Low-shear-stress phase change type gel propellant as well as preparation method and application thereof

Abstract

The invention discloses a low-shear-stress phase change type gel propellant and a preparation method and application thereof.The low-shear-stress phase change type gel propellant is prepared from, by mass, 60%-70% of oxidizing agents, 2%-27.5% of metal fuel, 0%-15% of auxiliary fuel, 10%-20% of water, 2%-5% of gels and 0.5%-3% of functional auxiliaries. The gel propellant provided by the invention is converted from a gel state to a liquid state under the action of relatively low shear stress, so that the storage and the conveying of the propellant are facilitated, and atomized injection can be realized. The preparation method of the gel propellant is simple in process, and the prepared gel propellant is stable in performance, has good energy performance and is expected to be applied to the fields of solid-liquid combination engines, gel engines and the like.

Description

Technical Field

[0001] The present invention relates to the technical field of special propellants, and in particular, to a low shear stress phase-change gel propellant, a preparation method thereof, and an application thereof. Background Art

[0002] As a new type of propellant, the unique rheological properties of gel propellants exhibit great application potential in the aerospace field. Gel propellants belong to shear-thinning non-Newtonian fluids. At low shear rates, the three-dimensional network structure formed by internal cross-linking can effectively maintain the shape of the propellant, prevent component stratification and sedimentation, and maintain the storage stability of the gel propellant; at high shear rates, the internal structure of the gel propellant is destroyed, the intermolecular forces are weakened, and it exhibits good fluidity, which is beneficial for pipeline transportation and atomization. Gel propellants not only have the advantages of solid propellants such as being not easy to leak, easy to store, insensitive to impact and collision, and good in use and maintenance, but also have the characteristics of high specific impulse, adjustable thrust, and multiple startups of liquid propellants, and are high-quality new energy for the power part of rocket engines.

[0003] Ammonium dinitramide (ADN) has the advantages of being non-toxic, high-energy, and good chemical stability, and has significant advantages in the field of rocket propellants. The strong hygroscopicity of ADN easily leads to caking and performance degradation, which limits its application. ADN gel propellants combine the advantages of high energy density and chlorine-free low toxicity of ADN, and at the same time use the gel matrix to improve the hygroscopicity and storage stability of ADN. ADN is a white crystalline powder, and its gelation preparation process is relatively complex and costly. At present, there is little research on ADN gels, and the technology for preparing ADN / water-based gel propellants (excluding metal fuels) using silica powder is not yet mature. The intermolecular forces of the gels prepared by relying on the stacking effect of silica are weak, the gel structure is unstable, and phenomena such as sedimentation and liquid leakage are likely to occur. After adding water to the gel system, the energy of the gel propellant is reduced. Summary of the Invention

[0004] The purpose of the present invention is to overcome the above deficiencies of the prior art, and provide a low shear stress phase-change gel propellant, a preparation method thereof, and an application thereof.

[0005] The present invention solves its technical problems by adopting the following technical solutions.

[0006] The present invention provides a low shear stress phase-change gel propellant, which includes the following components by mass percentage: oxidant: 60%-70%, metal fuel: 2%-27.5%, auxiliary fuel: 0%-15%, water: 10%-20%, gelling agent: 2%-5%, and functional auxiliary agent: 0.5%-3%.

[0007] The present invention provides a method for preparing the above-mentioned low shear stress phase-change gel propellant, comprising the following steps:

[0008] S1. Dissolve an oxidizer in water to obtain an oxidizer solution;

[0009] S2. Add a gelling agent and stir to mix until the gelling agent is completely dissolved or evenly dispersed;

[0010] S3. Continuously add a metal fuel, an auxiliary fuel, and a functional additive, mix until evenly dispersed, then heat and stir to form a homogeneous sol, and let it stand and cool naturally to room temperature to form a gel propellant.

[0011] The present invention provides an application of the above-mentioned low shear stress phase-change gel propellant in a solid-liquid hybrid engine and a gel engine.

