There is an increasing dependence on conventional fuels for aviation. In order for a country’s air force to sustain a steady and a secure supply of fuel for aircraft with foresight into the future, alternate sources of fuels must be considered. This paper describes a thermodynamic performance simulation method and analysis of a model military aero gas turbine engine operating in several off-design modes while employing various types of blended fuels between Jet A and alternate bio-fuels, including Synthetic Paraffinic Kerosene (SPK) from Algae (Bio-Algae), Jatropha (JSPK) and Camelina (CSPK). These fuels are already approved by American Society for Testing and Materials (AS™) for blending with 50% Jet A fuel. A thermodynamic performance model for the model engine similar to GE F404-400 turbofan engine has been set up using Pythia, a Cranfield University created performance simulation software implemented with multiple fuel capabilities. The simulated performance and a comparative study shows that the performance of the model engine using blended fuels between Jet A and a bio-fuel were found to be equal or better than that using pure conventional fuel Jet A. The key hot section temperatures, pressures and the fuel consumption of the model engine were found to be slightly lower with the blended fuels than that using Jet A.

Thermal stability is an important characteristic of alternative fuels that must be evaluated before they can be used in aviation engines. This characteristic is of great importance to the effectiveness of the fuel as a coolant and to the engine’s combustion performance. In this work, the thermal stability of Gevo fuel, an alcohol to jet fuel made from plant derived feedstock, was studied. This analysis was used to comment on the effectiveness of the current thermal stability test standard. This work was performed using a spectroscopic ellipsometer to measure the thickness of deposits left on aluminum substrates. It was observed that Gevo deposit thickness increased slowly up to 375 °C and much more rapidly after that point. Similar behavior was observed in JP-8 fuel. Comparisons were also made between color standard ratings and ellipsometric thickness measurements, and it was found that in some cases, darker colors did not indicate thicker deposits. Reference tubes were used to validate the optical models used in this work, and different optical constants were found to best model the results than what are published in the ASTM D3241 test method for thermal stability.

The National Jet Fuel Combustion Program (NJFCP) is an initiative, currently being led by the Office of Environment & Energy at the FAA, to streamline the ASTM jet fuels certification process for alternative aviation fuels. In order to accomplish this objective, the program has identified specific applied research tasks in several areas. The National Research Council of Canada (NRC) is contributing to the NJFCP in the areas of sprays and atomization and high altitude engine performance. This paper describes work pertaining to atomization tests using a reference injection system. The work involves characterization of the injection nozzle, comparison of sprays and atomization quality of various conventional and alternative fuels, as well as use of the experimental data to validate spray correlations. The paper also briefly explores the application viability of a new spray diagnostic system that has potential to reduce test time in characterizing sprays. Measurements were made from ambient up to 10 bar pressures in NRC’s High Pressure Spray Facility using optical diagnostics including laser diffraction, phase Doppler anemometry (PDA), LIF/Mie Imaging and laser sheet imaging to assess differences in the atomization characteristics of the test fuels. A total of nine test fluids including six NJFCP fuels and three calibration fluids were used. The experimental data was then used to validate semi-empirical models, developed through years of experience by engine OEMs and modified under NJFCP, for predicting droplet size and distribution. The work offers effective tools for developing advanced fuel injectors, and generating data that can be used to significantly enhance multi-dimensional combustor simulation capabilities.

Elevated pressure and temperature conditions are widely encountered during gas turbine operation. To avoid unexpected ignition and explosion of mixtures of fuel and air under these conditions, it is imperative to identify the flammability limits of relevant fuel mixtures. Common fuels include process gases such as natural gas, coke oven gas and IGCC syngas fuel. The flammability limits of pure fuels and common gas/air mixtures have been widely reported, however a significant lack of flammability data for fuel mixtures relevant for use in gas turbines as well as data at elevated pressure and temperature conditions is available. The objective of this study is to characterize the flammability limits of fuel/air mixtures and their dependence on initial temperature and pressure. Experimental studies of lean flammability limits (LFLs) for methane, hydrogen, and carbon monoxide, in addition to mixtures of these gases (i.e. CH 4 /H 2 , H 2 /CO, and CH 4 /CO 2 ) were performed at temperatures up to 200 °C and pressures up to 9 bar. ASTM Standard E918 (1983) provided the framework for tests using a one-liter pressure-rated test cylinder in which the fuel-air mixtures were prepared and then ignited. Flammability is determined using a 7% and 5% pressure rise criterion per the ASTM E918 and European EN 1839 standards, respectively. The LFLs for each gas and gas mixture are found to decrease linearly with increasing temperature for the temperature range tested. The LFLs of hydrogen and mixtures containing hydrogen are observed to increase with an increase in the initial pressure, whereas the LFLs of all other mixtures exhibit a negligible dependence on pressure. For mixtures, predicted LFL values obtained using Le Chatelier’s mixing rule (LC) are fairly consistent with the experimentally determined values near ambient conditions, however it is not recommended for use at elevated pressure and/or temperature. Finally, the experimental data presented in this study are compared with previous experimental studies, flammability limits calculated using numerical methods, and past studies of predicted LFL values for similar fuel/air mixtures. The purpose for characterizing the flammability limits for these gaseous mixtures is to extend the results to developing appropriate procedures for the safe industrial use of renewable gases, such as bio-derived methane, biogas composed mainly of methane and carbon dioxide, and renewably derived syngas which contains large quantities of hydrogen and carbon monoxide gas.

