Miniature Jet Research Articles

Comprehensive analysis of particle emissions from miniature turbojet engine

Emission of particulate matter from jet engines contribute to deterioration of air quality in the vicinty of the airports and to formation of contrails in higher layers of the atmosphere. This article presents the results of the measurements of particle emissions from a miniature jet engine GTM-120 fueled conventional aviation fuel Jet A-1. Analysis of particle size distribution, number, mass and volume emission indexes has been made, as well as the analysis of the emission intenisty and mass emission rate. Obtained results were related to LTO cycle phases. The results shows, that the particle number concentration was the lowest for low engine loads, with characteristic diameter of 69.8 nm and the particles concentration of 7.7 x 106 particles/cm3. For thrust increase, the characteristic diameter is smaller, and the particles distribution is no longer single-mode. The highest particles concentration for cm3 is for 100% thrust and is equal to 1.55 x 107 particles, with characteristic diameter of 34 nm.

Sustainable aviation fuel – Comprehensive study on highly selective isomerization route towards HEFA based bioadditives

This paper presents the results of a biofuel production process conducted using a cutting-edge, highly selective hydroisomerization catalyst. Rapeseed oil was used as a basic raw material for the synthesis of sustainable aviation fuel. The objective was to verify the catalysts hydroisomerization activity by comparison the effectiveness of obtained biofuel using a miniature jet engine and its compliance with current standards. The developed two-stage process by Łukasiewicz - ICSO involves the conversion of rapeseed oil into a C15–C18 hydrocarbon fraction through hydrodeoxygenation and subsequent hydroisomerization using the Pt/(SAPO-11 + Al2O3) catalyst. The overall average final yield of the aviation fuel fraction (C9–C18) after 500 h of testing was (60 ± 3)% based on the initial rapeseed oil used.In comparison to 100% petrochemical JET A-1 fraction, a BIO50 blend (mixture of biocomponent and JET A-1) is characterized by a more preferable crystallization temperature (−64 °C) and a 50% lower content of aromatic compounds fulfilling all the requirements of ASTM D-7566 standard. Additionally, tests conducted on a miniature jet engine have shown, that the BIO50 mixture has a higher calorific value compared to standard petrochemical fuel, what allows to reduce the overall fuel consumption and slightly lower CO2 and NOx emissions.

Experimental investigation of jet pump performance used for high flow amplification in nuclear applications

The jet pump can be used in a test device of a nuclear reactor for high flow amplification as it reduces inlet flow requirement and thereby size of the process components. In the present work, a miniature jet pump was designed to meet high flow amplification greater than 3. Subsequently, experiments were carried out using a test setup for design validation and performance evaluation of the jet pump for different parameters. It was observed that a minimum pressure of 0.6 bar (g) was required for the secondary fluid inside the jet pump to ensure cavitation free performance at high amplification. Spacing between the nozzle tip and the mixing chamber entry point had significant effect on the performance of the jet pump. Variation in primary flow, temperature and area ratio also affected the performance. It was observed that at high flow amplification, the analytical solution differed significantly from experimental results due to very large velocities encountered in the miniature size jet pump.

Mobile engine test station for preparation and operation of miniature turbine jet engines for flying aerial targets

The work presents description and operation of the mobile engine test station, designed for the miniature turbine jet engines with a maximum trust below 200 N. The engine test bed allows us to monitor the condition of the engine used to drive remotely controlled flying aerial targets or military unmanned aircraft. According to military (Department of Defence) requirements, the designed engine test station is mobile, it can be used in military battlefield conditions and it meets safety precautions and military transport requirements. The reason of the engine investigations was the shortage and lack of information on the engine capability and suitability to work in the field conditions, and first of all on its limitations. The designed engine test station successfully completed tests in laboratory as well as in military field conditions and nowadays it is an integrated part of the Aerial Flying Target System called the ZOCP-JE2 that is designated for the engine’s monitoring and checking before the flight. Keywords: life cycle monitoring, miniature turbine jet engines, diagnostic procedures

Active control of coaxial jet flames under different fuel compositions through manipulation of mixing process with miniature jet actuators