[0012] The present invention has the following beneficial effects:

[0013] The present invention provides a low shear stress phase-change gel propellant, its preparation method and application. Through the stacking effect of fine particle size metal fuel, the cross-linking effect of the gelling agent and the intermolecular force, a stable three-dimensional network structure is synergistically constructed to restrict the flow of components and form a stable ADN gel propellant. Under static conditions or at a low shear rate, the internal structure of the propellant is stable, and the propellant can maintain the gel state, which is beneficial for storage; under a large shear force, the viscosity of the propellant decreases, which is beneficial for pipeline transportation and atomization, and atomized injection can be realized. The above-mentioned gel propellant has stable performance and high energy density, and is expected to be used in fields such as solid-liquid hybrid engines and gel engines. Description of the Drawings

[0014] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings required to be used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of the present invention, and therefore should not be regarded as limiting the scope. For those of ordinary skill in the art, other related drawings can be obtained based on these drawings without creative efforts.

[0015] Figure 1 It is a sample diagram of the gel propellant prepared in Example 7 of the present invention;

[0016] Figure 2 It is a sample diagram of the gel propellant prepared in Comparative Example 2 of the present invention. Detailed Embodiments

[0017] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be described clearly and completely below. For those not specified in the embodiments, they are carried out according to conventional conditions or the conditions recommended by the manufacturer. For reagents or instruments not specified by the manufacturer, they are all conventional products that can be obtained through commercial purchase.

[0018] The objective of the present invention is to provide a low-shear-stress phase-changeable gel propellant, its preparation method, and application. This gel propellant is a gel propellant that can undergo a phase change under a relatively low shear stress. It has good stability, a simple preparation process, a standard theoretical specific impulse exceeding 250 s, and can be transformed from a gel state to a liquid state under the action of a relatively low shear stress. It is expected to be used in fields such as solid-liquid hybrid engines and gel engines.

[0019] The following specifically describes a low-shear-stress phase-changeable gel propellant, its preparation method, and application provided by the embodiments of the present invention.

[0020] In the first aspect, the embodiments of the present invention provide a low-shear-stress phase-changeable gel propellant, which, by mass percentage, includes the following components: oxidizer: 60%-70%, metal fuel: 2%-27.5%, auxiliary fuel: 0%-15%, water: 10%-20%, gelling agent: 2%-5%, and functional additive: 0.5%-3%.

[0021] The present invention provides a low-shear-stress phase-changeable gel propellant. A low-shear-stress phase-changeable gel propellant refers to a gel propellant that can undergo a phase change under a relatively low shear stress. It mainly constructs a stable three-dimensional network structure through the stacking effect of fine-particle-size metal fuel, the cross-linking effect of the gelling agent, and intermolecular forces to restrict the flow of components and form a stable ADN gel propellant. By endowing the material with specific rheological properties through the gelation process, the internal structure of the propellant is stable when standing or at a relatively low shear rate, and the propellant can maintain a gel state, which is conducive to storage; under a relatively large shear action, the viscosity of the propellant decreases, which is conducive to pipeline transportation and atomization, and atomization injection can be achieved. It is expected to be used in fields such as solid-liquid hybrid engines and gel engines.

[0022] In some optional embodiments, the oxidizer includes ammonium dinitramide.

[0023] In some optional embodiments, the metal fuel includes Al powder, Mg powder, Mg-Al alloy powder, Li-Al alloy powder, spherical boron powder, and the particle size is 1-5 μm.

[0024] In some optional embodiments, the auxiliary fuel includes one or more of methanol, ethanol, unsymmetrical dimethylhydrazine, kerosene, glycerol, hydrazine, and methylhydrazine.

[0025] The low shear stress phase change gel propellant provided by the present invention uses metal fuel + auxiliary fuel as the gel propellant fuel. The fine particle size metal fuel can not only improve the stability of the gel propellant, but also significantly increase the combustion temperature and energy performance of the propellant. The standard theoretical specific impulse of the gel propellant can reach 250 s. Since the gel propellant provided by the embodiments of the present invention mainly constructs a stable three-dimensional network structure through the stacking effect of fine particle size metal fuel, the cross-linking effect of the gelling agent and the intermolecular force, restricts the flow of components, and forms a stable ADN gel propellant. Therefore, controlling the metal fuel in the gel propellant within a suitable dosage range is necessary for obtaining a gel propellant with stable performance and high energy density. If the proportion of metal fuel in the gel propellant is too low, the energy of the gel propellant will decrease so that it does not meet the usage requirements. If the proportion of metal fuel in the gel propellant is too high, too much metal fuel cannot be evenly dispersed in the gel propellant, the gel system is unstable, and even sedimentation occurs, resulting in insufficient combustion of the gel propellant, reduced combustion performance, and also a decrease in energy.

