EP1896718A1

EP1896718A1 - Gel-type fuel based drive device and method for supplying fuel

Info

Publication number: EP1896718A1
Application number: EP06762104A
Authority: EP
Inventors: Helmut Konrad Ciezki; Klaus Madlener; Oskar Haidn
Original assignee: Deutsches Zentrum fuer Luft und Raumfahrt eV
Current assignee: Deutsches Zentrum fuer Luft und Raumfahrt eV
Priority date: 2005-06-30
Filing date: 2006-06-21
Publication date: 2008-03-12
Also published as: WO2007003270A1; DE102005030437B4; IL188370A; US20090165437A1; IL188370A0; US8033095B2; DE102005030437A1

Abstract

The invention relates to a gel-type fuel based drive device, in particular, for a missile, which comprises at least one tank for gel-type fuel, a combustion chamber and a fuel supply device for the combustion chamber. The aim of the invention is to produce said device such that is has a simple construction. As a result, at least one radiation impinging device which is used to impinge on gel-type fuel by means of electromagnetic radiation and/or at least one heating device which is used to warm gel-type fuel is provided in order improve the fluidity.

Description

Drive device based on gel-type fuel and method for fuel delivery

The invention relates to a drive device based on gel fuel, in particular for a missile, comprising at least one tank for gel fuel, a combustion chamber and a supply means of fuel to the combustion chamber.

The invention further relates to a method for fuel delivery in a drive device.

From US 5,133,183 A a drive system is known in which a gel-shaped oxidant is used.

From US 3,032,979 a rocket motor is known, which is driven by means of a gelatinous mono-fuel.

Gel propellants and their applications are disclosed in the articles "An Overlook of Investigations on Gel Fuels for Ramjet Applications" by HK Ciezki and B. Natan, International Symposium on Airbrushing Engines, ISABE 2005, Munich, for publication in September 2005, " Theoretical approaches to the influence of non-linear material properties of propellants on the flow in injectors "by HK Ciezki et al., 33" * International Annual

Conference of ICT, Karlsruhe, 2002 or "The Status of gel propellants in year 2000" by B. Natan and S. Rahimi, in Combustion of Energetic Materials, editors KK Kuo, L. de Luca, Boca Raton, 2001. Gel-shaped fuels have the advantage that they are solid under normal conditions and are flowable under shear stresses. Because of these characteristics, an adjustable drive device can be provided. In comparison, solid propellants are storable and have good handling, but the combustion after ignition is no longer stoppable and usually corresponding engines are also not regulated. In turn, liquid engines are controllable, but the sensitivity to leaks is very high and a lot of effort is required in terms of production. By driving devices based on gel fuels, the positive properties of solid and liquid drives can be combined.

The invention has for its object to provide a drive device of the type mentioned above, which is simple in construction.

This object is achieved in the above-mentioned drive device according to the invention in that at least one Strahlungsbeaufschlagungs- device for applying gelatinous fuel with electromagnetic radiation and / or at least one heating device for heating gelförmigem fuel is provided to improve the flow behavior.

Gel-shaped propellants show a non-Newtonian flow behavior, ie the shear viscosity is shear rate-dependent and the extensional viscosity is strain-dependent. According to the invention, a radiation application device and / or heating device is provided, via which by non-mechanical means Energy input the shear viscosity and / or Dehnviskosität of the fuel is reducible. This improves its flow behavior. It can thus optimize the promotion of fuel, the jet breakup and possibly also its evaporation and combustion. In turn, the fuel processing and / or Oxidatoraufbereitung can be optimized to achieve an optimized combustion management. The reduction of the extensional viscosity becomes relevant, for example, with pipe constrictions.

By reducing the viscosity of a fuel delivery can be achieved with lower discharge pressures. This reduces the overall mass of the application (such as a missile). In particular, for example, the tank can be formed with a smaller wall thickness. In turn, fuel consumption can be reduced or longer ranges can be achieved. It is also possible to provide drive devices with small dimensions, such as for an ejection seat.

By the application of radiation and / or heating (in particular direct thermal heating or induction heating), the temperature in the gel fuel can be increased in order to lower its viscosity. By

Radiation exposure via electromagnetic radiation can be broken with appropriate frequency selection bonds in the gelling agent scaffold to lower the viscosity.

