Jet Propellant Research Articles

A Prototype of a Biomimetic Mantle Jet Propeller Inspired by Cuttlefish Actuated by SMA Wires and a Theoretical Model for Its Jet Thrust

The cuttlefish have higher swimming speed and more maneuverability than most of the fish mainly benefiting from their unique jet propulsion mechanism, which is realized by the contraction and expansion of their flexible mantle. However it is difficult to mimic this jet propulsion mechanism using conventional electro-mechanical structures. In this paper, the musculature of the cuttlefish mantle and how the mantle flexibly contracts and expands were analyzed first. Then the Shape Memory Alloy(SMA) wires were chosen as the actuators and the soft silica gel was chosen as the body materials to develop a biomimetic mantle jet propeller. The SMA wires were embedded within the soft silica gel formed with cuttlefish mantle shape along the annular direction to mimic the circular muscles of cuttlefish mantle. The water was squeezed out the mantle cavity to form rear jets when the biomimetic mantle was contracted by SMA wires. A mechanical model and a thermal model were established to analyze the jet thrust and the jetting frequency. Theoretical analysis shows that the jet thrust is proportional to the square of the rate of change of SMA strain. Increasing the driving voltage can improve the rate of change of SMA strain, thus can improve both the jet thrust and the jetting frequency. However the jetting frequency is mainly restricted by the cooling of SMA wires. To maximize the jetting frequency, the optimal driving parameters for different driving voltage were calculated. The propulsion performance was tested and the results show that the jet thrust can increase with the driving voltage as predicted and the maximum average jet thrust is 0.14 N when the driving voltage is 25 V. The swimming test was carried out to verify the feasibility of the novel design. It is shown that the biomimetic jet propeller can swim with higher speed as the jet thrust and jetting frequency increase and the maximum speed can reach 8.76 cm·s−1 (0.35 BL·s−1) at a jetting frequency of 0.83 Hz.

0019 The occupational JP8 exposure neuroepidemiology study; evaluation of neuropsychological effects

ObjectivesOne of the most prevalent workplace chemical exposures historically and currently confronting the global military and civilian workforce is jet propellant (JP) fuel. To date, numerous protective and preventive strategies...

Aperture effects in squid jet propulsion

Squid are the largest jet propellers in nature as adults, but as paralarvae they are some of the smallest, faced with the inherent inefficiency of jet propulsion at a low Reynolds number. In this study we describe the behavior and kinematics of locomotion in 1 mm paralarvae of Dosidicus gigas, the smallest squid yet studied. They swim with hop-and-sink behavior and can engage in fast jets by reducing the size of the mantle aperture during the contraction phase of a jetting cycle. We go on to explore the general effects of a variable mantle and funnel aperture in a theoretical model of jet propulsion scaled from the smallest (1 mm mantle length) to the largest (3 m) squid. Aperture reduction during mantle contraction increases propulsive efficiency at all squid sizes, although 1 mm squid still suffer from low efficiency (20%) because of a limited speed of contraction. Efficiency increases to a peak of 40% for 1 cm squid, then slowly declines. Squid larger than 6 cm must either reduce contraction speed or increase aperture size to maintain stress within maximal muscle tolerance. Ecological pressure to maintain maximum velocity may lead them to increase aperture size, which reduces efficiency. This effect might be ameliorated by nonaxial flow during the refill phase of the cycle. Our model's predictions highlight areas for future empirical work, and emphasize the existence of complex behavioral options for maximizing efficiency at both very small and large sizes.