[0026] In some alternative embodiments, the gelling agent includes one or more of fumed silica, polyvinyl alcohol, carbomer, octadecanamide, polyacrylic acid, polyacrylamide, agar, and hydroxypropyl cellulose.

[0027] In some alternative embodiments, the functional aids include one or more of phosphoric acid, antioxidant H, ethylenediaminetetraacetic acid, Mg(NO3)2, Tween 80, citric acid, tartaric acid, and oleylamine.

[0028] In a second aspect, the embodiments of the present invention provide a preparation method of the above-mentioned low shear stress phase change gel propellant, including the following steps:

[0029] S1. Dissolve the oxidizer in water to obtain an oxidizer solution;

[0030] S2. Add the gelling agent and stir to mix until the gelling agent is completely dissolved or evenly dispersed;

[0031] S3. Continuously add the metal fuel, auxiliary fuel, and functional aids, mix until evenly dispersed, then heat and stir until a homogeneous sol is formed, and let it stand and cool naturally to room temperature to form the gel propellant.

[0032] The preparation method of the phase change gel propellant under lower shear stress provided by the present invention has a simple process and good safety, and has broad application prospects.

[0033] In some alternative embodiments, in step S2, the stirring speed is 500 - 1000 rpm, and the stirring time is 0.5 - 2 h.

[0034] In some optional embodiments, in step S3, the stirring speed in the dispersion and heating stage is 200 - 600 rpm, the heating temperature is 55 - 60 °C, and the heating time is 30 - 120 min.

[0035] In a third aspect, the embodiments of the present invention provide an application of the above low shear stress phase - changeable gel propellant in a solid - liquid combined engine and a gel engine.

[0036] The present invention will be further described below in conjunction with embodiments.

[0037] Embodiment 1

[0038] This embodiment provides a gel propellant that can undergo a phase change under a relatively low shear stress, and its formulation is shown in Table 1.

[0039] Table 1

[0040] Formulation composition Content / % ADN 60 Al powder 12.5 Glycerol 12.5 Water 10 Polyvinyl alcohol 3 Fumed silica 1 Ethylenediaminetetraacetic acid 0.5 <![CDATA[Mg(NO3)2]]> 0.5

[0041] The preparation method of the above gel propellant includes the following steps:

[0042] S1: Weigh each component according to the formulation design and set aside.

[0043] S2: At normal temperature and pressure, dissolve ADN in water to prepare a uniform ADN aqueous solution.

[0044] S3: Add polyvinyl alcohol and fumed silica to the ADN aqueous solution and disperse evenly at a rotation speed of 600 rpm.

[0045] S4: Add glycerol, aluminum powder, ethylenediaminetetraacetic acid, and Mg(NO3)2. After dispersing evenly, stir and heat to 60 °C at 400 rpm, and stop heating after 45 min of heating. After standing and cooling to room temperature, a gel propellant is formed.

[0046] After calculation, the theoretical specific impulse of the gel propellant provided in this embodiment is 2466.66 (N·s) / kg, the characteristic velocity is 1537.26 m / s, and the combustion flame temperature is 2713.8 K. After testing, the yield shear strength of the gel propellant is 45.39 Pa, that is, when the shear stress is greater than 45.39 Pa, the gel propellant begins to change from the gel state to the liquid state, and the viscosity of the propellant at a shear rate of 100 s -1 is 39.56 mPa·s.

[0047] Embodiment 2

[0048] This embodiment provides a gel propellant that can undergo a phase change under a relatively low shear stress, and its formulation is shown in Table 2.

