Coating modification is an important way to enhance the reactivity of aluminum powder.In this paper,ammonium perchlorate and aluminum powder were assembled into energetic microunits by liquid deposition method.Spheric...Coating modification is an important way to enhance the reactivity of aluminum powder.In this paper,ammonium perchlorate and aluminum powder were assembled into energetic microunits by liquid deposition method.Spherical particles with AP as shell and ultrafine aluminum powder as the core(Al@AP)were gained.The micromorphology results show that the coated particles are about 5μm,and the coating layer is evenly distributed on the outer surface of aluminum powder,indicating a complete coating.The energetic microunits were implanted into the nitrate ester plasticizing adhesive system(NEPE)as solid phase fillers.The effect of filler on the rheological properties,safety,mechanical properties,thermal reaction and energy properties of the system was analyzed by comparing with the raw aluminum filler.The test results show that the rheological properties,mechanical properties and pressure index of NEPE containing system Al@AP meets the requirements of solid propellant charging.Compared with Al based propellant,the mechanical sensitivity and thermal sensitivity are decreased,the safety is better,and the explosion heat of the propellant is increased by 7.8%.The engine test shows that the specific impulse is increased by 1.2 s.Al@AP can improve the energy output and safety of NEPE propellant,and has potential application prospects in high-energy propellants.展开更多
Inhibiting the agglomeration of molten aluminum particles packed in the binder network is a promising scheme to achieve efficient combustion of solid propellants.In this investigation,the hydroxyl-terminated structure...Inhibiting the agglomeration of molten aluminum particles packed in the binder network is a promising scheme to achieve efficient combustion of solid propellants.In this investigation,the hydroxyl-terminated structured fluorinated alcohol compound(PFD)was introduced to modify the traditional polyethylene glycol/polytetrahydrofuran block copolymerization(HTPE)binder;that is,a unique fluorinated polyether(FTPE)binder was synthesized by embedding fluorinated organic segments into the HTPE binder via crosslinking curing.The FTPE was applied in aluminum-based propellants for the first time.Due to the complete release of fluorinated organic active segments in the range of 300℃to 400℃,the burning rate of FTPEbased propellant increased from 4.07(0%PFD)to 6.36 mm/s(5%PFD),increased by 56.27%under 1 MPa.The reaction heat of FTPE propellants increased from 5.95(0%PFD)to 7.18 MJ/kg(5%PFD)under 3.0 MPa,indicating that HTPE binder modified with PFD would be conducive to inhibiting the D90 of condensed combustion products(CCPs)dropped by 81.84%from 75.46(0%PFD)to 13.71μm(5%PFD)under 3.0 MPa,in consistent with the significant reduction of aluminum agglomerates observed on the quenched burning surface of the propellants.Those results demonstrated that a novel FTPE binder with PFD can release fluorinated organic active segments,which motivate preignition reaction with the alumina shell in the early stage of aluminum combustion,and then enhance the melting diffusion effect of aluminum to inhibit the agglomeration.展开更多
A novel constant-pressure and constant-quenching distance Condensed Combustion Products(CCPs)collection system was developed,coupled with a timing control system,to collect the CCPs formed in the course of burning of ...A novel constant-pressure and constant-quenching distance Condensed Combustion Products(CCPs)collection system was developed,coupled with a timing control system,to collect the CCPs formed in the course of burning of aluminum-based composite propellants.The effects of adiabatic graphite plating,collection zone,quenching distance,time series of collection,and propellant burning rate on the microscopic morphology,particle size distribution and unburned aluminum content of CCPs were investigated.It was verified that the graphite plating can provide a high-fidelity high-temperature environment for propellant combustion.The combustion efficiency is improved by 2.44% compared to the bare propellant case.The time series of collection has a significant effect on the combustion efficiency of aluminum,and the combustion efficiency of aluminum in the thermal state(1.2-2.4 s)is 2.75% higher than that in the cold state(0-1.2 s).Similarly,the characteristics of the CCPs in different collection zones are different.At the quenching distance of 5 mm,the combustion efficiency of aluminum in the core zone(85.39%)is much lower than that in the outer zone(92.07%),while the particle size of the CCPs in the core zone(172μm)is larger than that in the outer zone(41μm).This indicates that the core zone is more likely to produce large-sized and incompletely burned agglomerates during the propellant combustion process.Different burning rates also lead to a significant difference in particle size distribution and combustion efficiency.High burning rates result in higher combustion efficiency.A detailed sequence of the elaborative collection process of CCPs is proposed,mainly including the setting of ignition delay time,burning rate,working pressure,plating length and time series of collection.The findings of this study are expected to provide a reliable tool for the evaluation of the combustion efficiency of solid propellants.展开更多