By radiation exposure, an energy input from the outside can be carried out without contact and directly. It can be done within short delivery times and within a short period of time achieve a viscosity reduction. In turn, lead times can be lowered. For example, radiation is applied immediately before or at the start of an application such as an airborne body.

It is possible, for example, that a carrier of the missile provides the energy for the radiation or heating of the gel fuel. The wearer may himself be mobile and in particular himself a flying body. The carrier can also be stationary.

In principle, it is also possible that the energy generating device is arranged to provide the energy for exposing or heating the gelatinous fuel in the missile.

The gel fuel may be a gel fuel and / or a gelled oxidizer. It may also be a combination of different fuels, of which at least one is gel-like or a combination of different oxidizing agents, at least one of which is gel-like.

It is favorable if at least one radiation application device and / or at least one heating device is assigned to the at least one tank. As a result, the viscosity can be reduced in a correspondingly large volume range of gelatinous fuel. This in turn makes it possible to reduce the delivery pressure for the delivery of fuel to the combustion chamber. In particular, the at least one radiation application device and / or at least one heating device is arranged on the at least one tank. As a result, radiation exposure or heating of gel fuel in the tank can be achieved in a simple manner. In this case, the entire volume of the tank can be subjected to radiation or heated or only a partial area.

Furthermore, it is favorable if at least one radiation application device and / or at least one heating device is assigned to one or more supply lines of the at least one tank to the combustion chamber. This can facilitate the promotion of the tank to the combustion chamber. It can thereby also supply fuel to the combustion chamber, which has improved spraying and evaporation properties.

In particular, at least one radiation application device and / or at least one heating device is arranged on one or more supply lines of the at least one tank to the combustion chamber. As a result, the viscosity of fuel guided in the at least one supply line can be reduced in a simple manner.

It can also be provided that at least one radiation application device and / or at least one heating device is assigned to an injection region for fuel in the combustion chamber. This can reduce the viscosity of fuel injected into the combustion chamber. This makes it possible to optimize the spraying behavior and the evaporation behavior and, concomitantly, the combustion behavior. In particular, at least one radiation application device and / or at least one heating device is arranged at an injection region for fuel into the combustion chamber in order to allow an energy input into the gel-shaped fuel in order to reduce the viscosity.

Conveniently, the at least one radiation application device and / or at least one heating device is designed so that a volume range of gel fuel can be acted upon by electromagnetic radiation and / or heated. As a result, the viscosity in the gel-like fuel can be effectively reduced.

In a simple embodiment, the supply device comprises at least one piston device for conveying gel-type fuel from the at least one tank to the combustion chamber.

It is favorable if the radiation of the at least one radiation application device is adjusted in terms of frequency and / or intensity so that the temperature in the gel-shaped fuel can be increased. In the case of temperature-sensitive gels, a temperature increase is usually accompanied by a reduction in the viscosity.

It can also be favorable if the radiation of the at least one radiation application device is admitted in terms of frequency and / or intensity in such a way that the yield point in the gel-shaped fuel can be lowered. As a result, the conveying properties of the fuel can be improved. It may also be favorable if the radiation of the at least one radiation application device is adjusted in terms of frequency and / or intensity so that bonds in the gelling agent framework can be broken. Also in this way the viscosity can be lowered. This is particularly advantageous if the corresponding gel-like fuel is a low

Temperature sensitivity has. Through targeted frequency adjustment, resonance frequencies in the gel can be stimulated to break up intermolecular bonds.

In particular, the at least one radiation application device comprises at least one transmitter. The electromagnetic radiation emitted by the transmitter makes it possible to lower the viscosity in the gel-like fuel.

In particular, the at least one radiation application device radiates in the microwave range, that is to say in a wavelength range between approximately 1 mm and 30 cm (in the frequency range from 1 GHz to 30 GHz). As a result, the viscosity in the gel fuel can be reduced.

