an engine that could meet this goal. The system architecture was chosen to accommodate the limitations of mature, cost-effective ceramic materials: silicon nitride for the turbine rotors, and toughened mullite for the heat exchanger and turbine stators. An engine with a cycle pressure ratio below 2:1, a multistage turbine, and a highly effective recuperator is shown to have numerous advantages in this context. A key benefit is a very low water-vapor-induced surface recession rate for silicon nitride, due to an extremely low partial pressure of water in the combustion products. Others include reduced sensitivity to internal flaws, creep, and foreign object damage; an output shaft speed low enough for grease-lubricated bearings; and the potential viability of a novel premixed heat-recirculating combustor.

Design Overview of a Three Kilowatt Recuperated Ceramic Turboshaft Engine

2010 ◽  
Vol 132 (9) ◽  
Author(s):  
Michael J. Vick ◽  
Andrew Heyes ◽  
Keith Pullen
Keyword(s):  
Silicon Nitride ◽  
Gas Turbines ◽  
Pressure Ratio ◽  
Cost Effective ◽  
Ceramic Materials ◽  
Combustion Products ◽  
Multistage Turbine ◽  
Ceramic Recuperator ◽  
Ic Engines ◽  
Turboshaft Engine

A three kilowatt turboshaft engine with a ceramic recuperator and turbine has been designed for small unmanned air vehicle (UAV) propulsion and portable power generation. Compared with internal combustion (IC) engines, gas turbines offer superior reliability, engine life, noise and vibration characteristics, and compatibility with military fuels. However, the efficiency of miniature gas turbines must be improved substantially, without severely compromising weight and cost, if they are to compete effectively with small IC engines for long-endurance UAV propulsion. This paper presents a design overview and supporting analytical results for an engine that could meet this goal. The system architecture was chosen to accommodate the limitations of mature, cost-effective ceramic materials: silicon nitride for the turbine rotors and toughened mullite for the heat exchanger and turbine stators. An engine with a cycle pressure ratio below 2:1, a multistage turbine, and a highly effective recuperator is shown to have numerous advantages in this context. A key benefit is a very low water vapor-induced surface recession rate for silicon nitride, due to an extremely low partial pressure of water in the combustion products. Others include reduced sensitivity to internal flaws, creep, and foreign object damage; an output shaft speed low enough for grease-lubricated bearings; and the potential viability of a novel premixed heat-recirculating combustor.

Reliability of a Conceptual Ceramic Gas Turbine Component Subjected to Static and Transient Thermomechanical Loading

1997 ◽  
Author(s):  
Paul S. DiMascio ◽  
Robert M. Orenstein ◽  
Harindra Rajiyah
Keyword(s):  
Silicon Nitride ◽  
Gas Turbine ◽  
Gas Turbines ◽  
Ceramic Materials ◽  
Combustion Products ◽  
Tensile Creep ◽  
Creep Model ◽  
Gas Combustion ◽  
Component Reliability ◽  
Reliability Models

A three year program to evaluate the feasibility of using monolithic silicon nitride ceramic components in gas turbines was conducted. The use of ceramic materials may enable design of turbine components which operate at higher gas temperatures and/or require less cooling air than their metal counterparts. The feasibility evaluation consisted of three tasks: 1) Expand the material properties database for candidate silicon nitride materials, 2) Demonstrate the ability to predict ceramic reliability and life using a conceptual component model and 3) Evaluate the effect of proof testing on conceptual component reliability. The overall feasibility goal was to determine whether established life and reliability targets could be satisfied for the conceptual ceramic component having properties of an available material. Fast and delayed fracture reliability models were developed and validated via thermal shock and tensile experiments. A creep model was developed using tensile creep data. The effect of oxidation was empirically evaluated using four-point flexure samples exposed to flowing natural gas combustion products. The reliability- and life-limiting failure mechanisms were characterized in terms of temperature, stress and probability of component failure. Conservative limits for design of silicon nitride gas turbine components were established.