Blood Lead Level and Types of Aviation Fuel in Aircraft Maintenance Crew

This study inquired into any significant difference in blood lead levels (BLLs) among aircraft maintenance crews at the air-bases, each with a different aviation fuel in use, and confirmed an environmental impact of leaded aviation gasoline (AVGAS). This study included a total of 256 male aircraft maintenance personnel, among whom 105 used only AVGAS as their aviation fuel, while 151 used only jet propellant 8 (JP-8), a kerosene variety. BLLs were measured and the data on related factors were obtained. The arithmetic and geometric means of BLLs of the personnel at the airbases that used only AVGAS were 4.20 microg x dl(-1) and 4.01 microg x dl(-1) and that used only JP-8 were 3.79 microg x dl(-1) and 3.57 microg x dl(-1), respectively. The BLLs of the maintenance crew of the main workspace that was located within a 200-m distance from the runway were higher than those of the main workspace that was located 200 m or farther from the runway. The longer the work hours in the runway or the longer the work duration, the higher the BLLs of the maintenance crew. This investigation exposed the fact that a body's BLL could be increased by AVGAS emissions through the examination of aircraft maintenance crew. This result is in agreement with results of previous studies that suggest proximity to an airport may be associated with elevated BLLs for adults and children. Collectively, the results of the current study and previous research suggest that long-duration inhabitation and/or activities in close proximity to an air facility should be limited given that lead poses known health risks.

The effect of the propeller jet on pile groups

The objective of this study is to determine the effect of jet propeller on the damage of berthing structures combined of armoured slope with pile groups. For this purpose, scour measurements were performed for four types berthing structures, which were armoured slope with tandem arrangements of piles for two and three piles and with side by side arrangements of piles for two and three piles. The effect of gap between piles on damage was investigated. The damage level induced by propeller jet between piles was determined. The gaps were 1, 2, 3, and 4 times the pile diameter. Three different values of R pm (690, 820, and 950) were chosen for the tests. The diameter of circular piles is 40 mm. The slope ratio was 1/3 and the diameter of propeller was 10 cm.

Design and Mechanical Property of a Biomimetic Pulsatile Jet Propeller Inspired by Cuttlefish Actuated by SMA Wires

An experimental biomimetic pulsatile jet propeller for robot cuttlefish is presented. Firstly the mechanism of jet swimming of cuttlefish and their mantle muscle structure was analyzed. Secondly the pulsatile jet propeller which is actuated by SMA wires was designed. Then the mechanical properties of the propeller were tested through experiment. The experimental result shows that the propeller can generate thrust force and the maximum thrust force can reach 600 mN. At last, the swimming experiments are carried out and the maximum swimming speed is 8.7 cm/s.

Investigation of Physical and Chemical Delay Periods of Different Fuels in the Ignition Quality Tester

This paper investigates the physical and chemical ignition delay (ID) periods in the constant volume combustion chamber of the Ignition Quality Tester (IQT). IQT was used to determine the derived cetane number (DCN) according to ASTM D6890-10a standards. The fuels tested were ultra low sulfur diesel (ULSD), jet propellant-8 (JP-8), and two synthetic fuels of Sasol IPK and F-T SPK (S-8). A comparison was made between the DCN and cetane number (CN) determined according to ASTM-D613 standards. Tests were conducted under steady state conditions at a constant pressure of 21 bars and various air temperatures ranging from 778 K to 848 K. The rate of heat release (RHR) was calculated from the measured pressure trace, and a detailed analysis of the RHR trace was made particularly for the auto-ignition process. Tests were conducted to determine the physical and chemical delay periods by comparing results obtained from two tests. In the first test, the fuel was injected into air according to ASTM standards. In the second test, the fuel was injected into nitrogen. The point at which the two resultant pressure traces separated was considered to be the end of the physical delay period. The effects of the charge temperature on the total ID as defined in ASTM D6890-10a standards, as well as on the physical and chemical delays, were determined. It was noticed that the physical delay represented a significant part of the total ID over all the air temperatures covered in this investigation. Arrhenius plots were developed to determine the apparent activation energy for each fuel using different IDs. The first was based on the total ID measured according to ASTM standards. The second was the chemical delay determined in this investigation. The activation energy calculated from the total ID showed higher values for lower CN fuels except Sasol IPK. The activation energy calculated from the chemical delay period showed consistency in the increase of the activation energy with the drop in CN including Sasol IPK. The difference between the two findings could be explained by examining the sensitivity of the physical delay period of different fuels to the change in air temperature.