[0049] Table 2

[0050] Formulation composition Content / % ADN 65 Al powder 7.5 Glycerol 7.5 Water 15 Polyvinyl alcohol 3 Fumed silica 1 Ethylenediaminetetraacetic acid 0.5 <![CDATA[Mg(NO3)2]]> 0.5

[0051] The preparation method of the above gel propellant comprises the following steps:

[0052] S1: Weigh each component according to the formulation design and set aside for later use;

[0053] S2: At normal temperature and pressure, dissolve ADN in water to prepare a homogeneous aqueous ADN solution;

[0054] S3: Add polyvinyl alcohol and fumed silica to the aqueous ADN solution and disperse evenly at a rotation speed of 600 rpm;

[0055] S4: Add glycerol, aluminum powder, ethylenediaminetetraacetic acid, and Mg(NO3)2. After dispersing evenly, stir and heat at 400 rpm to raise the temperature to 60 °C. The heating time is 45 min. After forming a homogeneous sol by dispersing evenly, stop heating. After standing and cooling to room temperature, it becomes a gel propellant.

[0056] Calculated, the theoretical specific impulse of the gel propellant provided in this example is 2401 (N·s) / kg, the characteristic velocity is 1481.26 m / s, and the combustion flame temperature is 2556.7 K. After testing, the yield shear strength of the gel propellant is 67.21 Pa, that is, when the shear stress is greater than 67.21 Pa, the gel propellant begins to transform from the gel state to the liquid state, and the viscosity of the propellant at a shear rate of 100 s -1 is 40.39 mPa·s.

[0057] Example 3

[0058] This example provides a gel propellant that can undergo a phase change under a lower shear stress, and its formulation is shown in Table 3.

[0059] Table 3

[0060] Formulation composition Content / % ADN 70 Al powder 2.5 Glycerol 2.5 Water 20 Polyvinyl alcohol 3 Fumed silica 1 Ethylenediaminetetraacetic acid 0.5 <![CDATA[Mg(NO3)2]]> 0.5

[0061] The preparation method of the above gel propellant comprises the following steps:

[0062] S1: Weigh each component according to the formulation design and set aside for later use;

[0063] S2: At normal temperature and pressure, dissolve ADN in water to prepare a homogeneous aqueous ADN solution;

[0064] S3: Add polyvinyl alcohol and fumed silica to the aqueous ADN solution and disperse evenly at a rotation speed of 600 rpm;

[0065] S4: Add glycerol, aluminum powder, ethylenediaminetetraacetic acid, and Mg(NO3)2. After dispersing evenly, stir and heat at 400 rpm until the temperature rises to 60 °C. The heating time is 45 min. Stop heating after forming a homogeneous sol by uniform dispersion. After standing and cooling to room temperature, a gel propellant is formed.

[0066] Calculated, the theoretical specific impulse of the gel propellant provided in this example is 2352 (N·s) / kg, the characteristic velocity is 1463.68 m / s, and the combustion flame temperature is 2461.0 K. After testing, the yield shear strength of the gel propellant is 62.39 Pa, that is, when the shear stress is greater than 62.39 Pa, the gel propellant begins to transform from the gel state to the liquid state, and the propellant viscosity at a shear rate of 100 s -1 is 43.74 mPa·s.

[0067] Example 4

[0068] This example provides a gel propellant that can undergo a phase change under a lower shear stress, and its formulation is shown in Table 4.

[0069] Table 4

[0070] Formulation composition Content / % AND 70 Mg powder 2.5 Glycerol 2.5 Water 20 Polyvinyl alcohol 3 Fumed silica 1 Ethylenediaminetetraacetic acid 0.5 <![CDATA[Mg(NO3)2]]> 0.5

[0071] The preparation method of the above gel propellant includes the following steps:

[0072] S1: Weigh each component according to the formulation design and set aside;

[0073] S2: Under normal temperature and pressure, dissolve ADN in water to prepare a homogeneous ADN aqueous solution;

[0074] S3: Add polyvinyl alcohol and fumed silica to the ADN aqueous solution and disperse evenly at a rotation speed of 600 rpm;

[0075] S4: Add glycerol, magnesium powder, ethylenediaminetetraacetic acid, and Mg(NO3)2. After dispersing evenly, stir and heat at 400 rpm until the temperature rises to 60 °C. The heating time is 45 min. Stop heating after forming a homogeneous sol by uniform dispersion. After standing and cooling to room temperature, a gel propellant is formed.