Reliability of a Conceptual Ceramic Gas Turbine Component Subjected to Static and Transient Thermomechanical Loading

1998 ◽  
Vol 120 (2) ◽  
pp. 263-270 ◽  
Author(s):  
P. S. DiMascio ◽  
R. M. Orenstein ◽  
H. Rajiyah
Keyword(s):  
Silicon Nitride ◽  
Gas Turbine ◽  
Gas Turbines ◽  
Ceramic Materials ◽  
Combustion Products ◽  
Tensile Creep ◽  
Creep Model ◽  
Gas Combustion ◽  
Component Reliability ◽  
Reliability Models

A three year program to evaluate the feasibility of using monolithic silicon nitride ceramic components in gas turbines was conducted. The use of ceramic materials may enable design of turbine components which operate at higher gas temperatures and/or require less cooling air than their metal counterparts. The feasibility evaluation consisted of the following three tasks: (1) expand the materials properties database for candidate silicon nitride materials; (2) demonstrate the ability to predict ceramic reliability and life using a conceptual component model; and (3) evaluate the effect of proof testing on conceptual component reliability. The overall feasibility goal was to determine whether established life and reliability targets could be satisfied for the conceptual ceramic component having properties of an available material. Fast and delayed fracture reliability models were developed and validated via thermal shock and tensile experiments. A creep model was developed using tensile creep data. The effect of oxidation was empirically evaluated using four-point flexure samples exposed to flowing natural gas combustion products. The reliability and life-limiting failure mechanisms were characterized in terms of temperatures, stress, and probability of component failure. Conservative limits for design of silicon nitride gas turbine components were established.

Quantitative Phase Analysis of Synthetic Silicon Nitride by X-Ray Diffraction

1979 ◽  
Vol 23 ◽  
pp. 375-379
Author(s):  
Z. Mencik ◽  
M. A. Short ◽  
C. R. Peters
Keyword(s):  
Silicon Nitride ◽  
Phase Analysis ◽  
Gas Turbines ◽  
Ceramic Materials ◽  
Silicon Oxynitride ◽  
Quantitative Phase Analysis ◽  
X Ray Diffraction ◽  
X Ray ◽  
Quantitative Phase ◽  
Typical Material

Synthetically prepared silicon nitride is one of the more promising ceramic materials for structural components of gas turbines. Typical material may contain a-silicon nitride, Si3N4 (which is believed to always contain oxygen and therefore, according to Grievson, Jack and Wild, is more properly written as Si11.5N15O0.5), β-silicon nitride, Si3N4, silicon oxynitride, Si2ON2, silicon metal, Si, and α-cristobalite, SiO2. Because the physical properties of the ceramic parts are dependent on their phase composition, it is essential that a technique be available for performing a phase analysis. An X-ray diffraction procedure has been, developed for the quantitative phase analysis of synthetically prepared silicon nitride. This procedure converts experimentally measured intensities of selected X-ray diffraction peaks to weight fractions of components using empirically determined intensity coefficients.

scholarly journals Improved Silicon Nitride Materials and Component Fabrication Processes for Aerospace and Industrial Gas Turbine Applications

1995 ◽  
Author(s):  
John P. Pollinger
Keyword(s):  
Silicon Nitride ◽  
Gas Turbine ◽  
Gas Turbines ◽  
Hybrid Electric Vehicle ◽  
Ceramic Materials ◽  
Production Volume ◽  
Cycle Times ◽  
Fine Grained ◽  
Auxiliary Power Units ◽  
Industrial Gas Turbines

New and improved silicon nitride structural ceramic materials and component fabrication processes are being developed and refined for implementation and insertion into aerospace, industrial, and automotive gas turbine applications. These improved materials and forming processes offer the potential of meeting turbomachinery manufacturers’ performance, quality, cost, and production volume goals. AlliedSignal has developed a new generation of silicon nitride materials with isotropic acicular microstructures that result in a number of property improvements compared to current HIP’ed fine-grained silicon nitride materials. Concurrently, new silicon nitride component forming processes such as gelcasting and refinements of current forming processes such as presintered component machining are being developed and refined to achieve production volume fabrication capability, yields, and short cycle times at low costs. As these materials and component fabrication processes are maturating, a number of applications are being investigated and demonstrated including hot section turbomachinery components for aircraft auxiliary power units (APU’s), industrial gas turbines, and automotive hybrid electric vehicle turboalternators.