Active control of coaxial jet flames under different fuel compositions through manipulation of mixing process with miniature jet actuators

Measurement of exhaust gas emissions from miniature turbojet engine

This paper presents a methodology developed to measure exhaust gas emissions during operation of a miniature turbojet engine, using a laboratory test rig. The rig has been built for research and development works aimed at modelling and investigating processes and phenomena occurring in jet engines. The miniature jet engines, similarly to full–scale ones used commonly in air transport, are characterized by variable exhaust gas emissions, depending on engine operating parameters. For this reason, an attempt has been made to determine the characteristic features of miniature engine operation modes and to define the variability of operation parameters and exhaust gas emissions as a function of time. According to the authors, the preliminary tests allowed for defining specific profile of engine test, which enables proper measurement regarding exhaust gas emissions using the miniature jet engine. The paper also presents test results for Jet A-1 fuel, according to the used methodology.

Manipulation of Large-Scale Vortical Structures and Mixing in a Coaxial Jet with Miniature Jet Actuators Toward Active Combustion Control

Manipulation of large-scale vortical structures and associated mixing in a methane-air coaxial jet is carried out by using miniature jet actuators installed on the inner surface of the annular nozzle. The periodic radial miniature jet injections are achieved with a rapid-response servo-valve. The spatio-temporal primary jet structures are investigated through phase-locked 2C-PIV (2 Component Particle Image Velocimetry) and stereoscopic-PIV. It is found that intense ring-like vortices are produced perfectly in phase with the periodic miniature jet injections regardless of the valve-driven frequency fv examined. When the Strouhal number Stv, which is defined with fv, is larger than unity, the ring-like vortices are densely formed and thus methane/air mixing is prompted with low periodic fluctuation. The diameter of the vortices becomes small as Stv is increased, so that the transport range of the inner methane and outer air fluids can be controlled by changing Stv. In addition, the evolution of counter-rotating vortex pair is also observed in the cross-sectional plane. These streamwise vortices are directly formed as a result of the radial miniature jet injection, which leads to entrainment of the ambient fluid near the primary jet shear layer, and they also contribute to the mixing enhancement. Moreover, it is demonstrated that coaxial jet flame characteristics such as carbon monoxide (CO) emission and flame holding can be drastically improved under different equivalence ratios by the present jet control scheme.

The laboratory test rig with miniature jet engine to research aviation fuels combustion process

Abstract This article presents laboratory test rig with a miniature turbojet engine (MiniJETRig – Miniature Jet Engine Test Rig), that was built in the Air Force Institute of Technology. The test rig has been developed for research and development works aimed at modelling and investigating processes and phenomena occurring in full scale jet engines. In the article construction of a test rig is described, with a brief discussion on the functionality of each of its main components. Additionally examples of measurement results obtained during the realization of the initial tests have been included, presenting the capabilities of the test rig.

F222 混合過程の操作による異なる組成を持つ模擬バイオガスの燃焼能動制御(OS-03:革新的技術のための燃焼研究(4))

The simulant biogas-air coaxial jet flow and combustion are actively controlled through periodic excitation of the initial jet shear layer with arrayed miniature jet actuators. In the present study, CH_4 fuel is diluted by N_2 or CO_2 with various dilution rates to mimic biogas. Firstly, it is found that the large-scale vortical structures and the associated mixing of biogas-air are flexibly controlled by changing the injection frequency of miniature jet. In addition, it is demonstrated that CO emissions from the biogas flames operated with different fuel dilution rates can be significantly improved by manipulating the mixing upstream of the flame base.

Accurate Xe isotope measurement using JPL ion trap.

We report an approach for the reproducible and accurate compositional analysis of different mixtures of Xe isotopes using miniature Jet Propulsion Laboratory Quadrupole Ion Trap (JPL-QIT). A major study objective was to validate the recent instrumental improvements to the long-term operational stability under different pressures, temperatures, and trapping conditions. We propose that the present device can be used in certification of trace amounts of isotopes in mixtures dominated by one or more isotopes. Measured isotopic compositions are verified against commercially available standards with accuracy better than 0.07%. To aid the analysis of experimental data, we developed a scalable replica fitting method and use peak areas as descriptors of relative isotopic abundances. This low-power and low-mass device is ideally suited for planetary explorations aimed to enhance quantitative analysis for major isotopes present in small amounts of atmospheric samples.