Ceramic matrix composite (CMC) materials are targeted for high temperature application in aircraft and power turbines, because of their low density and high-temperature thermo-mechanical properties, compared to conventional nickel super alloys. New test methods are needed for the assessment of the effects of delamination cracks on the structural integrity and life of CMC components. The ASTM C28 Fracture Toughness (Crack Growth Resistance – CGR) Working Group has drafted a standard test method for the “Mode I Interlaminar Fracture Tougness (G Ic – Crack Growth Resistance) of Fiber-Reinforced Ceramic Matrix Composites (CMC) by Wedge Loading of a Double Cantilever Beam at Ambient Temperatures” The wedge loading method was developed to avoid the problems of high temperature bonding of loading blocks and hinges. The ASTM test standard details the scope, use, and application of the test method, interferences, test equipment, specimen geometry and preparation, test procedures, data interpretation and calculation, and reporting requirements for the new CMC CGR test method.

Extrusion additive manufacturing technologies may be utilized to fabricate complex geometry devices to control the flow distortions at the inlets of gas turbine engines. However, the success of these devices depends upon their ability to withstand the dynamic mechanical loads experienced in service. One such device is a StreamVane ® . A current candidate material for StreamVane fabrication is ULTEM 9085 — a thermoplastic polymer material. ULTEM 9085 was selected as the material of choice for StreamVane production because of its high strength-to-weight ratio. In this study, quasi-static and cyclic fatigue tests were performed on ULTEM 9085 samples fabricated by fused deposition modeling. First, ASTM D638 tensile-tensile material tests were conducted on three different build orientations to verify the mechanical strength of ULTEM 9085 listed by Stratasys. The three different orientations that were tested were Orientation XZZ, Orientation XYZ, and Orientation ZXY with measured ultimate tensile strengths of 69.6 MPa, 56.3 MPa, and 37.6 MPa, respectively. Fatigue properties were investigated utilizing the procedure outlined in ASTM D7791. S-N curves were generated using data collected at stress levels of 80%, 60%, 30% and 20% of the ultimate tensile stress with an R-ratio of 0.1 for the build orientation XZY. Next, the modified Goodman approach was used to estimate the fully reversed (R = −1) fatigue life. The initial data suggested that the modified Goodman approach was very conservative. Therefore, four different stress levels of 25%, 20%, 15% and 10% of ultimate tensile stress were used to characterize the fully reversed fatigue properties. Because of the extreme conservatism of the modified Goodman model for this material, a simple phenomenological model was developed to estimate the fatigue life of ULTEM 9085 subjected to fatigue at different R-ratios. The calculated fatigue life using the model and the data collected for the fully reversed test correlated very well. The data from this investigation demonstrated that StreamVane designs using ULTEM 9085 are more than capable of withstanding the static and dynamic loads in currently planned turbomachinery applications.

Badak LNG Plant Bontang have succeeded in mixing different brands of turbomachinery lube oil ISO VG32 which intended to increase flexibility of lube oil usage and eliminate to one brand dependency during operational. The methodology referred to ASTM D7155 Standard Practice for Evaluating Compatibility of Mixtures of Turbine Lubricating Oils and ASTM D4378 Standard Practice for In-Service Monitoring of Mineral Turbine Oils for Steam, Gas and Combined Cycle Turbines. The study was started from lube oil compatibility test at laboratory. After that, a ratio 70:30 of ISO VG32 existing lube oil (DTE Light) and new lube oil (Turbolube XT32) were mixed and trialed to Fuel Gas Compressor and its Turbine Driver. Lube oil and equipment operating parameter such as viscosity, color, water content, total acid number, foaming tendency, oxidation, metal content, flash point, bearing temperature, filter differential pressure, and vibration were collected and compared to baseline data to analyze deterioration indication of lube oil. As long as eight month trial test, there was no deterioration indication of lube oil mixture and no significant influence to the equipment operating performance. Badak LNG have decided to continue lube oil mixing.