[0076] Calculated, the theoretical specific impulse of the gel propellant provided in this example is 2122.92 (N·s) / kg, the characteristic velocity is 1312.47 m / s, and the combustion flame temperature is 1905.6 K. After testing, the yield shear strength of the gel propellant is 59.61 Pa, that is, when the shear stress is greater than 59.61 Pa, the gel propellant begins to transform from the gel state to the liquid state, and the propellant viscosity at a shear rate of 100 s -1 is 42.64 mPa·s.

[0077] Example 5

[0078] This embodiment provides a gel propellant that can undergo a phase change under a relatively low shear stress, and its formulation is shown in Table 5.

[0079] Table 5

[0080] Formulation composition Content / % ADN 60 Mg powder 25 Water 10 Polyvinyl alcohol 3 Fumed silica 1 Ethylenediaminetetraacetic acid 0.5 <![CDATA[Mg(NO3)2]]> 0.5

[0081] The preparation method of the above gel propellant includes the following steps:

[0082] S1: Weigh each component according to the formulation design and set aside.

[0083] S2: At normal temperature and pressure, dissolve ADN in water to prepare a homogeneous aqueous ADN solution.

[0084] S3: Add polyvinyl alcohol and fumed silica to the aqueous ADN solution and disperse evenly at a rotation speed of 600 rpm.

[0085] S4: Add magnesium powder, ethylenediaminetetraacetic acid, and Mg(NO3)2. After dispersing evenly, stir and heat to 60 °C at 400 rpm. The heating time is 45 min. After forming a homogeneous sol by dispersing evenly, stop heating. After standing and cooling to room temperature, it becomes a gel propellant.

[0086] After calculation, the theoretical specific impulse of the gel propellant provided in this embodiment is 2393.16 (N·s) / kg, the characteristic velocity is 1472.92 m / s, and the combustion flame temperature is 2187.0 K. After testing, the yield shear strength of the gel propellant is 73.12 Pa, that is, when the shear stress is greater than 73.12 Pa, the gel propellant begins to transform from the gel state to the liquid state, and the viscosity of the propellant at a shear rate of 100 s -1 is 41.65 mPa·s.

[0087] Example 6

[0088] This embodiment provides a gel propellant that can undergo a phase change under a relatively low shear stress, and its formulation is shown in Table 6.

[0089] Table 6

[0090] Formulation composition Content / % ADN 60 Al powder 12.5 Glycerol 12.5 Water 10 Hydroxypropyl cellulose 2 Octadecanamide 2 Ethylenediaminetetraacetic acid 0.5 <![CDATA[Mg(NO3)2]]> 0.5

[0091] The preparation method of the above gel propellant includes the following steps:

[0092] S1: Weigh each component according to the formulation design and set aside.

[0093] S2: At normal temperature and pressure, dissolve ADN in water to prepare a homogeneous aqueous ADN solution.

[0094] S3: Add hydroxypropyl cellulose and octadecanamide to the ADN aqueous solution and disperse evenly at a rotation speed of 800 rpm;

[0095] S4: Add glycerol, aluminum powder, ethylenediaminetetraacetic acid, and Mg(NO3)2. After dispersing evenly, stir and heat to 55 °C at 400 rpm. The heating time is 40 min. Stop heating after forming a homogeneous sol by dispersing evenly. After standing and cooling to room temperature, a gel propellant is formed.

[0096] Calculated, the theoretical specific impulse of the gel propellant provided in this example is 2469.75 (N·s) / kg, the characteristic velocity is 1538.74 m / s, and the combustion flame temperature is 2723.8 K. After testing, the yield shear strength of the gel propellant is 55.26 Pa, that is, when the shear stress is greater than 55.26 Pa, the gel propellant begins to change from the gel state to the liquid state, and the viscosity of the propellant at a shear rate of 100 s -1 is 42.14 mPa·s.