Local two-phase heat transfer from arrays of confined and submerged impinging jets

Local heat transfer distributions at high spatial resolution are obtained under two-phase transport conditions in confined and submerged impingement from arrays of miniature jets. The dielectric liquid HFE-7100 is investigated to enable direct cooling of electronic components. Three round orifice geometries with the same total orifice open area are investigated, including a single orifice of 3.75mm diameter, a 3×3 array of 1.25mm diameter orifices, and a 5×5 array of 0.75mm diameter orifices. A thin-foil heat source backed by a magnesium-fluoride window is fabricated to allow detailed mapping of the heated surface temperature via infrared (IR) thermography. The rigorous experimental calibration procedures employed, and correction for heat spreading within the thermally conductive IR-transparent window, yield low-uncertainty local heat transfer coefficient distributions. Each of the three orifice geometries is characterized at volumetric flow rates of 450ml/min, 900ml/min, and 1800ml/min, resulting in a Reynolds number range of 1920–39400. Pressure drop across the confined jets is measured for all experimental cases. The test facility and measurement techniques employed are validated against heat transfer and pressure drop correlations in the literature for single-phase jet impingement from a single round orifice. Spatially resolved temperature contour maps, along with local heat transfer coefficient and boiling curves, are presented as a function of applied heat flux. Boiling is shown to coexist with single-phase convection under the impinging liquid jets. Two-phase enhancement is exhibited at large radial distances from the single jet axis, and in regions between neighboring jets within the arrays. The arrays of jets result in higher area-averaged heat transfer than a single jet at a fixed flow rate; however, the arrays display larger relative nonuniformity in local two-phase heat transfer coefficient and surface temperature. While the 5×5 array resulted in a higher (and the 3×3 a lower) pressure drop than the single jet, all orifices displayed pressure drop that is independent of the applied heat flux and vapor generation.

Active Control of Methane-Air Coaxial Jet Mixing and Combustion with Arrayed Miniature Jet Actuators

Large-scale vortical structures and associated mixing in a methane-air coaxial jet are actively controlled by manipulating the initial jet shear layer with miniature jet actuators installed on the inner surface of the annular nozzle. The periodic radial miniature jet injections are realized by using a rapid-response pneumatic servovalve, and sinusoidal/pulsed flowing are employed in the present study. The spatio-temporal primary jet structures are investigated through phase-locked 2C-PIV (2 Component Particle Image Velocimetry) and Stereoscopic-PIV. In the pulsed configuration, it is found that intense vortex rings are produced in phase with the periodic control input regardless of the valve-driven frequency fv examined. When the Strouhal number Stv, which is defined with fv, is larger than unity, the vortex rings are densely-shed and thus methane/air mixing is prompted with low periodic fluctuation. The diameter of the vortices becomes small as Stv is increased, so that the transport range of the inner methane and outer air fluids can be controlled by changing Stv. In addition, the evolution of counter-rotating streamwise vortex pair is also confirmed. These streamwise vortices are formed as a result of the radial injection of the miniature jet, which leads to entrainment of the ambient fluid near the primary jet shear layer. They contribute the mixing enhancement in the downstream, where the vortex rings are broken down. Moreover, it is demonstrated that the coaxial jet flame characteristics such as flame holding are drastically improved by the present jet control scheme.