The effects of modifiers on the anti-wetting and anti-icing property of the prepared rough aluminum surface were investigated.The rough aluminum substrates were obtained through electrochemical oxidization with 15 wt%...The effects of modifiers on the anti-wetting and anti-icing property of the prepared rough aluminum surface were investigated.The rough aluminum substrates were obtained through electrochemical oxidization with 15 wt% sulfuric acid solution as the electrolyte at the constant current of 4 mA for 3 h.And then they were modified with octadecanoic acid (C18),polyethylene (PE),polystyrene (PS),polyethylene glycol (PEG) and hexamethylenetetramine (HMTA),respectively,whose surface free energies were 27.6,31.0,33.0,61.6 and 70.0 mN/m,respectively.The contact angles (CA) were 154.6°,128.4°,127.6°,5.0° and 0.0°,respectively,and the ice adhesion pressures were 15.9,36.3,55.9,155.3 and 216.1 kPa,respectively.The ice adhesion strengths decrease along with the increasing anti-wetting property of aluminum surfaces and the decreasing of the surface energy of modifiers.These provide some new insights when designing the aluminum surface with anti-icing properties in some special applications.展开更多
During ice-breaking navigation, a massive amount of crushed ice blocks with different sizes is accumulated under the hull of an ice-going ship. This ice slides into the flow field in the forward side of the podded pro...During ice-breaking navigation, a massive amount of crushed ice blocks with different sizes is accumulated under the hull of an ice-going ship. This ice slides into the flow field in the forward side of the podded propulsor, affecting the surrounding flow field and aggravating the non-uniformity of the propeller wake. A pulsating load is formed on the propeller, which affects the hydrodynamic performance of the podded propulsor. To study the changes in the propeller hydrodynamic performance during the ice podded propulsor interaction, the overlapping grid technique is used to simulate the unsteady hydrodynamic performance of the podded propulsor at different propeller rotation angles and different ice block sizes. Hence, the hydrodynamic blade behavior during propeller rotation under the interaction between the ice and podded propulsor is discussed. The unsteady propeller loads and surrounding flow fields obtained for ice blocks with different sizes interacting with the podded propulsor are analyzed in detail. The variation in the hydrodynamic performance during the circular motion of a propeller and the influence of ice size variation on the propeller thrust and torque are determined. The calculation results have certain reference significance for experiment-based research, theoretical calculations and numerical simulation concerning ice podded propulsor interaction.展开更多
Cargo ship sailing within the ice channel that an assisting icebreaker tracks in the compact ice cover is the usual navigation practice for difficult ice conditions in freezing seas and Arcticwater areas.When the iceb...Cargo ship sailing within the ice channel that an assisting icebreaker tracks in the compact ice cover is the usual navigation practice for difficult ice conditions in freezing seas and Arcticwater areas.When the icebreaker or an ahead vessel stops before the insuperable ice obstacle or because of engine trouble,the danger of an emergency appears,namely of collision with the icebreaker or the ahead ship,if the interval between them is not sufficient for effective braking and stopping.The paper presents the equation that describes the ship braking process within an ice channel and includes the thrust of the propeller that works under the reverse regime.The specific of this regime is the following:the ship continues the motion‘forwards’and the propeller rotates‘backwards’.An analytical method for description of the ship propeller work on the reverse regime is absent because of the detached flow on its blades.The paper describes the developed empirical method of this regime parameterization on the basis of serial models of propeller testing.The outcomes of this investigation are applied to a ship braking process simulation and the evaluation of the safe interval between the ship and the icebreaker.展开更多
基金supported by Natural Science Foundation (Grant No.21975024)Natural Science Foundation of Inner Mongolia Autonomous Region (Grant No.2021BS05014)。