Prototype Design of a Kind of Biomimetic Cuttlefish Underwater Robot Actuated by SMA Wires

Cuttlefish can swim with great maneuverability by undulating their fins and can swim with high speed by jetting.To mimic the muscle structure of the cuttlefish,a kind of flexible fin unit which can bend to both sides and a kind of biomimetic mantle which can flexibly contract and expand,are developed with the structure that SMA(shape memory alloy) wires are embedded into the flexible silicone rubber.Then a kind of biomimetic undulating fin and a kind of biomimetic jet propeller based on the former design are developed to mimic the swimming mechanism of cuttlefish.And the thrust performance of both of the propellers is tested.At last,a prototype of biomimetic cuttlefish robot is developed and the swimming experiments are carried out.

Multiphase Extraction of Light Non-aqueous Phase Liquid (LNAPL) Using Prefabricated Vertical Wells

Work in this paper describes the results of a field and modeling study conducted to investigate the extraction of LNAPL (jet propellant 4, i.e., JP-4, jet fuel) using Prefabricated Vertical Wells (PVWs) at a former air force base. Field testing consisted of 185 operating hours on 25 rows, each consisting of 7 or 8 PVWs. A total of 133 L of free-phase liquid is removed from the subsurface in addition to 467 kg of organics in the vapor phase as a result of volatilization due to the application of vacuum heads exceeding the JP-4 vapor pressure. Monitored field data are used to calibrate a numerical model for investigating the effect of irreducible water content, LNAPL, and gas contents on system performance. Analysis results show that increasing the irreducible water content from 5 % to 20 % decreases the free-LNAPL specific volume from 0.08 m to 0.067 m, which led to reduction in removal efficiency. Under a continuous saturation condition, more wetting fluid (water), traps the nonwetting fluid (LNAPL) in the soil pores, and reduces its mobility, which eventually impedes the LNAPL recovery. Given the model parameters that simulate field conditions, the PVWs show best removal rates in the gas phase. The model results indicated that 292 L of JP-4 can be recovered in 19.5 days (based on 8 h of operation per day) with an effective rate of 1.87 L/h. At the end of 4.25 years of system operation, the maximum benzene concentration is 0.002 ppm. At a gas extraction rate of 10,273 L/min, a maximum concentration of 0.38 ppm in the vapor phase is achieved after 2.5 years of vapor extraction.

Development of a High-Throughput Methodology for Screening Coking Resistance of Modified Thin-Film Catalysts

A high-throughput optical technique has been developed for the rapid screening of coking resistant composition-spread promoted-catalyst libraries during hydrocarbon cracking, in particular for Jet Propellant 8(JP-8) cracking. The libraries are screened by measuring changes in the catalyst's surface color due to the accumulation and burnoff of coke from the surface during JP-8 exposure and catalyst regeneration via oxygen burnoff. This rapid screening method was validated through a comparison of the coking properties of high-surface area powder cracking catalysts, and sputter deposited samples. Experiments on bimetallic (Pt-Gd) catalysts showed systematic trends consistently illustrating the superiority of Pt-Gd alloys to coking due to the presence of gadolinium.

Measurement of Laminar Burning Speeds and Determination of Onset of Auto-Ignition of Jet-A/Air and Jet Propellant-8/Air Mixtures in a Constant Volume Spherical Chamber

The laminar burning speeds of Jet-A/air and three different samples of jet propellant (JP-8)/air mixtures have been measured and the onset of auto-ignition in JP-8/air premixed mixtures has been determined. The experiments were made in a constant volume spherical vessel, which can withstand high pressures up to 400 atm. Burning speed was calculated from dynamic pressure rise due to the combustion process in the vessel. A thermodynamic model based on the pressure rise was used to determine the burning speed. The burning speeds were measured in lean mixtures for pressures of 1–4.5 atm and temperatures of 493–700 K. The onset of auto-ignition of JP-8 fuels was evaluated by observing intense fluctuations of pressure data during the explosion of the unburned gas. It was revealed that Jet-A and JP-8 have very similar burning speeds; however, auto-ignition temperatures of various samples of JP-8 were slightly different from each other. Auto-ignition of these fuels was much more sensitive to temperature rather than pressure.