317 微小噴流アクチュエータによるメタン・空気同軸噴流の大規模渦構造および混合の能動制御(OS5-4 燃焼技術の基礎と応用研究(4),OS5 燃焼技術の基礎と応用研究)

317 微小噴流アクチュエータによるメタン・空気同軸噴流の大規模渦構造および混合の能動制御(OS5-4 燃焼技術の基礎と応用研究(4),OS5 燃焼技術の基礎と応用研究)

A liquid-based system for CPU cooling implementing a jet array impingement waterblock and a tube array remote heat exchanger

Abstract A liquid CPU cooler has been designed and tested with the aim to achieve a cooling capacity of 200 W for a surface area of 8.24 cm2, commensurate with the integrated heat spreader dimensions of an Intel® Pentium® 4 Processor. The primary aim of the design was to develop thermal hardware components that can be manufactured simply and cost effectively. To this end, a miniature jet array waterblock and a tube bundle remote heat exchanger were employed since the bulk of their housings could be manufactured using low cost injection molding techniques which could significantly reduce the total system cost compared with conventional units. The system was capable of dissipating the required heat load and exhibited an overall thermal resistance of 0.18 K/W requiring approximately 1.5 W of hydraulic power. At maximum power the chip-to-air temperature difference was 45 °C which is adequately close to typical design thresholds. The influences of power loading and liquid volumetric flow rate are also discussed.

S053031 マイクロ噴流群による単軸円形噴流の大規模渦構造および混合の能動制御

Large-scale vortical structures and associated flow development in an axisymmetric jet are actively controlled by manipulating the initial shear layer with arrayed miniature jet actuators. The periodic radial miniature jet injections are realized by using a rapid-response pneumatic servovalve, and sinusoidal/pulsed flowing are employed in the present study. The spatio-temporal primary jet structures are investigated through phase-locked particle image verocimetry (PIV). In the pulsed configuration, it is found that intense vortex rings are produced in phase with the periodic control input regardless of the valve-driven frequency f_v examined. When the Strouhal number Stv, which is defined with f_v, is larger than unity, the vortex rings are shed continuously and thus the jet flow development is prompted with low periodic velocity fluctuation. The diameter of the vortices becomes small as Stv is increased, so that the transport range of the jet and ambient fluids can be controlled by changing Stv. In addition, the evolution of counter-rotating streamwise vortices is also confirmed. These streamwise vortices are formed as a result of tilting of the primary jet azimuthal vorticity by the miniature jet impinging on the primary jet shear layer. It is conjectured that they contribute the mixing enhancement in the azimuthal direction.

Diode Laser-Driven Microthrusters: A New Departure for Micropropulsion

We developed an entirely new type of orientation thruster for micro- and nanosatellites. The laser plasma thruster is based on the recent commercial availability of diode lasers with sufficient brightness and 100% duty cycle to produce a repetitively pulsed or continuous vapor or plasma jet on a surface in vacuum. A low-voltage semiconductor switch can drive the laser. A lens focuses the laser diode output on the ablation target, producing a miniature jet that provides the thrust. Single-impulse dynamic range is nearly five orders of magnitude, and the minimum impulse bit is 1 nN/s in a 100-„s pulse. Even with diffraction-limited focusing optics, at least 0.5-W optical power is needed to produce thrust from selected ablator materials. Thrust-to-power ratio Cm is 50 to 100„N/W and specific impulse Isp is 200‐500 s with a 1-W laser, depending partially on the illumination mode. Transmission and reflection (R) illumination modes are discussed. R mode gives about 50% better Isp and two times better Cm. Improved results are anticipated from higher laser power in the reflection mode. The prototype engine we are developing is intended to provide lifetime on-orbit steering for a 5-kg satellite, as well as reentering it from low Earth orbit.

Treatment of Respiratory Insufficiency in Infants Using Nasal CPAP and a Gas Jet

A light-weight system for continuous positive airway pressure (CPAP) based on a nasal vestibular cannula and a miniature gas jet has been tried out in 29 newborns with severe idiopathic respiratory distress syndrome (IRDS) and nine infants suffering from respiratory insufficiency caused by lower respiratory tract infections. In infants with IRDS, a permanent effect was achieved in 20% when the birth weight was below 1501 g, and in 74% when the birth weight was higher. The infants with lower respiratory tract infections all recovered without further ventilatory support. Significant complications occurred in only two infants, both of whom developed pneumothorax. The system forms a simple and safe alternative to existing nasal CPAP systems suitable for use in newborns as well as older infants with lung diseases resulting in alveolar collapse.