Ceramic Stationary Gas Turbine Development

1993 ◽  
Author(s):  
Mark van Roode ◽  
William D. Brentnall ◽  
Paul F. Norton ◽  
Gregory P. Pytanowski
Keyword(s):  
Silicon Carbide ◽  
Silicon Nitride ◽  
Gas Turbine ◽  
Gas Turbines ◽  
Ceramic Materials ◽  
Ceramic Composites ◽  
Department Of Energy ◽  
Engine Operation ◽  
Component Design ◽  
Combustor Liner

A program has been initiated under the sponsorship of the Department of Energy (DOE), Office of Industrial Technology, to improve the performance of stationary gas turbines in cogeneration through the selective replacement of metallic hot section parts with uncooled ceramic components. It is envisioned that the successful demonstration of ceramic gas turbine technology, and the systematic incorporation of ceramics in existing and future gas turbines will enable more efficient engine operation, resulting in significant fuel savings, increased output power, and reduced emissions. The program which started in September, 1992, takes an engine of the Solar Centaur family of industrial gas turbines, and modifies the design of the hot section to accept ceramic first stage blades and first stage nozzles, and a ceramic combustor liner. The ceramic materials selected for the blade are silicon nitride, for the nozzle silicon nitride and silicon carbide, and for the combustor liner silicon carbide as well as two continuous fiber reinforced ceramic composites, one with a silicon carbide matrix and another with an oxide matrix. This paper outlines the approach, conceptual component design, and materials selection for the program.

Ceramic Recuperator and Turbine: The Key to Achieving a 40 Percent Efficient Microturbine

2005 ◽  
Author(s):  
Colin F. McDonald ◽  
Colin Rodgers
Keyword(s):  
Gas Turbines ◽  
Pressure Ratio ◽  
Development Program ◽  
Metallic Component ◽  
Distributed Power Generation ◽  
Ceramic Components ◽  
Ceramic Recuperator ◽  
The Government ◽  
Upper Level ◽  
Flow Components

Based on the use of state-of-the-art component technologies and the use of existing metallic materials, achieving an electrical efficiency anywhere near 40 percent in low pressure ratio recuperated microturbines is proving elusive. Current microturbines, rated at say 100 kW, operate with efficiencies approaching 30 percent. Advancing this to an upper level of about 35 percent is projected based on the ability to operate at turbine inlet temperatures greater than 1100C, and the utilization of a higher cost superalloy recuperator. This paper puts into perspective the challenge of trying to achieve 40 percent efficiency for small recuperated turbogenerator designs with radial flow components; the major constraints being associated with stress limitations in both the turbine and recuperator. Various publications (issued by both industry and the Government) often mention an efficiency goal of 40 percent for small gas turbines of this configuration, however, it needs to be recognized that the means to achieve this are beyond current high temperature metallic component capabilities. To achieve this “goal” necessitates increasing the operating temperature of the turbine and recuperator above 1100C and 800C respectively. Such advancements are projected to be technically and cost-effectively achievable by utilizing ceramic components, which with a dedicated development program, could perhaps become a reality in less than a decade to meet both future distributed power generation needs and defense applications, and be in concert with ever-demanding conservation goals and reduced emissions.