Single-step catalytic liquid-phase hydroconversion of DCPD into high energy density fuel exo-THDCPD

Hydroconversion of dicyclopentadiene (DCPD) into high energy density jet propellant JP-10 has been successfully achieved with a greener single-step route over supported gold catalyst. The physicochemical properties of the catalysts were studied with XRD, SEM, TEM, N2-adsorption, NH3-TPD. The influence of reaction conditions like temperature, pressure, time etc. were studied in detail. The studies reveal that pressure and temperature play crucial roles in the reaction. Moderate acid sites in the catalysts are chiefly involved in isomerization and gold catalyzes hydrogenation of the intermediates. Analysis of the product stream at different intervals indicates a dissociation–recombination mechanism for the reaction. Reusability of the catalyst was tested by conducting five runs with the same catalyst. Even after the fifth run, the catalyst retains relatively high conversion and selectivity to exo-tetrahydrodicyclopentadiene (exo-THDCPD).

Effect of Biodiesel, Jet Propellant (JP-8) and Ultra Low Sulfur Diesel Fuel on Auto-Ignition, Combustion, Performance and Emissions in a Single Cylinder Diesel Engine

Concern about the depletion of petroleum reserves, rising prices of conventional fuels, security of supply and global warming have driven research toward the development of renewable fuels for use in diesel engines. These fuels have different physical and chemical properties that affect the diesel combustion process. This paper compares between the autoignition, combustion, performance and emissions of soy-bean derived biodiesel, Jet propellant (JP-8) and ultra low sulfur diesel (ULSD) in a high speed single-cylinder research diesel engine equipped with a common rail injection system. Tests were conducted at steady state conditions at different injection pressures ranging from 600 bar to 1200 bar. The ‘rate of heat release’ traces are analyzed to determine the effect of fuel properties on the ignition delay, premixed combustion fraction and mixing and diffusion controlled combustion fractions. Biodiesel produced the largest diffusion controlled combustion fraction at all injection pressures compared to ULSD and JP-8. At 600 bar injection pressure, the diffusion controlled combustion fraction for biodiesel was 53% whereas both JP-8 and ULSD produced 39%. In addition, the effect of fuel properties on engine performance, fuel economy, and engine-out emissions is determined. On an average JP-8 produced 3% higher thermal efficiency than ULSD. Special attention is given to the oxides of nitrogen (NOx) emissions and particulate matter characteristics. On an average biodiesel produced 37% less NOx emissions compared to ULSD and JP-8.

A novel microwave combustion approach for single step synthesis of α-Al 2O 3 nanopowders

A novel method for synthesis of nano-sized α-Al 2O 3 particles in a single step using microwave is being reported for the first time. The sol of aluminum nitrate with urea mixed in the stoichiometric ratios in accordance with jet propellant chemistry, when combusted in a microwave oven gave fine single phase α-Al 2O 3 nanoparticles. The resultant oxide powder was characterized by TGA (Thermo-Gravimetric Analysis), FTIR (Fourier Transform Infra-Red Spectroscopy), XRD (X-ray Diffraction) and TEM (Transmission Electron Microscopy). The XRD analysis of the microwave combusted powder showed complete formation single phase α-Al 2O 3 without contamination of other phases of alumina. In comparison to the well known furnace combustion method for the direct synthesis of α-Al 2O 3, microwave combustion gave finer particles with very small agglomerate size as revealed by TEM analysis.

The Occupational JP8 Exposure Neuroepidemiology Study (OJENES): Repeated workday exposure and central nervous system functioning among US Air Force personnel