A Durability and Damage Tolerance (D&DT) analysis of an S200 Nicalon/SiNC CVI SiC/SiC attachment joint was conducted to determine the CMC components material structural integrity during service loading. A building block validation strategy is proposed that includes: (i) Room, and High Temperature (RT/HT) testing with AE (Acoustic Emission) and ER (Electrical Resistivity) strategies; (ii) Advanced multi-scale modeling; (iii) Interpretation test/model; and (iv) ASTM draft submittal of simplified beam equation supported by FEM/test compliance and round robin exercise. The following building block calibration, verification, validation, and accreditation strategy were performed: 1 ) Material characterization analysis to determine the damage evolution under uniaxial tensile loads and compared with test; 2 ) Crack Growth Resistance (CGR) analysis and test of wedge loaded DCB (Double Cantilever Beam) to determine the crack growth length, zig-zag pattern, fracture, shift in failure mechanisms and derivation of fracture energy vs. crack length simple formulation at RT; 3 ) Joint loading multi scale modeling and comparison with observed test load displacement curve, and determination of fracture energy; and 4 ) blade structural integrity and response under service loading using Multi-Scale Progressive Failure Analysis (MS-PFA) and determination of contributing damage and delamination types and their locations. FE based MS-PFA of the material and structure studied addressed the critical damage events (damage initiation, damage propagation, fracture initiation, and fracture propagation) as the components were being loaded. All dehomogenized multi scale methods CMC parameters were implemented in the material and structural modeling strategy, such as crack density effects and architecture (2D, 3D orthogonal, and mixed) interphase thickness, and interfacial shear strength. Many parameters that contribute to specimen failure including interface coating thickness, mixed mode failure evolution, interlaminar defects, delamination damage, crack bridging, and fiber fracture were all studied in detail in this work. Several FE-based multi-scale modeling techniques were investigated: a) MS-PFA; b) Virtual Crack Closure Technique (VCCT); and c) integrated damage and fracture evolution methodology using combined MS-PFA and VCCT.

The certification of new fuels for aircraft applications requires preliminary extensive investigations for the most critical combustion phases. Especially, cold start and altitude relight of an aircraft gas turbine and thus its operating envelope could potentially be affected by the use of new fuels. To assess such effects, a test rig is designed using two different air-assist pressure atomizers. The ignition envelopes for seven different blends with a minimum of 50% Jet A-1 are compared to that of pure Jet A-1. Variation in combustor aerodynamics is accounted for by considering various pressure drops across the combustion chamber, and the ignition envelope is retrieved by finding the minimum and maximum fuel-air ratios leading to a successful ignition event. Effects of fuel physical properties, pressure and temperature which are critical factors for a successful ignition event are also investigated. To simulate cold start and altitude relight, a heat exchanger is used to cool air and fuel, while a bleed valve mounted between the combustor and a steam ejector is used to regulate the operating pressure. Globally, cold start for temperatures ranging from 10°C to −40°C, and the altitude relight for operating altitudes ranging from 4 572 m to 10 668 m, show that the lean limit for the seven blends of fuels are in some cases as good as, and for the other cases better than the pure Jet A-1. Some discrepancies are noted for altitude relight at 9 161 m and 10 688 m, for some biofuels with a minimum of 50% Jet A-1, suggesting a need of real engine testing before final approval. Apart from these isolate cases, almost all the biofuel blends with a minimum of 50% Jet A-1 are truly “drop-in” fuels and should qualify for aviation use since they do not present any negative impact on the typical engine components used in the test program. Furthermore, ASTM D1655 requirements are also achieved for all test conditions. Biofuel blends with less than 50% Jet A-1 are found to always be better than the biofuel blends with minimum of 50% Jet A-1 and, it is recommended to modify ASTM D1655 to include them as acceptable “drop-in” fuels.