It is favorable if the gel-shaped fuel comprises one or more polar substances. Gelled propellants are usually formed by gelling a precursor with a gelling agent. The starting material (the "actual" fuel) may itself be a polar substance or the gelling agent may comprise a polar substance or adjuvants of poiar character may be provided. In the case of gaseous propellants which comprise one or more polar substances, it is generally possible to achieve a high temperature sensitivity, that is to say a reduction in viscosity on heating. The invention is further based on the object to provide a method for fuel delivery in a drive device.

This object is achieved in that the flow behavior of the fuel is influenced by non-mechanical energy input.

The method according to the invention has the advantages already explained in connection with the drive device according to the invention. The non-mechanical energy input can improve the flow behavior of a fuel with Newtonian or non-Newtonian behavior.

Further advantageous embodiments have also already been explained in connection with the drive device according to the invention.

Due to the non-mechanical energy input in particular the temperature is increased in the example gel-shaped fuel. This can be done for example by thermal heating or by Strahlungsbeaufschlagung.

In particular, the shear viscosity and / or elongational viscosity is lowered by the non-mechanical energy input. As a result, a good delivery behavior can be achieved, in particular under reduced delivery pressures.

It is advantageous if the energy input erfoigt by electromagnetic radiation. As a result, a large volume range can be applied directly and directly in order to reduce the viscosity in this volume range. The admission can be fast and within a short time Period so that the activation is controllable. By appropriate radiation adjustment, it is possible to excite certain frequencies in order to break up bonds in the gelling agent framework.

For example, the energy input is by microwave radiation to lower the viscosity.

It is favorable if a non-mechanical energy input into the fuel takes place in a tank. As a result, the viscosity of fuel in the tank can be lowered, in turn, to facilitate the promotion of fuel from the tank to a combustion chamber.

It can also be provided that non-mechanical energy input into the fuel takes place in a supply line from a tank to a combustion chamber. As a result, the promotion of fuel in the supply line can be improved. Furthermore, it is possible to positively promote the spray behavior and evaporation behavior of the fuel when coupled into the combustion chamber.

For the same reason, it is beneficial to have non-mechanical energy input into fuel in an injection area for injecting fuel into the combustion chamber.

In particular, the fuel is a gel fuel. Under fuel is generally understood fuel and / or Oxidationsmittei. The following description of preferred embodiments is used in conjunction with the drawings for a more detailed explanation of the invention. Show it:

Figure 1 is a schematic representation of a missile with an embodiment of a drive device according to the invention;

FIG. 2 shows the curve of the dynamic shear viscosity η versus the shear rate γ of a paraffin gel at different temperatures;

Figure 3 shows the deformation γ of a paraffin gel as a function of the applied shear stress τ for different temperatures (yield point) and

Figure 4 shows the temperature dependence of the viscosity of pure paraffin.

An exemplary embodiment of a drive device according to the invention, which is shown schematically in FIG. 1 and designated therein by 10, is arranged on a missile 12 such as a rocket.

The driving device 10, which is particularly a thrust generating device, is a gel-propelled gel-based gel driving device. The fuel may be the fuel and / or the oxidizer. The gel fuel may comprise a single fuel component (monopropellant) or it may be a composition of several fuel components (such as a bi-propellant). The fuel may be monergol, diergol, triergol etc. or hypergol. For storage of the gel-like fuel (at least) a tank 14 is provided, is received in the gel-shaped fuel 16. For several fuel components, a corresponding number of tanks may be provided.

The drive device 10 comprises a combustion chamber 18, in which, if the fuel is gel-shaped, this gel-shaped fuel is burned with the introduction of an (optionally gel-shaped) oxidizing agent. The combustion chamber 18 may be associated with an ignition device (not shown in the drawing).

The combustion chamber 18 has an injection region 20, via which fuel can be injected into the combustion chamber 18. Furthermore, oxidizing agent can be injected into the combustion chamber 18 via the injection region 20.

The drive device 10 comprises a supply device, designated as a whole by 22, for supplying fuel to the combustion chamber 18 via the injection area 20. This supply device 22 has one or more supply lines 24, which between the (at least one) tank 14 and the injection area 20 of FIG Combustion chamber 18 are arranged.