One of the most prevalent workplace chemical exposures historically and currently confronting the global military and civilian workforce is jet propellant (JP) fuel (e.g., JP4, JP5, JP8, jet A1), a complex mixture of numerous hydrocarbon compounds and additives. To date, numerous protective and preventive strategies (e.g., federal exposure limits, workplace procedure protocols, protective gear such as goggles, respirator use, gloves, and coveralls) have been put in place to minimize acutely toxic exposure levels. However, questions remain regarding the effect of repeated exposures at lower (than regulated) levels of JP fuel. The Occupational JP8 Exposure Neuroepidemiology Study (OJENES) was designed to examine the relationships between occupational JP8 exposure over multiple, repeated workdays and specific aspects of central nervous system (CNS) functioning among Air Force (AF) personnel. In this report, we present the OJENES methodology, descriptive findings related to participant characteristics, JP8 exposure levels observed over a work week among higher and lower exposure groups, and neuropsychological task performances at the first study assessment. Results indicated minimal differences between participants in the high and lower exposure groups in terms of descriptive characteristics, other than daily JP8 exposure levels (p<0.001). In addition, neuropsychological task performances for most task measures were not found to be significantly different from reported reference ranges. These findings demonstrated that confounding and misclassification of exposure and outcome status are not major concerns for the study. Therefore, future OJENES analyses targeting the more focused research questions regarding associations between JP8 exposure and CNS functioning are likely to provide valid conclusions, as they will be less influenced by these research biases.

Flame Studies of Conventional and Alternative Jet Fuels

Laminar flame speeds and extinction limits of premixed and nonpremixed flames of conventional jet fuels, such as jet propellant 7 and jet propellant 8, and alternative jet fuels, such as synthetic and bioderived, were determined in the counterflow configuration at atmospheric pressure and elevated unburned reactant temperature. The results were compared against those of flames of n-decane and n-dodecane, both being candidate components of jet fuel surrogates. Results indicate that jet propellant 8/air and jet propellant 7/air flames exhibit lower propagation speeds and resistance to extinction compared with flames of alternative fuels. The reduced reactivities of jet propellant 8/air and jet propellant 7/air flames are caused by the alkylcycloparaffins and alkylbenzenes that are present in notable quantities in conventional jet fuels. The combustion characteristics of bioderived jet fuels were found to be indistinguishable from those produced synthetically via the Fischer–Tropsch process. The phenomena of flame propagation and extinction were modeled using n-decane and n-dodecane flames, for which kinetic models are available and for which the molecular weight is representative of that of practical jet fuels. Sensitivity analysis was performed, and results revealed that, compared with flame propagation, flame extinction is, in general, more sensitive to kinetics and diffusion, especially under nonpremixed conditions.

Experimental Investigation of Combustion of Jet Fuels and Surrogates in Nonpremixed Flows

Experimental studies are carried out to characterize nonpremixed combustion of jet fuels and a number of their surrogatesinlaminarnonuniform flows.Thecounterflowconfigurationisemployed.Criticalconditionsofextinction and autoignition are measured for jet propellant 8, Jet-A, and Fisher–Tropsch jet propellant 8. Thirteen surrogates of jetpropellant 8andone surrogate of Fisher–Tropsch jet propellant 8are tested. Itis foundthat criticalconditions of extinction and autoignition of jet propellant 8 and Jet-A are similar, while Fisher–Tropsch jet propellant 8 is morereactivethanjetpropellant8andJet-A.Amongthesurrogatestested,surrogateH[madeupofn-decane(80%) and 1, 3, 5-trimethylbenzene (20%) by liquid volume] and surrogate C [made up of n-dodecane (60%), methylcyclohexane (20%), and o-xylene (20%) by liquid volume] best reproduce extinction and autoignition characteristics of jet propellant 8. Surrogate G [made up ofn-decane (60%) and iso-octane (40%) by liquid volume] best reproduces the combustion characteristics of Fisher–Tropsch jet propellant 8.

Epigenetic Transgenerational Actions of Various Environmental Compounds on Pubertal Onset and Gonadal Function.

