Small gas-turbine combustor study: Fuel injector evaluation

As part of a continuing effort at the Lewis Research Center to improve performance, emissions, and reliability of turbine machinery, an investigation of fuel injection technique and effect of fuel type on small gas turbine combustors was undertaken. Performance and pollutant emission levels are documented over a range of simulated flight conditions for a reverse flow combustor configuration using simplex pressure-atomizing, spill-flow return, and splash cone airblast injectors. A parametric evaluation of the effect of increased combustor loading with each of the fuel injector types was obtained. Jet A and an experimental referee broad specification fuel were used to determine the effect of fuel type

Advanced liner-cooling techniques for gas turbine combustors

Component research for advanced small gas turbine engines is currently underway at the NASA Lewis Research Center. As part of this program, a basic reverse-flow combustor geometry was being maintained while different advanced liner wall cooling techniques were investigated. Performance and liner cooling effectiveness of the experimental combustor configuration featuring counter-flow film-cooled panels is presented and compared with two previously reported combustors featuring: splash film-cooled liner walls; and transpiration cooled liner walls (Lamilloy)

Small gas turbine combustor study: Fuel injector performance in a transpiration-cooled liner

The effect of fuel injection technique on the performance of an advanced reverse flow combustor liner constructed of Lamilloy (a multilaminate transpiration type material) was determined. Performance and emission levels are documented over a range of simulated flight conditions using simplex pressure atomizing, spill return, and splash cone airblast injectors. A parametric evaluation of the effect of increased combustor loading with each of the fuel injector types is obtained

Small gas turbine combustor study: Combustor liner evaluation

For abstract see A83-16663

Effect of broad properties fuel on injector performance in a reverse flow combustor

The effect of fuel type on the performance of various fuel injectors was investigated in a reverse flow combustor. Combustor performance and emissions are documented for simplex pressure atomizing, spill flow, and airblast fuel injectors using a broad properties fuel and compared with performance using Jet A fuel. Test conditions simulated a range of flight conditions including sea level take off, low and high altitude cruise, as well as a parametric evaluation of the effect of increased combustor loading. The baseline simplex injector produced higher emission levels with corresponding lower combustion efficiency with the broad properties fuel. There was little or not loss in performance by the two advanced concept injectors with the broad properties fuel. The airblast injector proved to be especially insensitive to fuel type

Effect of fuel injector type on performance and emissions of reverse-flow combustor

The combustion process in a reverse-flow combustor suitable for a small gas turbine engine was investigated to evaluate the effect of fuel injector type on performance and emissions. Fuel injector configurations using pressure-atomizing, spill-flow, air blast, and air-assist techniques were compared and evaluated on the basis of performance obtained in a full-scale experimental combustor operated at inlet conditions corresponding to takeoff, cruise, low power, and idle and typical of a 16:1-pressure-ratio turbine engine. Major differences in combustor performance and emissions characteristics were experienced with each injector type even though the aerodynamic configuration was common to most combustor models. Performance characteristics obtained with the various fuel injector types could not have been predicted from bench-test injector spray characteristics. The effect of the number of operating fuel injectors on performance and emissions is also presented

Reverse-flow combustor for small gas turbines with pressure-atomizing fuel injectors

A reverse flow combustor suitable for a small gas turbine (2 to 3 kg/s mass flow) was used to evalute the effect of pressure atomizing fuel injectors on combustor performance. In these tests an experimental combustor was designed to operate with 18 simplex pressure atomizing fuel injectors at sea level takeoff conditions. To improve performance at low power conditions, fuel was redistributed so that only every other injector was operational. Combustor performance, emissions, and liner temperature were compared over a range of pressure and inlet air temperatures corresponding to simulated idle, cruise, and takeoff conditions typical of a 16 to 1 pressure ratio turbine engine

Reticuloendothelial System Function Following Acute Liver Failure Induced by 90% Hepatectomy in the Rat