Examination of Fracture Interfaces in Silicon Nitride

1975 ◽  
Vol 33 ◽  
pp. 60-61
Author(s):  
Nancy J. Tighe
Keyword(s):  
Silicon Nitride ◽  
Grain Boundary ◽  
Crack Growth ◽  
Subcritical Crack Growth ◽  
Slow Crack Growth ◽  
Ceramic Materials ◽  
Grain Boundary Sliding ◽  
Boundary Phase ◽  
Turbine Engines ◽  
Boundary Sliding

Silicon nitride is one of the ceramic materials being considered for the components in gas turbine engines which will be exposed to temperatures of 1000 to 1400°C. Test specimens from hot-pressed billets exhibit flexural strengths of approximately 50 MN/m2 at 1000°C. However, the strength degrades rapidly to less than 20 MN/m2 at 1400°C. The strength degradition is attributed to subcritical crack growth phenomena evidenced by a stress rate dependence of the flexural strength and the stress intensity factor. This phenomena is termed slow crack growth and is associated with the onset of plastic deformation at the crack tip. Lange attributed the subcritical crack growth tb a glassy silicate grain boundary phase which decreased in viscosity with increased temperature and permitted a form of grain boundary sliding to occur.

Layer thickness optimization of ceramic composite for body armor by considering volume, weight, and cost

2021 ◽  
pp. 095440622110157
Author(s):  
Yuksel Palaci ◽  
Mustafa M Arikan
Keyword(s):  
Silicon Nitride ◽  
Boron Carbide ◽  
Layer Thickness ◽  
Ceramic Composite ◽  
Material Selection ◽  
Composite Layer ◽  
Ceramic Materials ◽  
Ternary Diagram ◽  
Body Armor ◽  
Volume Weight

This study investigates visualization of optimized layer thickness with a ternary diagram by considering Volume, Weight, and Cost priorities to determine the composite structure of alternative ceramics to use in body armor application by using the Digital Logic Method (DLM). Three criterion priorities (volume, weight, cost) have been investigated to help designers decide on optimum ceramic material for their applications. Alumina (Al2O3), silicon carbide (SiC), silicon nitride (Si3N4), and boron carbide (B4C) were analyzed and ranked to decide for material selection based on priorities. The analysis results showed that silicon nitride (Si3N4) had the maximum performance index (PI) point (80.0) based on the volume priority. On the other hand, while boron carbide (B4C) had the maximum PI point (76.4) in terms of the weight priority, alumina (Al2O3) was determined to be the best material according to the cost priority. PI point of alumina (Al2O3) was calculated as 100. A ternary diagram was developed for decision-makers to visualize material selection performances. The optimization of the ceramic composite layer thickness of the alternative ceramic materials is visualized by considering three criteria.

scholarly journals Feasibility of a Helium Closed-Cycle Gas Turbine for UAV Propulsion

2020 ◽  
Vol 11 (1) ◽  
pp. 28
Author(s):  
Emmanuel O. Osigwe ◽  
Arnold Gad-Briggs ◽  
Theoklis Nikolaidis
Keyword(s):  
Gas Turbine ◽  
Gas Turbines ◽  
Pressure Ratio ◽  
Low Noise ◽  
Closed Cycle ◽  
Propulsion Systems ◽  
Component Design ◽  
Readiness Level ◽  
Aerial Vehicle ◽  
Turbine Design

When selecting a design for an unmanned aerial vehicle, the choice of the propulsion system is vital in terms of mission requirements, sustainability, usability, noise, controllability, reliability and technology readiness level (TRL). This study analyses the various propulsion systems used in unmanned aerial vehicles (UAVs), paying particular focus on the closed-cycle propulsion systems. The study also investigates the feasibility of using helium closed-cycle gas turbines for UAV propulsion, highlighting the merits and demerits of helium closed-cycle gas turbines. Some of the advantages mentioned include high payload, low noise and high altitude mission ability; while the major drawbacks include a heat sink, nuclear hazard radiation and the shield weight. A preliminary assessment of the cycle showed that a pressure ratio of 4, turbine entry temperature (TET) of 800 °C and mass flow of 50 kg/s could be used to achieve a lightweight helium closed-cycle gas turbine design for UAV mission considering component design constraints.

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