The transgenerational actions of several environmental contaminants and compound mixtures were investigated including pesticides (permethrin and N,N-Diethyl-meta-toluamide, DEET), plastics (bisphenol-A and phthalates), dioxin (2,3,7,8-Tetrachlorodibenzo-p-dioxin, TCDD) and a hydrocarbon mixture (jet fuel, Jet Propellant 8, JP8). Vinclozolin exposure was used as a positive control and vehicle treatment was used as a negative control with F0 gestating female rat being treated. Treatments were administered during gonadal sex determination from embryonic day 8 through day 14. The effects were considered transgenerational if disease phenotypes were found in the F3 generation offspring. Transgenerational disease phenotypes were observed in F3 generation within and until 120 days of age and they included alterations in the body and gonad weights, in the onset of puberty and in gonadal function. The pubertal onset of females (vaginal opening) and males (balano-preputial separation) was assessed. Gonadal function was examined by ovarian follicular and cyst counts in females and in males by testicular apoptotic germ cell counts (Terminal deoxynucleotidyl transferase dUTP nick end labeling or TUNEL assay), and by sperm concentrations. The female body weight increased in jet fuel group and the male body weight increased in the plastics, dioxin and jet fuel groups. Both ovary and testis weights were reduced in the plastics, dioxin and jet fuel groups. Sperm concentration was decreased in the plastics group. Females in the plastics, dioxin and jet fuel groups showed an early onset of puberty. There was increased spermatogenic cell apoptosis in testis of males from vinclozolin and jet fuel groups. Decreased ovarian primordial follicle pool size was observed for all the treatment groups and increased ovarian cyst formation was found in vinclozolin, pesticide, dioxin and jet fuel groups. Therefore, like vinclozolin, plastics, dioxin and jet fuel can also induce transgenerational inheritance of disease states (early onset of puberty, increase in body weight, reduction in gonad weight, reduction in ovarian follicle pool size and increase in spermatogenic cell apoptosis) through germ-line mediated epigenetic mechanisms. Thus each treatment is able to alter the sperm epigenome to influence the transgenerational transmission of diseases. Supported by US Department of Defense and National Institutes of Health. (poster)

Identification and characterization of microbial contaminants isolated from stored aviation fuels by DNA sequencing and restriction fragment length analysis of a PCR-amplified region of the 16S rRNA gene

Microorganisms contaminating aircraft fuel tanks containing jet propellant-8 (JP-8) were isolated and identified by 16S rRNA gene sequencing. Thirty-three samples from six geographically separated airport bases were collected. Two bacterial genera were identified by DNA sequencing including the following isolates: Agrobacterium tumefaciens and Staphylococcus epidermidis. Populations of the above species recovered on culture media ranged from 10 to 10 3 CFU/ml with Staphylococcus and Agrobacterium being identified in samples taken from more than one airport base. From the bacterial communities isolated and identified in this study, only Staphylococcus was previously reported to thrive in aviation fuel tanks. Changes in aviation fuel composition and/or the ability of certain microbes to grow under certain environmental conditions may account for the isolation of previously undocumented bacterial species in aviation fuel tanks. Restriction fragment length analysis of the PCR-product proved a more reliable, simpler and quicker method to distinguish S. epidermidis and A. tumefaciens than conventional DNA sequencing.

In vitro time- and dose-effect response of JP-8 and S-8 jet fuel on alveolar type II epithelial cells of rats

This study was designed to characterize and compare the effects of jet propellant-8 (JP-8) fuel and synthetic-8 (S-8) on cell viability and nitric oxide synthesis in cultured alveolar type II epithelial cells of rats. Exposure times varied from 0.25, 0.5, 1, and 6 hours at the following concentrations of jet fuel: 0.0, 0.1, 0.4, and 2.0 microg/mL. Data indicate that JP-8 presents a gradual decline in cell viability and steady elevation in nitric oxide release as exposure concentrations increase. At a 2.0 microg/mL concentration of JP-8, nearly all of the cells are not viable. Moreover, S-8 exposure to rat type II lung cells demonstrated an abrupt fall in percentage cell viability and increases in nitric oxide measurement, particularly after the 2.0 microg/mL was reached at 1 and 6 hours. At 0.0, 0.2, and 0.4 microg/mL concentrations of S-8, percentage viability was sustained at steady concentrations. The results suggest different epithelial toxicity and mechanistic effects of S-8 and JP-8, providing further insight concerning the impairment imposed at specific levels of lung function and pathology induced by the different fuels.