The feeder 22 further includes a conveyor 26 for conveying the fuel from the tank 14 to the combustor 18. By way of example, the conveying device 26 has a piston device 28 with a piston 30 which is movable in the tank 14. The piston 30 allows fuel to be pressed into the supply line 24 and pressed through the supply line 24 to the combustion chamber 18. The piston 30 of the piston device 28 is driven by a drive 32.

The combustion chamber 18 may be arranged downstream of a thruster 34.

The drive device 10 works with gel fuel; the drive device 10 is a gel engine.

A gel is a medium that has a colloidal structural network that has a continuous matrix and completely penetrates the liquid phase.

On the basis of gel fuel propellable thrusters can be provided. In particular, small engines can be built. Geoid fuels behave like solids under normal environmental conditions and can therefore be easily stored and handled. Under pressure and shear stress they become fluid; this makes it possible to carry out a throughput control, which in turn allows thrust control. Furthermore, unlike liquid fuels, gaseous fuels allow multiple ignition. Gel fuel can be handled relatively safely and it can be a high insensitivity, for example, to achieve leakage or shelling. Propulsion devices based on gelled propellants have advantages of solids propulsion and liquid propulsion.

Gels are non-Newtonian fluids; Theological behavior is shear rate dependent and / or strain rate dependent as well as thixotropic. According to the invention (at least one) Strahlungsbeaufschlagungseinrichtung 36 and / or heating means is provided, via which the viscosity in gelförmigem fuel is herabiedrig to optimize the flow behavior of the gel fuel in particular with regard to promotion and / or Strahizerfall and / or evaporation and / or combustion.

In particular, an increase in the temperature in the gel-type propellant to reduce the viscosity takes place via the radiation-applying device 36 and / or the heating device.

FIG. 2 shows the behavior of the dynamic shear viscosity η versus the shear rate γ for an example of a gel-type fuel, namely paraffin gel. The paraffin gel is composed of paraffin, 7.5% thixatrol ST and 7.5% methyl isoamyl ketone (MIAK). The curve of the dynamic shear viscosity is shown for different temperatures; the upper curve 38 shows the course at a temperature of 25 ° C, the lower curve 40 the course at a temperature of 80 ⁰ C and the middle curve 42 the course at a temperature between these two temperatures. The shear-thinning behavior of the gel is first recognized: As the shear rate γ increases, the dynamic shear viscosity decreases.

Furthermore, one recognizes the influence of temperature on the dynamic shear viscosity: At higher temperatures, the viscosity is lower with the same shear rate. The increase in temperature in the gel-like fuel can be achieved, for example, by applying a microwave radiation to the gel-form fuel in the tank 14 via the radiation application device 36. For this purpose, the Strahlungsbeaufschlagungseinrichtung 36 comprises a microwave transmitter, which, for example, microwave radiation with

Wavelengths in the range of about 12 mm (frequency of about 2.5 GHz) radiates.

In this case, a volume region of the tank 14 is subjected to radiation. The volume range may be the total intake volume of the tank 14 or a portion thereof.

It can also be provided that the supply line or supply lines 24 are acted upon by a radiation application device 44 and / or by a heater in order to reduce the viscosity of fuel guided therein.

For the same reason, it can be provided that the injection area 20 is exposed to radiation or a heater is provided.

The Strahlungsbeaufschlagungseinrichtung 26 and 44 transmits electromagnetic radiation. It is thus possible to penetrate a large volume range in the gel-shaped fuel and thus to lower the viscosity in a large volume range.

In principle, it is also possible for a heating device to be used for direct thermal loading of the gel-form fuel or for induction heating to be provided. There may be a temperature increase in the gel fuel by radiation or by thermal heating. With temperature-sensitive gels, the associated increase in temperature can reduce the viscosity (in particular the shear viscosity and / or extensional viscosity).

It is also possible for bonds in the gelling agent framework of the fuel to be broken up by the radiation application and / or, for example, direct thermal heating. This also leads to a lowering of the viscosity. This mechanism is particularly relevant if the gel fuel has low temperature sensitivity.

It can be provided, in particular, that the radiation of the radiation impinging device 36 or 44 is adjusted in terms of frequency and / or intensity so that specific bindings are specifically excited in order to break them up.

