Experimental determination of stator endwall heat transfer

Local Stanton numbers were experimentally determined for the endwall surface of a turbine vane passage. A six vane linear cascade having vanes with an axial chord of 13.81 cm was used. Results were obtained for Reynolds numbers based on inlet velocity and axial chord between 73,000 and 495,000. The test section was connected to a low pressure exhaust system. Ambient air was drawn into the test section, inlet velocity was controlled up to a maximum of 59.4 m/sec. The effect of the inlet boundary layer thickness on the endwall heat transfer was determined for a range of test section flow rates. The liquid crystal measurement technique was used to measure heat transfer. Endwall heat transfer was determined by applying electrical power to a foil heater attached to the cascade endwall. The temperature at which the liquid crystal exhibited a specific color was known from a calibration test. Lines showing this specific color were isotherms, and because of uniform heat generation they were also lines of nearly constant heat transfer. Endwall static pressures were measured, along with surveys of total pressure and flow angles at the inlet and exit of the cascade

High-resolution liquid-crystal heat-transfer measurements on the end wall of a turbine passage with variations in Reynolds number

Local heat-transfer coefficients were experimentally mapped on the end-wall surface of a three-times turbine vane passage in a static, single-row cascade operated with room-temperature inlet air over a range of Reynolds numbers. The test surface was a composite of commercially available materials: a Mylar sheet with a layer of cholesteric liquid crystals, which change color with temperature, and a heater made of a polyester sheet coated with vapor-deposited gold, which produces uniform heat flux. After the initial selection and calibration of the composite sheet, accurate, quantitative, and continuous heat-transfer coefficients were mapped over the end-wall surface. The local heat-transfer coefficients (expressed as nondimensional Stanton number) are presented for inlet Reynolds numbers (based on vane axial chord) from 0.83 x 10(5) to 3.97 x 10(5)

Visualization techniques to experimentally model flow and heat transfer in turbine and aircraft flow passages

Increased attention to fuel economy and increased thrust requirements have increased the demand for higher aircraft gas turbine engine efficiency through the use of higher turbine inlet temperatures. These higher temperatures increase the importance of understanding the heat transfer patterns which occur throughout the turbine passages. It is often necessary to use a special coating or some form of cooling to maintain metal temperatures at a level which the metal can withstand for long periods of time. Effective cooling schemes can result in significant fuel savings through higher allowable turbine inlet temperatures and can increase engine life. Before proceeding with the development of any new turbine it is economically desirable to create both mathematical and experimental models to study and predict flow characteristics and temperature distributions. Some of the methods are described used to physically model heat transfer patterns, cooling schemes, and other complex flow patterns associated with turbine and aircraft passages

Episodic neurologic disorders: syndromes, genes, and mechanisms.

Many neurologic diseases cause discrete episodic impairment in contrast with progressive deterioration. The symptoms of these episodic disorders exhibit striking variety. Herein we review what is known of the phenotypes, genetics, and pathophysiology of episodic neurologic disorders. Of these, most are genetically complex, with unknown or polygenic inheritance. In contrast, a fascinating panoply of episodic disorders exhibit Mendelian inheritance. We classify episodic Mendelian disorders according to the primary neuroanatomical location affected: skeletal muscle, cardiac muscle, neuromuscular junction, peripheral nerve, or central nervous system (CNS). Most known Mendelian mutations alter genes that encode membrane-bound ion channels. These mutations cause ion channel dysfunction, which ultimately leads to altered membrane excitability as manifested by episodic disease. Other Mendelian disease genes encode proteins essential for ion channel trafficking or stability. These observations have cemented the channelopathy paradigm, in which episodic disorders are conceptualized as disorders of ion channels. However, we expand on this paradigm to propose that dysfunction at the synaptic and neuronal circuit levels may underlie some episodic neurologic entities

Selected biological characteristics of Brachymeria ovata reared on live and freezer-stored pupae of the cabbage looper, Trichoplusia ni