An investigation of cycling rate effects on fatigue life behavior is being conducted on Aluminum (Al) alloys. This effect, along with specimen diameter, highlights the major difference between ultrasonic and servohydraulic fatigue test procedures. Ultrasonic fatigue testing is conducted on a 3.2 mm diameter hourglass specimen operating at 26 kHz, and servohydraulic axial testing is conducted on an ASTM E 466-07 standard dogbone specimen with a 25.4 mm gage length and 4.45 mm diameter operating at 35 Hz. Previous works have shown that cycling rate increases of 100–1000 times can reduce the fatigue crack growth rates in the stress intensity region between threshold and critical by at least an order of magnitude for aluminum and steel. For high cycle fatigue (HCF), however, where the majority of cycles to failure are accumulated before crack initiation, not during propagation, the effects of cycling rate on total loading cycles to failure needs further understanding, which may lead to more accurate and/or less conservative HCF design of critical gas turbine engine components. Fatigue behavior of Al 6061-T6 was assessed between the failure range of 10 4 –10 10 cycles using ultrasonic and servohydraulic testing procedures. Though aluminum is not a widely used alloy in gas turbine engine applications, understanding frequency-based fatigue life discrepancies associated with the choice of empirical methods is of paramount importance to component design; Aluminum 6061-T6 is the most cost-effective way to gaining this understanding. Comparisons were made between the fatigue behavior results using cycling rate (also stated as strain-rate or frequency) comparisons for fatigue crack growth study. The comparisons show promising results correlating the fatigue behavior trends of servhydraulic and ultrasonic fatigue data.

ASTM test standards for CMC’s Crack Growth Resistance (CGR) may exhibit a zig-zag (wavy) crack path pattern, and fiber bridging. The experimental parameters that may contribute to the difficulty can be summarized as: specimen width and thickness, interface coating thickness, mixed mode failure evolution, and interlaminar defects. Modes I crack growth resistances, G I were analytically determined at ambient temperature using wedge test, a modified double cantilever beam (DCB). Several Finite Element (FE) based Multi-scale modeling potential techniques were investigated: a ) Multi-scale progressive failure analysis (MS-PFA); b ) Virtual Crack Closure Technique (VCCT). Advantages and disadvantages of each were identified. The final modeling algorithm recommended was an integrated damage and fracture evolution methodology using combined MS-PFA and VCCT. The material tested in this study was a slurry-cast melt-infiltrated SiC/SiC composite with Tyranno ZMI fibers (Ube Industries, Kyoto, Japan) and a BN interphase. The fiber architecture consisted of eight plies of balanced 2-D woven five-harness satin. The total fiber volume fraction was about 30% with half of the fibers in the 0° direction and half in the 90° direction. All specimens had a nominal thickness of 4 mm. An alumina wedge with 18° head angle (2 α ) was used. In this method, a splitting force is created by inserting a vertically-moving wedge in a notch causing the arms to separate and forcing an interlaminar crack at the sharpest end of the notch The MS-PFA numerical model predicted the damage and fracture evolution and utilized the GENOA UMAT (User Material Subroutine) for Damage and FEM (Finite Element Model) stress intensity and LEFM (Linear elastic Fracture Model), Cohesive Model for Fracture. The analysis results (Fracture energy vs. crack length, Fracture energy vs. load, Fracture energy vs. crack opening displacement) matched the Mode I coupon tests and revealed the following key findings. Mode I-Wedge specimen exhibits: 1 ) failure mode is due to interlaminar tension (ILT) only in the interface section and a zig-zag pattern observed; 2 ) VCCT crack growth resistance is well matched to the test data; and 3 ) failure mode is a mixed mode behavior of Interlaminar tension (ILT) to interlaminar shear (ILS). The final Wedge test specimen configuration optimization includes the sensitivity of design parameters to CGR: a ) wedge contact coefficient of friction; b ) lever arms thickness, and c ) inclined head angle, distance between the initial crack and wedge tip.