文摘Coating modification is an important way to enhance the reactivity of aluminum powder.In this paper,ammonium perchlorate and aluminum powder were assembled into energetic microunits by liquid deposition method.Spherical particles with AP as shell and ultrafine aluminum powder as the core(Al@AP)were gained.The micromorphology results show that the coated particles are about 5μm,and the coating layer is evenly distributed on the outer surface of aluminum powder,indicating a complete coating.The energetic microunits were implanted into the nitrate ester plasticizing adhesive system(NEPE)as solid phase fillers.The effect of filler on the rheological properties,safety,mechanical properties,thermal reaction and energy properties of the system was analyzed by comparing with the raw aluminum filler.The test results show that the rheological properties,mechanical properties and pressure index of NEPE containing system Al@AP meets the requirements of solid propellant charging.Compared with Al based propellant,the mechanical sensitivity and thermal sensitivity are decreased,the safety is better,and the explosion heat of the propellant is increased by 7.8%.The engine test shows that the specific impulse is increased by 1.2 s.Al@AP can improve the energy output and safety of NEPE propellant,and has potential application prospects in high-energy propellants.
基金Fundamental Research Funds for the Central Universities,Grant/Award Number:3052017010。
文摘Inhibiting the agglomeration of molten aluminum particles packed in the binder network is a promising scheme to achieve efficient combustion of solid propellants.In this investigation,the hydroxyl-terminated structured fluorinated alcohol compound(PFD)was introduced to modify the traditional polyethylene glycol/polytetrahydrofuran block copolymerization(HTPE)binder;that is,a unique fluorinated polyether(FTPE)binder was synthesized by embedding fluorinated organic segments into the HTPE binder via crosslinking curing.The FTPE was applied in aluminum-based propellants for the first time.Due to the complete release of fluorinated organic active segments in the range of 300℃to 400℃,the burning rate of FTPEbased propellant increased from 4.07(0%PFD)to 6.36 mm/s(5%PFD),increased by 56.27%under 1 MPa.The reaction heat of FTPE propellants increased from 5.95(0%PFD)to 7.18 MJ/kg(5%PFD)under 3.0 MPa,indicating that HTPE binder modified with PFD would be conducive to inhibiting the D90 of condensed combustion products(CCPs)dropped by 81.84%from 75.46(0%PFD)to 13.71μm(5%PFD)under 3.0 MPa,in consistent with the significant reduction of aluminum agglomerates observed on the quenched burning surface of the propellants.Those results demonstrated that a novel FTPE binder with PFD can release fluorinated organic active segments,which motivate preignition reaction with the alumina shell in the early stage of aluminum combustion,and then enhance the melting diffusion effect of aluminum to inhibit the agglomeration.
基金supported by the National Natural Science Foundation of China(Nos.22375164,21975066 and U2241250)the Key Research and Development Program of Shaanxi,China(No.2023KJXX-005)。
文摘A novel constant-pressure and constant-quenching distance Condensed Combustion Products(CCPs)collection system was developed,coupled with a timing control system,to collect the CCPs formed in the course of burning of aluminum-based composite propellants.The effects of adiabatic graphite plating,collection zone,quenching distance,time series of collection,and propellant burning rate on the microscopic morphology,particle size distribution and unburned aluminum content of CCPs were investigated.It was verified that the graphite plating can provide a high-fidelity high-temperature environment for propellant combustion.The combustion efficiency is improved by 2.44% compared to the bare propellant case.The time series of collection has a significant effect on the combustion efficiency of aluminum,and the combustion efficiency of aluminum in the thermal state(1.2-2.4 s)is 2.75% higher than that in the cold state(0-1.2 s).Similarly,the characteristics of the CCPs in different collection zones are different.At the quenching distance of 5 mm,the combustion efficiency of aluminum in the core zone(85.39%)is much lower than that in the outer zone(92.07%),while the particle size of the CCPs in the core zone(172μm)is larger than that in the outer zone(41μm).This indicates that the core zone is more likely to produce large-sized and incompletely burned agglomerates during the propellant combustion process.Different burning rates also lead to a significant difference in particle size distribution and combustion efficiency.High burning rates result in higher combustion efficiency.A detailed sequence of the elaborative collection process of CCPs is proposed,mainly including the setting of ignition delay time,burning rate,working pressure,plating length and time series of collection.The findings of this study are expected to provide a reliable tool for the evaluation of the combustion efficiency of solid propellants.