Parasitoids can be an important part of a biological control program. The use of freezer-stored pupae has been suggested as a means to rear large numbers of parasitoids for release in biological control programs (Grant and Shepard 1987). Brachymeria ovata (Say) (Hymenoptera: Chalcididae) has been reared successfully from freezer-stored pupae of several noctuid species of lepidoptera (Grant and Shepard 1987); however, it was not known if the use of freezer-stored pupae as hosts of B. ovata had any affect on the biological characteristics of this parasitoid. A colony of B. ovata was maintained, and all experiments were conducted, utilizing the pupae of the cabbage looper, Trichoplusia ni (Hübner) (Lepidoptera: Noctuidae). Experiments were conducted at 27±2°C and 50 to 65%RH. The mating ability of individuals reared from freezer-stored pupae was not significantly impacted; however, a slight decrease in successful matings was observed when males were reared from freezer-stored pupae. The mean preovipositional period increased when individuals were reared from freezer-stored pupae. B. ovata generally parasitized pupae during the hours of light. The greatest number of parasitoids were produced during the first four-hour period of light and the number of progeny produced decreased throughout the day. Unmated female B. ovata individuals not exposed to hosts generally lived longer (114.0 and 135.8 days, respectively, when reared from live and freezerstored pupae) than unmated males (approximately 100 days), and those females reared from freezer-stored pupae lived significantly longer than females reared from live pupae. Paired adults lived for shorter periods than unmated B. ovata. Longevity of paired females exposed to live pupae was significantly shorter (approximately 15 days) than the longevity of males or females not exposed to live or freezer-stored pupae (approximately 60 to 86 days, respectively). Fecundity of B. ovata increased when females were exposed to freezerstored pupae. Those females reared on and exposed to freezer-stored pupae produced the greatest number of eggs (x =422.2). Females exposed to live pupae lived one fourth to one third as long when reared from live or freezerstored pupae, respectively, and produced an average of 91.3 and 137.2 eggs, respectively. Progeny production was significantly decreased when females were exposed to freezer-stored pupae. Females produced an average of 83.3 and 79.1 progeny when reared from live or freezer-stored pupae, respectively, and exposed to live pupae during their entire lifetime. Females exposed to freezerstored pupae produced significantly fewer progeny (x=31.9 and 37.3, respectively, when reared from live or freezer-stored pupae) during the first 14 days of oviposition. As the fecundity of individuals exposed to freezer-stored pupae is greater than that of ones exposed to live pupae, the potential exists for greater progeny production from females exposed to freezer-stored pupae. The acceptability of freezer-stored pupae was significantly lower than that of live pupae in terms of the percentage of pupae containing eggs (88.2% of live pupae and 71.4% of freezer-stored pupae) but the average number of eggs per pupa was not significantly different. The suitability of live and freezer-stored pupae in terms of the percentage of pupae supporting development of B. ovata to adulthood was significantly higher for live pupae (85.5%) than for freezer-stored pupae (23.0%) Higher levels of suitability were observed in other experiments utilizing freezer-stored pupae. The suitability of different age pupae, at time of freezing, and of live pupae also, was determined to be from two to five days after pupation. Many individuals reared on older pupae were smaller than those reared on pupae two to five days old. The production of small adults was probably a result of having less food available to the larva. The development of immature stages of B. ovata in freezer-stored pupae was lengthened from two to five days in the larval stage and about one day in the pupal stage. Overall freezer-stored pupae did not detrimentally impact upon the biological characteristics of B. ovata. With increased suitability of freezer-stored pupae as observed in some experiments conducted in this study as well as others (Grant and Shepard 1987), it should be economically advantageous to use freezer-stored pupae as a host for B. ovata

A Comparative Study Of Creativity In Comprehensive And Continuation High School Students, Grades Eleven And Twelve.

It was the purpose of this study to investigate and compare relationships which exist between the tested creative behavior or eleventh and twelfth grade continuation high school students and their counterparts in a comprehensive high school. Creativity scores were obtained for each of three ranked IQ groups of students tested at each of the two participating schools. Creativity scores were obtained for each of the four creative ability factors, Fluency, Flexibility, Originality, and Elaboration as measured by the Torrance Tests of Creative Thinking, Figural--B

Characterization of a missle flyout simulation

This thesis develops a systematic approach to exploring the response of a missile flyout software simulation to input noise. The research is intended to augment the current characterization tests employed by the Electronic Warfare Testing community. This thesis explores the direct relationship between specific input noise signals and individual simulation responses. The design defines an approach for characterizing the behavior of a deterministic simulation of tremendous complexity by controlling test conditions. Techniques for generating realistic random noise are derived. A statistical model of the relationship between input noise missile miss distance at the point of closest approach is presented. The statistical model coefficients are tested for validity. The techniques used are of general applicability to future missile simulation studies

Use of a liquid-crystal, heater-element composite for quantitative, high-resolution heat transfer coefficients on a turbine airfoil, including turbulence and surface roughness effects

Local heat transfer coefficients were measured along the midchord of a three-times-size turbine vane airfoil in a static cascade operated at roon temperature over a range of Reynolds numbers. The test surface consisted of a composite of commercially available materials: a Mylar sheet with a layer of cholestric liquid crystals, which change color with temperature, and a heater made of a polyester sheet coated with vapor-deposited gold, which produces uniform heat flux. After the initial selection and calibration of the composite sheet, accurate, quantitative, and continuous heat transfer coefficients were mapped over the airfoil surface. Tests were conducted at two free-stream turbulence intensities: 0.6 percent, which is typical of wind tunnels; and 10 percent, which is typical of real engine conditions. In addition to a smooth airfoil, the effects of local leading-edge sand roughness were also examined for a value greater than the critical roughness. The local heat transfer coefficients are presented for both free-stream turbulence intensities for inlet Reynolds numbers from 1.20 to 5.55 x 10 to the 5th power. Comparisons are also made with analytical values of heat transfer coefficients obtained from the STAN5 boundary layer code

The Effect of Processing Parameters on Barrier Properties of Polymers

The intent of this work was to learn if polyethylene could be made with predictable water transfer rates by control of the microstructure. A series of films were formed from three different polyethylenes with a range crystallinities using melt pressing, a controlled cooling rate, and subsequent heat treatments. The samples were tested on a novel device called the polymer characterization device that measures the water transfer flux as a function of temperature. The samples’ morphology was examined using differential gradient column, differential scanning calorimetry, Fourier transform infrared microscopy, wide-angle X-ray diffractions, small-angle X-ray scattering, and small angle light scattering, and scanning electron microscopy. When the water transfer flux was expressed as the frost point of a dry carrier gas the results showed a remarkable sensitivity that allows for analysis of subtle distinction in rates due to changes in morphology. Analysis showed that the water transfer flux is a function of the polymer, conditions of the samples preparation from the melt, and any subsequent heat treatment. Another interesting finding was that the time for the sample to reach a steady state water transfer flux is a function of morphology. A free volume model was developed to that simulates the response of the polymer as a function of morphology, presence of water, and thermal cycling. The conclusion of this work is that the water transfer flux is a function of the specific polymer, the initial formation conditions, and later heat treatments and with this knowledge the polymer could be made with a specific water transfer flux