SiC-based ceramic matrix composites (CMC) in turbine engine applications must sustain fatigue residual life after foreign object impacts that might occur in services. Experiments, nondestructive evaluations (NDE), and simulations have illustrated good correlations between impact energy and foreign object damage (FOD) and fatigue life after impact at room and 1200°C temperatures. Flat and curved five-harness satin (5HS) woven CMCs specimens, consisting of Hi-Nicalon Type S (Goodrich) and Hi-Nicalon (Rolls Royce) in MI SiC matrix, were tested and simulated. Tests measured electrical resistivity (ER), acoustic emission (AE), and microscopy. Simulations used a building block validation strategy and the Multi-Scale Progressive Failure Analysis (MS-PFA) method. Simulations complemented experiments in understanding and predicting the damage states, of impact, and fatigue residual strength after impact of CMCs to form a more complete understanding of the damage mechanisms involved in such events. The GENOA software developed by Alpha STAR Corporation [1, 2, 3] is capable of Durability and Damage Tolerance (D&DT), life, and reliability predictions by means of multi-scale progressive failure analysis (damage and fracture evolution). In general, CMCs are modeled using effective fiber, matrix, and interface constitutive behaviors, from which the lamina stiffness, strengths, and the strain rate effect can be derived. Similarly, the fatigue strength and stiffness degradation, and the effect of defects in a matrix micro crack density, voids, as well as fibers waviness, and damages after impact can be characterized. The final simulation is static loading and impact on a generic CMC SiC/SiC (Sylramic MI 5HS) blade which is to be used in future blade optimization based on minimizing damage incurred. The GENOA software platform supports FAA recommended ASTM standard Building-Block Validation Strategy with reduced tests conducting: 1) Material Calibration and Qualification, and 2) FEM Verification, Validation, and 3) Blind Predictions (Accreditation). The simulation and test comparisons performed included the damage size for both the CMC (fracture) and the steel impactor (plastic deformation), rebound velocities, SN curves for fatigue of pristine and impacted specimens at room and high temperatures. All simulations showed good correlation. The MS-PFA tool demonstrated a great potential for CMC post FOD fatigue life for part certification supported with reduced tests.

The objective of this effort is to develop and demonstrate innovative interlaminar Mode I and Mode II fracture toughness analysis and test methods for ceramic matrix composites (CMC). Currently, there are number of American Society for Testing and Materials (ASTM) test standards for CMC’s at both ambient and elevated temperatures, including interlaminar tension and shear strength test methods. However, there are no standardized test methods for determination of interlaminar fracture toughness in CMC’s. Although research work exists on interlaminar Mode I and Mode II fracture toughness of various types of CMC’s, the test methods applied particularly in Mode II fracture toughness testing showed definite drawbacks and limitations. ASTM test standards for CMC’s may exhibit a zig-zag (wavy) crack path pattern, and fiber bridging. The experimental parameters that may contribute to the difficulty can be summarized as: specimen width and thickness, interface coating thickness, mixed mode failure evolution, and interlaminar defects. Modes I and II crack growth resistances, G I and G II , were analytically determined at ambient temperature using double cantilever beam (DCB) and End Notched Flexure (ENF) geometries. Three (3) CMC material systems were analyzed (Sylramic/IBN/MI, SiC/SiC CVI, and SiC/CAS). Several Finite Element (FE) based potential techniques were investigated: a) Multi-scale progressive failure analysis (MS-PFA); b) Virtual Crack Closure Technique (VCCT); and c) Contour Integral (CI). Advantages and disadvantages of each were identified. The final modeling algorithm recommended was an integrated damage and fracture evolution methodology using MS-PFA and VCCT. The analysis results ( Fracture energy vs. crack length, Fracture energy vs. load, Fracture energy vs. crack opening displacement) matched the Mode I and Mode II coupon tests and revealed the following key findings. Mode I-DCB specimen: 1) Sylramic/IBN/MI failure mode is due to interlaminar tension (ILT) only in the interface section and a zig-zag pattern observed 2) VCCT crack growth resistance of Sylramic/IBN/MI is well matched to the test data and 3) SiC/SiC CVI failure mode is a mixed mode behavior (ILT to interlaminar shear (ILS). Mode II ENF specimen MS-PFA analysis suggests mixed mode behavior and the zig-zag pattern similar to Mode I coupon tests.

The majority of fatigue crack growth tests worldwide makes use of the compact tension (CT) specimens that are not necessarily representative of cracks developing under service conditions in highly stressed components of a jet engine. Over the years other geometries have been designed to facilitate a study of relatively small, semi- or quarter-elliptically shaped surface flaws subjected to high tensile and compressive stresses. Despite an extensive use by the aerospace community, practical aspects of testing and data analysis relevant to the complex surface- or corner-flawed geometries are not regulated by a commonly accepted set of rules. Two types of test specimens — CT and surface-crack tension (SCT) — were machined from a forged and heat treated Inconel 718. For both geometries the crack orientation and propagation direction with respect to the original forging were the same. The CT specimens were tested in accordance with the ASTM Standard E647 as well as using an alternative compression pre-cracking procedure. After correct application of the compression pre-cracking to the CT geometry both approaches had yielded reasonably consistent results. At high ΔK values both studied geometries also produced similar results, however, as the ΔK values decreased, a trend towards slower crack growth rates in the SCT specimens became evident. In order to address a so-called small-crack effect, several SCT specimens received much smaller crack starter notches produced by the focused ion beam (FIB) technology. The results of the present study highlight the importance of the appropriate material properties for accurate and reliable service life prediction of the critical aerospace propulsion hardware with particular emphasis on the influence of specimen/crack geometry and test method on the fatigue crack propagation behavior of jet engine alloys.