According to the invention, a non-mechanical energy input takes place via radiation exposure and / or heating (for example via direct thermal heating or by induction heating, when the gel-shaped fuel can be heated in this way) into the gel-shaped fuel from outside. By electromagnetic radiation, this non-mechanical energy input can be performed without contact and directly. It can act on a large volume range of the gel fuel and thus a large

Heat volume area. Targeted excitation can break bonds in the gel framework. Overall, the viscosity can be reduced. This in turn reduces the effort for liquefying the gel by means of mechanical shear forces (FIG. 2). It will cause lower delivery pressure losses. The conveyor 26 can be formed with less power. In addition, the design effort is reduced because, for example, walls of the tank 14 can be formed with a smaller thickness.

The viscosity reduction according to the invention and the concomitant delivery pressure reduction make it possible to realize a weight saving. This results in the missile 12 to lower fuel consumption and larger flight ranges.

It is also possible, for example, for a viscosity reduction via radiation application and / or direct thermal heating to take place at or directly before an injection process at an injection area 20. As a result, the start preparation time for the missile 12 can be reduced.

The reduction in viscosity, in particular by exposure to radiation, has the advantage that it can take place within a short time. The reduction in viscosity can be carried out, for example, immediately before use or at start-up and even in short periods. This allows a high level of operational readiness for the missile 12.

By raising the temperature in a gel (for example by exposure to electromagnetic radiation or by thermal heating), the yield point for certain gels can also be lowered. The yield point is the value or range of shear stress to which a gel behaves as a solid. To make gel flow, the flow limit must be exceeded.

FIG. 3 shows the deformation γ for the above-mentioned paraffin gel as a function of the applied shear stress τ for different temperatures. The temperature values are indicated on the respective curves. It can be seen that the yield point at 0 ^° C. is about 78 Pa, whereas it is about 0.1 Pa at 80 ^° C. Increasing the temperature of this gel reduces the flow limit (which is defined here by the shear stress at the bend in the curve).

This means that the yield point is significantly reduced by increasing the temperature of this gel. For this reason too, the flow properties in gel-form fuel can be improved by exposure to radiation or direct heating.

The basic building material of the above-mentioned paraffin gel is paraffin, which is, to a good approximation, a Newtonian fluid. The paraffin gel as a gel fuel is achieved by gelling the paraffin with a gelling agent. Liquid paraffin shows a strong temperature dependence of the viscosity η (Figure 4). As the temperature increases, the viscosity decreases.

This temperature dependence of the viscosity of the gel base material also contributes to the fact that the viscosity of the gel decreases with temperature increase. According to the invention, a method is provided for fuel delivery in a drive device (for example on the basis of a fuel with non-Newtonian deformation and flow properties), in which the viscosity of the fuel is reduced by non-mechanical energy input. The non-mechanical energy input takes place in particular by exposure to electromagnetic radiation.

It is possible to reduce the viscosity substantially over the entire shear rate range. In particular, this viscosity reduction is caused by a temperature increase. For certain gels, the yield point can also be reduced. Overall, the delivery cost for the gel-shaped fuel can be reduced, which in turn reduces the total mass of the missile 12.

According to the invention, a drive device can be provided which is in particular controllable. This drive device 10 or thrust generating device can be used in connection with missiles 12, underwater rockets and the like. It can be used for hybrid rockets in which only one component is gelled, or for ramjet drives. It can also be used in conjunction with thrust vector control engines, bearing control engines (which, for example, generate thrust), and so on. The process according to the invention can also be used in connection with solid cryogenic drives (slushed hydrogen, etc.). For example, ejection seats can also be equipped with a corresponding drive device. It can also equip other systems that require a variable thrust. The energy for the irradiation and / or heating is provided by an energy generating device, which may be integrated into the missile 12 or is arranged externally. For example, the energy generating device is provided on a support for the missile 12. This carrier may be stationary or mobile. In particular, the corresponding energy is then coupled into the drive device 10 before the start, in order to improve the flow behavior of the gel-form fuel for the start and for the flight phase following the start.