Sepsis and bacterial infections are frequent complications of acute liver failure and following major liver resection. The mechanisms underlying this phenomenon are unclear. In this study, RES function and blood clearance of radiolabelled E. coli was immediately impaired following 90% hepatectomy, although the reduction in liver volume resulted in an increase in splenic (temporary) and pulmonary (persisting) uptake. A significant correlation between liver function and host RES function was observed. The uptake capacity of the RES in the liver remnant and spleen did not correlate with subserosal blood flow. The uptake in the brain gradually increased with time, paralleling an increased leakage across the blood-brain barrier. Thus, a significantly impaired RES function resulted from experimental 90% hepatectomy-induced acute liver failure, which might explain the high incidence of septic events in the clinical situation

Calculated and experimental Schmid factors for chip flow deformation of textured CVD α-alumina coatings

A thorough analysis of Schmid factors (m) for three different (basal and two prismatic) slip systems and three different coating textures, (0001), (011\uaf2) and (112\uaf0), was done in order to understand the influence of CVD α-alumina coating textures on the ability of the coatings to deform plastically at different locations on the rake face of a cutting tool insert during a metal machining operation. Schmid factor diagrams were constructed using MATLAB/MTEX in order to visualize the angular dependence of an external force relative to the α-Al O crystals (grains) on the Schmid factor. The diagrams were also used to extract m-value frequency distributions for different slip systems and textures. In addition, lateral m-value distribution maps were obtained from experimental textured coatings using electron backscatter diffraction. These maps show the ability for neighboring grains to deform plastically in the coatings. Cutting tool inserts with differently textured α-Al2O3 coatings were subjected to dry machining of a quench-tempered steel. Using scanning electron microscopy, the microstructure and surface topography of the worn alumina layers were investigated and it was found that a flatter surface morphology and higher probability of discrete plastic deformation are connected to less wear. This was observed in the (0001)-textured sample, which also exhibited the highest m-values in the wear zone with highest temperatures and external forces. It was observed that basal slip is most easily activated, followed by prismatic slip systems 1 and 2 in this case. For (011\uaf2) and (112\uaf0) textured coatings the differences in m-values for the three slip systems are not that big, and the distributions are relatively wide. It is clear that the Schmid factor analysis forms a basis that is important for understanding crater wear, especially when it is connected to local plastic deformation, of textured CVD α-Al2O3 coatings. The methodology of this work can be expanded to other coating systems and also more generally to applications where it is of interest to analyze the deformation behavior and local plastic anisotropy of textured materials

Posterior interosseous nerve localization within the proximal forearm - a patient normalized parameter

AIM To provide a “patient-normalized” parameter in the proximal forearm. METHODS Sixty-three cadaveric upper extremities from thirty-five cadavers were studied. A muscle splitting approach was utilized to locate the posterior interosseous nerve (PIN) at the point where it emerges from beneath the supinator. The supinator was carefully incised to expose the midpoint length of the nerve as it passes into the forearm while preserving the associated fascial connections, thereby preserving the relationship of the nerve with the muscle. We measured the transepicondylar distance (TED), PIN distance in the forearm’s neutral rotation position, pronation position, supination position, and the nerve width. Two individuals performed measurements using a digital caliper with inter-observer and intra-observer blinding. The results were analyzed with the Wilcoxon-Mann-Whitney test for paired samples. RESULTS In pronation, the PIN was within two confidence intervals of 1.0 TED in 95% of cases (range 0.7-1.3 TED); in neutral, within two confidence intervals of 0.84 TED in 95% of cases (range 0.5-1.1 TED); in supination, within two confidence intervals of 0.72 TED in 95% of cases (range 0.5-0.9 TED). The mean PIN distance from the lateral epicondyle was 100% of TED in a pronated forearm, 84% in neutral, and 72% in supination. Predictive accuracy was highest in supination; in all cases the majority of specimens (90.47%-95.23%) are within 2 cm of the forearm position-specific percentage of TED. When comparing right to left sides for TEDs with the signed Wilcoxon-Mann-Whitney test for paired samples as well as a significance test (with normal distribution), the P-value was 0.0357 (significance - 0.05) indicating a significant difference between the two sides. CONCLUSION This “patient normalized” parameter localizes the PIN crossing a line drawn between the lateral epicondyle and the radial styloid. Accurate PIN localization will aid in diagnosis, injections, and surgical approaches