The Experts below are selected from a list of 264 Experts worldwide ranked by ideXlab platform
William F. S. Sellers - One of the best experts on this subject based on the ideXlab platform.
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Asthma pressurised metered dose inhaler performance: Propellant effect studies in delivery systems
Allergy Asthma & Clinical Immunology, 2017Co-Authors: William F. S. SellersAbstract:Background Current pressurised metered dose asthma inhaler (pMDI) Propellants are not inert pharmacologically as were previous chlorofluorocarbons, have smooth muscle relaxant‚ partial pressure effects in the lungs and inhaled hydrofluoroalkane 134a (norflurane) has anaesthetic effects. Volumes of Propellant Gas per actuation have never been measured. Methods In-vitro studies measured Gas volumes produced by pMDIs on air oxygen (O_2) levels in valved holding chambers (VHC) and the falls in O_2% following actuation into lung ventilator delivery devices. Results Volumes of Propellant Gas hydrofluoroalkane (HFA) 134a and 227ea and redundant chlorofluorocarbons (CFC) varied from 7 ml per actuation from a small salbutamol HFA inhaler to 16 ml from the larger. Similar-sized CFC pMDI volumes were 15.6 and 20.4 ml. Each HFA salbutamol inhaler has 220 full volume discharges; total volume of Gas from a small 134a pMDI was 1640 ml, and large 3885 ml. Sensing the presence of liquid Propellant by shaking was felt at the 220th discharge in both large and small inhalers. Because of a partial pressure effect, VHC O_2% in air was reduced to 11% in the smallest 127 ml volume VHC following 10 actuations of a large 134a salbutamol inhaler. The four ventilator delivery devices studied lowered 100% oxygen levels to a range of 93 to 81% after five actuations, depending on the device and type of pMDI used. Conclusion Pressurised inhaler Propellants require further study to assess smooth muscle relaxing properties.
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Asthma pressurised metered dose inhaler performance: Propellant effect studies in delivery systems.
Allergy Asthma & Clinical Immunology, 2017Co-Authors: William F. S. SellersAbstract:Current pressurised metered dose asthma inhaler (pMDI) Propellants are not inert pharmacologically as were previous chlorofluorocarbons, have smooth muscle relaxant‚ partial pressure effects in the lungs and inhaled hydrofluoroalkane 134a (norflurane) has anaesthetic effects. Volumes of Propellant Gas per actuation have never been measured. In-vitro studies measured Gas volumes produced by pMDIs on air oxygen (O2) levels in valved holding chambers (VHC) and the falls in O2% following actuation into lung ventilator delivery devices. Volumes of Propellant Gas hydrofluoroalkane (HFA) 134a and 227ea and redundant chlorofluorocarbons (CFC) varied from 7 ml per actuation from a small salbutamol HFA inhaler to 16 ml from the larger. Similar-sized CFC pMDI volumes were 15.6 and 20.4 ml. Each HFA salbutamol inhaler has 220 full volume discharges; total volume of Gas from a small 134a pMDI was 1640 ml, and large 3885 ml. Sensing the presence of liquid Propellant by shaking was felt at the 220th discharge in both large and small inhalers. Because of a partial pressure effect, VHC O2% in air was reduced to 11% in the smallest 127 ml volume VHC following 10 actuations of a large 134a salbutamol inhaler. The four ventilator delivery devices studied lowered 100% oxygen levels to a range of 93 to 81% after five actuations, depending on the device and type of pMDI used. Pressurised inhaler Propellants require further study to assess smooth muscle relaxing properties.
Moongeun Hong - One of the best experts on this subject based on the ideXlab platform.
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Experimental correction of combustion Gas properties of AN-based composite solid Propellants used for turbo-pump starter
Aerospace Science and Technology, 2012Co-Authors: Moongeun HongAbstract:Abstract Solid Propellant Gas generators play a role as a turbo-pump starter in liquid Propellant propulsion systems by supplying pressurized Gas to power turbines for engine start. Among the required combustion Gas properties provided by solid Propellant Gas generators, the combustion Gas temperature should not exceed a certain temperature which may damage the turbine blades. For such purposes, phase stabilized ammonium nitrate (AN)-based Propellants have been widely used with a low combustion temperature. However, Gas generator Propellants with ammonium nitrate have historically exhibited incomplete combustion resulting in increased flame temperatures differing significantly from equilibrium values. In consideration of design requirements, an engineering model of solid Propellant Gas generator was manufactured using the combustion Gas properties calculated by a chemical equilibrium code and then hot-fire tests were performed. Procedures for the correction of T 0 , k and M w of the combustion Gas from the experimental results are introduced and the following effects on the design of the solid Propellant Gas generator are presented. From the experimental correction of the combustion Gas properties, it is found that the amount of the Propellant could be reduced while providing the same amount of available power to the turbines and consequently, the size of the Gas generator could also be decreased.