[0097] Example 7

[0098] This example provides a gel propellant that can undergo a phase change under a lower shear stress, and its formula is shown in Table 7.

[0099] Table 7

[0100]

[0101]

[0102] The preparation method of the above gel propellant includes the following steps:

[0103] S1: Weigh each component according to the formula design and set aside;

[0104] S2: Dissolve ADN in water under normal temperature and pressure to prepare a homogeneous ADN aqueous solution;

[0105] S3: Add hydroxypropyl cellulose and octadecanamide to the ADN aqueous solution and disperse evenly at a rotation speed of 800 rpm;

[0106] S4: Add glycerol, aluminum powder, phosphoric acid, and Tween 80. After dispersing evenly, stir and heat to 55 °C at 400 rpm. The heating time is 40 min. Stop heating after forming a homogeneous sol by dispersing evenly. After standing and cooling to room temperature, a gel propellant is formed.

[0107] Calculated, the theoretical specific impulse of the gel propellant provided in this embodiment is 2470.35 (N·s) / kg, the characteristic velocity is 1536.37 m / s, and the combustion flame temperature is 2724.1 K. After testing, the yield shear strength of the gel propellant is 68.69 Pa, that is, when the shear stress is greater than 68.69 Pa, the gel propellant begins to transform from the gel state to the liquid state, and the viscosity of the propellant at a shear rate of 100 s -1 is 43.21 mPa·s.

[0108] Example 8

[0109] This embodiment provides a gel propellant that can undergo a phase change under a lower shear stress, and its formulation is shown in Table 8.

[0110] Table 8

[0111]

[0112]

[0113] The preparation method of the above gel propellant includes the following steps:

[0114] S1: Weigh each component according to the formulation design and set aside;

[0115] S2: Under normal temperature and pressure, dissolve ADN in water to prepare a uniform ADN aqueous solution;

[0116] S3: Add hydroxypropyl cellulose to the ADN aqueous solution and disperse it evenly at a rotation speed of 800 rpm;

[0117] S4: Add glycerol, aluminum powder, ethylenediaminetetraacetic acid, and Mg(NO3)2. After dispersing evenly, stir and heat to 55 °C at 400 rpm. The heating time is 40 min. After forming a uniform sol, stop heating and let it stand and cool to room temperature to obtain the gel propellant.

[0118] Calculated, the theoretical specific impulse of the gel propellant provided in this embodiment is 2469.63 (N·s) / kg, the characteristic velocity is 1538.96 m / s, and the combustion flame temperature is 2722.4 K. After testing, the yield shear strength of the gel propellant is 57.81 Pa, that is, when the shear stress is greater than 57.81 Pa, the gel propellant begins to transform from the gel state to the liquid state, and the viscosity of the propellant at a shear rate of 100 s -1 is 46.23 mPa·s.

[0119] Comparative Example 1

[0120] This comparative example provides a gel propellant, and its formulation is shown in Table 9.

[0121] Table 9

[0122]

[0123]

[0124] The preparation method of the above gel propellant includes the following steps:

[0125] S1: Weigh each component according to the formulation design and set aside;

[0126] S2: Dissolve ADN in water under normal temperature and pressure to prepare a uniform aqueous ADN solution;

[0127] S3: Add polyvinyl alcohol and fumed silica to the aqueous ADN solution and disperse evenly at a speed of 600 rpm;

[0128] S4: Add glycerol, aluminum powder, ethylenediaminetetraacetic acid, and Mg(NO3)2. After dispersing evenly, stir and heat to 40 °C at 400 rpm. The heating time is 45 min. Stop heating after forming a uniform sol by dispersing evenly. Let it stand and cool to room temperature to obtain the gel propellant.

[0129] Compared with Example 1, the temperature during the preparation of the gel propellant in Comparative Example 1 was 40 °C, and the result was that the gel system could not be dispersed evenly and a uniform gel could not be prepared.

[0130] Comparative Example 2

[0131] This comparative example provides a gel propellant, and its formulation is shown in Table 10.