The current proposed ASTM GT fuel oil specifications for gas turbines imposes certain limits on contaminants. This paper presents some operating experiences with two gas turbines using a fuel oil that approaches these maximum limits for vanadium and sodium for the proposed Nos. 1, 2, and 3 GT fuels. One year’s satisfactory operation was achieved although evidence of minor corrosion was present, but insufficient to cause replacement of components.

A compact engine configuration is obtained on small gas turbine engines by the use of a reverse flow annular combustion system. Such combustion systems are usually of narrow width and of relatively large flame tube surface area/volume ratio. In consequence, there is a tendency for excessive concentrations of fuel near to the flame tube internal surfaces and fuel impingement on the flame tube which can give rise to performance deficiencies, such as carbon build, loss of efficiency at low load conditions, smoke, and metal overheating particularly with fuels similar to ASTM D 975 Type 2-D diesel. Since there is an increasing requirement for engines to operate with such heavier fuels, research and development programs were initiated to evolve an improved combustion system. The paper briefly describes the main features of these work programs and outlines the configuration evolved and the performance achieved. An arrangement has been obtained which gives a high standard of performance with fuels ranging from aviation kerosene fuel to gas oil and marine diesel.

The measurement of air pollutants emitted to the atmosphere in exhaust gases from stationary gas turbines must be made in accordance with applicable government specifications in those cases where the measurements are being made to determine compliance with regulations. This paper reviews the methods for measuring opacity, sulfur dioxide, oxides of nitrogen, carbon monoxide, carbon dioxide, oxygen, hydrocarbons, and particulates. In addition, the paper references the Federal Register (volume, number, and page) in which the official specification appears. Other methods, including ASME, SAE, and ASTM, are listed where applicable.

Soot samples were extracted from a swirl-stabilized, liquid-fuel fired laboratory combustor to (i) assess the validity of the ASTM smoke point test in predicting the sooting characteristics of fuels in complex combustion systems and (ii) assess the effect of fuel molecular structure and smoke suppressant additives on the physical and chemical properties of soot. Fuels utilized were shale JP-8, isooctane, and blends of isooctane with either decalin, toluene, tetralin, or 1-methylnapthalene such that smoke points similar to JP-8 were achieved. Each fuel was separately blended with 0.05 percent (by weight) ferrocene smoke suppressant. The results indicate that the ASTM test can be misleading, increased fuel molecular complexity increases soot content of higher molecular weight polycyclic aromatics, and ferrocene additive reduces small particle number density but not necessarily the soot mass loading.

Turbine compressor coatings are evaluated for use in acidified environments. In such environments, field performance shows poor correlation to results of neutral salt spray tests (ASTM B117). Tests which might better describe these low pH atmospheres are described and the copper accelerated acetic acid salt spray (ASTM B368) is selected as the most useful development tool. In addition, combining CASS exposure with thermal cycling is shown to be a useful procedure to further differentiate coatings for use in acidic environments. It is shown that, unlike the neutral salt spray, in CASS, highly sacrificial (i.e., galvanic) aluminum-filled ceramic overlay coatings fail more rapidly than do non sacrificial materials. Conventional barrier films represented by high performance polymeric coatings are prone to severe blistering in these acidic conditions. Preferred acid resistant coatings are described.

A series of computations have been made using the gas property computational schemes of Gordon and McBride to compute the gas properties and species concentration of ASTM-Jet A and dry air. The purpose of this work was to present the computed gas thermodynamic properties in a revised graphical format that would present this information in a way very useful to combustion engineers. The plan is to publish an extensive series of reports covering the properties of many fuel and air combinations. The revised graphical presentation displays on one chart the output from hundreds of computer sheets. The published reports will contain microfiche cards, from which complete tables and graphs can be obtained. This report documents the extent of the planned effort and provides samples of the many tables and charts that will be available on the microfiche cards.