基金Funded by National Natural Science Foundation of China(No.51801058)the Special Program for Guiding Local Science and Technology Development by the Central Government of Hubei Province(No.2019ZYYD006)Hubei Provincial Natural Science Foundation of China(No.2018CFB759)。
文摘The effects of modifiers on the anti-wetting and anti-icing property of the prepared rough aluminum surface were investigated.The rough aluminum substrates were obtained through electrochemical oxidization with 15 wt% sulfuric acid solution as the electrolyte at the constant current of 4 mA for 3 h.And then they were modified with octadecanoic acid (C18),polyethylene (PE),polystyrene (PS),polyethylene glycol (PEG) and hexamethylenetetramine (HMTA),respectively,whose surface free energies were 27.6,31.0,33.0,61.6 and 70.0 mN/m,respectively.The contact angles (CA) were 154.6°,128.4°,127.6°,5.0° and 0.0°,respectively,and the ice adhesion pressures were 15.9,36.3,55.9,155.3 and 216.1 kPa,respectively.The ice adhesion strengths decrease along with the increasing anti-wetting property of aluminum surfaces and the decreasing of the surface energy of modifiers.These provide some new insights when designing the aluminum surface with anti-icing properties in some special applications.
基金financially supported by the National Natural Science Foundation of China(Grant Nos.51679052,51639004 and51809055)the Defense Industrial Technology Development Program(Grant No.JCKY2016604B001)the Natural Science Foundation of Heilongjiang Province of China(Grant No.E2018026)
文摘During ice-breaking navigation, a massive amount of crushed ice blocks with different sizes is accumulated under the hull of an ice-going ship. This ice slides into the flow field in the forward side of the podded propulsor, affecting the surrounding flow field and aggravating the non-uniformity of the propeller wake. A pulsating load is formed on the propeller, which affects the hydrodynamic performance of the podded propulsor. To study the changes in the propeller hydrodynamic performance during the ice podded propulsor interaction, the overlapping grid technique is used to simulate the unsteady hydrodynamic performance of the podded propulsor at different propeller rotation angles and different ice block sizes. Hence, the hydrodynamic blade behavior during propeller rotation under the interaction between the ice and podded propulsor is discussed. The unsteady propeller loads and surrounding flow fields obtained for ice blocks with different sizes interacting with the podded propulsor are analyzed in detail. The variation in the hydrodynamic performance during the circular motion of a propeller and the influence of ice size variation on the propeller thrust and torque are determined. The calculation results have certain reference significance for experiment-based research, theoretical calculations and numerical simulation concerning ice podded propulsor interaction.
基金Study was implemented within project SIMREC—‘Simulators for Improving Cross-Border Oil Spill Response in Extreme Conditions’(Grant Contact No.1804147-KS1703).
文摘Cargo ship sailing within the ice channel that an assisting icebreaker tracks in the compact ice cover is the usual navigation practice for difficult ice conditions in freezing seas and Arcticwater areas.When the icebreaker or an ahead vessel stops before the insuperable ice obstacle or because of engine trouble,the danger of an emergency appears,namely of collision with the icebreaker or the ahead ship,if the interval between them is not sufficient for effective braking and stopping.The paper presents the equation that describes the ship braking process within an ice channel and includes the thrust of the propeller that works under the reverse regime.The specific of this regime is the following:the ship continues the motion‘forwards’and the propeller rotates‘backwards’.An analytical method for description of the ship propeller work on the reverse regime is absent because of the detached flow on its blades.The paper describes the developed empirical method of this regime parameterization on the basis of serial models of propeller testing.The outcomes of this investigation are applied to a ship braking process simulation and the evaluation of the safe interval between the ship and the icebreaker.