Claims

PATENT CLAIMS

1. Drive device based on gel-type propellant (16), in particular for a missile (12), comprising at least one tank (14) for gelled propellant (16), a combustion chamber (18) and a supply device (22) of fuel to the combustion chamber (18 ), characterized in that at least one radiation application device (36; 44) is provided for impinging gel-form fuel (16) with electromagnetic radiation and / or at least one heating device for heating gel-form fuel (16) increases the flow behavior improve.

2. Drive device according to claim 1, characterized in that at least one Strahlungsbeaufschlagungseinrichtung (36; 44) and / or at least one heating device is associated with the at least one tank (14).

3. Drive device according to claim 1 or 2, characterized in that at least one Strahlungsbeaufschlagungseinrichtung (36; 44) and / or at least one heating device to the at least one tank (14) is arranged.

4. Drive device according to one of the preceding claims, characterized in that at least one Strahlungsbeaufschlagungsein- direction (44) and / or at least one heating device of one or more supply lines (24) of the at least one tank (14) is associated with the combustion chamber (18).

5. Drive device according to one of the preceding claims, characterized in that at least one Strahlungsbeaufschlagungsein- direction (44) and / or at least one heating device on one or more supply lines (24) of the at least one tank (14) to the combustion chamber (18) is arranged ,

6. Drive device according to one of the preceding claims, characterized in that an injection area (20) for fuel in the combustion chamber (18) at least one Radungsbeaufschlagungsein- direction (44) and / or at least one heating device is assigned.

7. Drive device according to one of the preceding claims, characterized in that at an injection area (20) for fuel in the combustion chamber (18) at least one Strahlungsbeaufschlagungsein- direction (44) and / or at least one heating device is arranged.

8. Drive device according to one of the preceding claims, characterized in that the at least one Strahlungsbeaufschlagungs- device (36; 44) and / or at least one heating device is designed so that a volume range of gel fuel can be acted upon by electromagnetic radiation and / or heated ,

9. Drive device according to one of the preceding claims, characterized in that the supply device (22) comprises at least one piston device (28) for conveying gelförmigem fuel from the at least one tank (14) to the combustion chamber (18).

10. Drive device according to one of the preceding claims, characterized in that the radiation of the at least one radiation impinging device (36; 44) with respect to frequency and / or intensity is set so that the temperature in the gel-shaped fuel (16) can be increased.

11. Drive device according to one of the preceding claims, characterized in that the radiation of the at least one radiation impinging device (36; 44) with respect to frequency and / or intensity is adjusted so that the yield point in the gel-shaped fuel (16) can be lowered.

12. Drive device according to one of the preceding claims, characterized in that the radiation of the at least one radiation impinging device (36; 44) is adjusted in terms of frequency and / or intensity so that bonds in the gelling agent framework of the gel fuel are rupturable.

13. Drive device according to one of the preceding claims, characterized in that the at least one Strahlungsbeaufschlagungs- device (36; 44) comprises at least one transmitter.

14. Drive device according to one of the preceding claims, characterized in that the at least one Strahlungsbeaufschlagungs- device (36; 44) radiates in the microwave range.

15. Drive device according to one of the preceding claims, characterized in that the gel-shaped fuel comprises one or more polar substances.

16. A method for fuel delivery in a drive device in which the flow behavior of the fuel is influenced by non-mechanical energy input.

17. The method according to claim 16, characterized in that the temperature in the fuel is increased by non-mechanical energy input.

18. The method according to claim 16 or 17, characterized in that the shear viscosity and / or elongational viscosity is lowered by the non-mechanical energy input.

19. The method according to any one of claims 16 to 18, characterized in that the energy input is effected by electromagnetic radiation.

20. The method according to any one of claims 16 to 19, characterized in that the energy input is effected by microwave radiation.

21. The method according to any one of claims 16 to 20, characterized in that a non-mechanical energy input into the fuel takes place in a tank.

22. The method according to any one of claims 16 to 21, characterized in that a non-mechanical energy input into the fuel takes place in a supply line from a tank to a combustion chamber.

23. The method according to any one of claims 16 to 22, characterized in that a non-mechanical energy input into the fuel takes place in an injection area for the injection of fuel into a combustion chamber.

24. The method according to any one of claims 16 to 23, characterized in that the fuel is a gel fuel.

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