[0132] Table 10

[0133]

[0134]

[0135] The preparation method of the above gel propellant includes the following steps:

[0136] S1: Weigh each component according to the formulation design and set aside;

[0137] S2: Dissolve ADN in water under normal temperature and pressure to prepare a uniform aqueous ADN solution;

[0138] S3: Add hydroxypropyl cellulose and octadecanamide to the aqueous ADN solution and disperse evenly at a speed of 800 rpm;

[0139] S4: Add glycerol, phosphoric acid, and Tween 80. After dispersing evenly, stir and heat to 55 °C at 400 rpm. The heating time is 40 min. Stop heating after forming a uniform sol by dispersing evenly. Let it stand and cool to room temperature to obtain the gel propellant.

[0140] After calculation, the theoretical specific impulse of the gel propellant provided in this comparative example is 2037.42 (N·s) / kg, the characteristic velocity is 1291.13 m / s, and the combustion flame temperature is 1601.5 K. Compared with Example 7, the theoretical specific impulse is reduced by 432 (N·s) / kg, and the combustion temperature is reduced by 1432.97 K. After testing, the yield shear strength of the gel propellant is 86.37 Pa, and the viscosity of the propellant at a shear rate of 100 s -1 is 87.61 mPa· at the shear rate.

[0141] Compared with Example 7, the yield strength and viscosity of the gel propellant in Comparative Example 2 are higher than those in Example 7. The result is that the overall energy of the gel propellant in Comparative Example 2 is greatly reduced and the viscosity is increased, which is not conducive to its use in the engine.

[0142] The above are only the preferred embodiments of the present invention and are not intended to limit the present invention. For those skilled in the art, various changes and modifications can be made to the present invention. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. A low shear stress phase change gel propellant, characterized in that: Calculated by mass percentage, it includes the following components: Oxidant: 60%-70%, metal fuel: 2%-27.5%, auxiliary fuel: 0%-15%, water: 10%-20%, gelling agent: 2%-5% and functional additives: 0.5%-3%.

2. The low shear stress phase change gel propellant according to claim 1, characterized in that: The oxidizing agent includes ammonium dinitramide.

3. The low shear stress phase change gel propellant according to claim 1, characterized in that: The metal fuel includes Al powder, Mg powder, Mg-Al alloy powder, Li-Al alloy powder, and spherical boron powder. Preferably, the particle size of the metal fuel is 1-5 μm.

4. The low shear stress phase change gel propellant according to claim 1, characterized in that: The auxiliary fuel includes one or more of methanol, ethanol, unsymmetrical dimethylhydrazine, kerosene, glycerol, hydrazine, and methylhydrazine.

5. The low shear stress phase change gel propellant according to claim 1, characterized in that: The gelling agent comprises one or more of fumed silica, polyvinyl alcohol, carbomer, octadecylamide, polyacrylic acid, polyacrylamide, agar, and hydroxypropyl cellulose.

6. The low shear stress phase change gel propellant according to claim 1, characterized in that: The functional additives include one or more of phosphoric acid, antioxidant H, ethylenediaminetetraacetic acid, Mg(NO3)2, Tween 80, citric acid, tartaric acid, and oleylamine.

7. A method for preparing a low shear stress phase change gel propellant according to any one of claims 1 to 6, characterized in that: The following steps are involved: S1. dissolving an oxidant in water to obtain an oxidant solution; S2, adding the gelling agent and stirring and mixing until the gelling agent is completely dissolved or evenly dispersed; S3. Continue to add metal fuel, auxiliary fuel and functional additives, mix until evenly dispersed, heat and stir until a uniform sol is formed, and let stand and cool naturally to room temperature to form a gel propellant.

8. The preparation method according to claim 7, characterized in that: In step S2, the stirring speed is 500-1000 rpm, and the stirring time is 0.5-2 h.

9. The preparation method according to claim 7, characterized in that: In step S3, the stirring speed in the dispersion and heating stage is 200-600 rpm, the heating temperature is 55-60° C., and the heating time is 30-120 min.

10. Use of the low shear stress phase change gel propellant according to any one of claims 1 to 6 or the low shear stress phase change gel propellant prepared by the preparation method according to any one of claims 7 to 9 in a solid-liquid combination engine or a gel engine.

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