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On the effect of filters for the design of solid Propellant Gas generators
Experimental Thermal and Fluid Science, 2008Co-Authors: Moongeun Hong, Soo Yong LeeAbstract:Solid Propellant Gas generator (SPGG) plays a role as a turbo pump starter in liquid Propellant propulsion systems by supplying pressurized Gas to power turbines for engine start. For such a purpose, the Propellant should burn with a low flame temperature and the combustion Gas should not contain corrosive constituents. Stabilized AN-based Propellants have been used as the most appropriate Propellant compositions that meet these requirements. However, because of its low burning rate, the burning area of the Propellant intends to increase to satisfy the required mass flux and consequently the burning area increment brings on the SPGG size augmentation. A flow restriction such as filters, which are usually employed to filter off impurities in the combustion Gas, is applied to decrease the SPGG size by rising up the combustion pressure resulting in increasing the burning rate. Pressure loss coefficient effects on the combustion pressure and on the SPGG/turbines system are investigated with the experimental results. Then the feasibility of the SPGG size reduction by the employment of filters has been studied. The preliminary results of this study show that the considerable reduction of SPGG size would be achievable just by installing a filter with a relatively high pressure loss coefficient.
Soo Yong Lee - One of the best experts on this subject based on the ideXlab platform.
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On the effect of filters for the design of solid Propellant Gas generators
Experimental Thermal and Fluid Science, 2008Co-Authors: Moongeun Hong, Soo Yong LeeAbstract:Solid Propellant Gas generator (SPGG) plays a role as a turbo pump starter in liquid Propellant propulsion systems by supplying pressurized Gas to power turbines for engine start. For such a purpose, the Propellant should burn with a low flame temperature and the combustion Gas should not contain corrosive constituents. Stabilized AN-based Propellants have been used as the most appropriate Propellant compositions that meet these requirements. However, because of its low burning rate, the burning area of the Propellant intends to increase to satisfy the required mass flux and consequently the burning area increment brings on the SPGG size augmentation. A flow restriction such as filters, which are usually employed to filter off impurities in the combustion Gas, is applied to decrease the SPGG size by rising up the combustion pressure resulting in increasing the burning rate. Pressure loss coefficient effects on the combustion pressure and on the SPGG/turbines system are investigated with the experimental results. Then the feasibility of the SPGG size reduction by the employment of filters has been studied. The preliminary results of this study show that the considerable reduction of SPGG size would be achievable just by installing a filter with a relatively high pressure loss coefficient.
John L. Power - One of the best experts on this subject based on the ideXlab platform.
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Preliminary investigation of high power microwave plasmas for electrothermal thruster use
29th Joint Propulsion Conference and Exhibit, 1993Co-Authors: John L. Power, Daniel J. SullivanAbstract:Results are reported from preliminary tests to evaluate the high power microwave electrothermal thruster (MET) concept, which employs a free-floating plasma discharge maintained by applied CW microwave power to heat a Propellant Gas flow. Stable plasmas have been created and maintained in helium (He), nitrogen (N2), and hydrogen (H2) as Propellants in both the TM(sub 011) and TM(sub 012) modes at discharge pressures from 10 Pa to 69 kPa. Reproducible starting conditions of pressure and power have been documented for all the plasmas. Vortical inflow of the Propellant Gas was observed to cause the formation of on-axis 'spike' plasmas. The formation and unformation conditions of these plasmas were studied. Operation in the spike plasma condition enables maximum power absorption with minimum wall heating and offers maximum efficiency in heating the Propellant Gas. In the spike condition, plasmas of the three Propellant Gases were investigated in an open channel configuration to a maximum applied power level of 11.2 kW (in N2). Microwave power coupling efficiencies of over 90 percent were routinely obtained at absorbed power levels up to 2 kW. Magnetic nozzle effects were investigated with a superconducting solenoid Al magnet applying a high magnetic field to the plasmas in and exiting from the discharge tube.
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Microwave electrothermal propulsion for space
IEEE Transactions on Microwave Theory and Techniques, 1992Co-Authors: John L. PowerAbstract:The microwave electrothermal thruster (MET) is attractive for medium- or high-power spacecraft propulsion. A Propellant Gas is heated by passing it through a microwave plasma discharge created in a resonant cavity by tuning either the TM
Yong Cao - One of the best experts on this subject based on the ideXlab platform.
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Effect of vortex inlet mode on low-power cylindrical Hall thruster
Physics of Plasmas, 2017Co-Authors: Yongjie Ding, Boyang Jia, Liqiu Wei, Hezhi Sun, Wuji Peng, Yong CaoAbstract:This paper examines a new Propellant inlet mode for a low-power cylindrical Hall thruster called the vortex inlet mode. This new mode makes Propellant Gas diffuse in the form of a circumferential vortex in the discharge channel of the thruster. Simulation and experimental results show that the neutral Gas density in the discharge channel increases upon the application of the vortex inlet mode, effectively extending the dwell time of the Propellant Gas in the channel. According to the experimental results, the vortex inlet increases the Propellant utilization of the thruster by 3.12%–8.81%, thrust by 1.1%–53.5%, specific impulse by 1.1%–53.5%, thrust-to-power ratio by 10%–63%, and anode efficiency by 1.6%–7.3%, greatly improving the thruster performance.
