GB1568238A - Rocket propulsion units - Google Patents

Description

(54) IMPROVEMENTS IN ROCKET PROPULSION UNITS (71) We, MEssERscHMíTT-BöLKow- 'BLOHM Gesellschaft mit beschränkter Hafstung, of 8000 Mtinchen, German Federal Republic a Company organised and existing under the laws of the German Federal Republic, do hereby declare the invention for which we pray that a Patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement:- This invention relates to a rocket propul sion unit having an electrical generator serving to supply power to a missile or the like with which the propulsion unit is associated. The propellant gases being used to power the generator.

According to this invention there is pro vided a rocket propulsion unit incorporating a magneto hydrodynamic electrical generator arranged to convert a part of the energy in the propellant gas stream to electrical energy the generator being arranged annularly around the throat of the combustion nozzle chamber. It has been found that the electrical energy required on board a missile is moder ate in relation to the power output of the propulsion unit and the high gas flow speed from the propulsion gas stream render com paratively weak magnetic fields sufficient.

The direction of flow of the propulsion gas stream is thus only slightly disturbed.

A magneto hydrodynamic (MHD) genera tor has no moving parts, is insensitive to high acceleration forces occurring in missiles and owing to the high temperatures of the propulsion gases (approximately 3500 K), the Carnot efficiency is high.

The MHD generator is advantageously arranged annularly around the throat zone of the propulsion nozzle at the zone where the maximum propulsion gas flow speed occurs.

The necessary magnetic fields are pre ferably produced by means of permanent magnets. For protection from the high propulsion gas temperatures it is of advantage if the MMD generator is provided with cooling channels carrying a flow of coolant which may be ambient air or a flow of liquid rocket propellant.

A rocket propulsion unit according to the invention embodying an MHD generator and intended for use in a rocket-propelled missile is shown by way of an example in the accompanying drawings.

In the drawings: Figure 1 shows a rocket propulsion unit with an electrical MMD generator, Figure 2 is a longitudinal section through part of the propulsion unit and generator, and Figure 3 is a cross section through the generator.

A rocket propulsion unit according to the invention is shown schematically with an electrical power supply generator intended for a rocket propelled missile in Figure 1.

As shown an MMD generator 2 is arranged annularly around the nozzle throat zone 1.2 of a rocket propulsion unit 1. The propellants are injected into the combustion chamber 1.1 of the rocket propulsion unit 1 through pipes 3, 4 and these propellants undergo combustion at temperatures of about 3,500 K in the combustion chamber.

At this temperature the combustion products ionize producing a plasma having relatively good electrical conductivity. To increase the conductivity of the plasma further it is seeded with a material for example with about 1 mol % cesium or potassium, through a conduit 5.

The electrical conductance of the plasma emerging from the combustion chamber 1.1 is then about 100 S/m. The particle speed of the plasma, in this zone, is about 1000 m/s.

The energy extracted by the generator 2, through the electric feed line 6 for supply of current to the missile is about 1 to 2% of the driving power of the rocket propulsion unit.

For this reason magnetic flux densities of about 0 5 to 1 Tesla which can be supplied by permanent magnets, are sufficient for the deflection of the ionized particles from the gas stream in the narrowest zone of the nozzle throat, 1.2.

Figure 2 shows the arrangement of the electrodes 8 and 9, and permanent magnets 7.1 and 7.2 which are in two sections. The electrodes 8 and 9 are subdivided into smaller -separate segments 8.1, 8.2, 8.3, 8.4 and 9.1, 9.2, 9.3, 9.4 to reduce Hall-effect losses.

Cooling ducts 10 extend longitudinally through the generator 2 and are interconnected where the rocket propellants are used as coolantior open at each end if air flow due to motion is used as coolant.

The arrangement of the cooling channels 10 and magnets 7.1 and 7.2 is shown more clearly in Figure 3. The permanent magnets 7.1 and 7.2 produce a magnetic flux perpendicular to the electrodes 8 and 9 and perpendicular to the direction of flow of the propellant gas across the throat zone 1.2 of the nozzle. The poles of the magnets 7.1 and 7.2 in order to give protection against the high propellant gas temperatures, are provided with a thin heat-insulating coating 11.

The electrodes 8 and 9 are separated from each other and from the magnets 7.1 and 7.2 by a material 12 which is an electrical insulator but nevertheless has good thermal conductivity.

WHAT WE CLAIM IS: 1. A rocket propulsion unit incorporating a magneto hydrodynamic electrical generator arranged to convert a part of the energy in the propellant gas stream to electrical energy the generator being arranged annularly around the throat of the combustion nozzle chamber.

2. A rocket propulsion unit according to claim 1, wherein the generator is arranged in the zone where maximum propellant gas flow speed occurs.

3. A rocket propulsion unit according to Claim 1 or 2, wherein the generator has at least one permanent magnet serving to produce a magnetic field.

4. A rocket propulsion unit according to any preceding claim, wherein cooling channels extend through the generator.

5. A rocket combustion chamber having an electrical generating means constructed and arranged to function substantially as herein described with reference to and as shown in the accompanying drawings.

**WARNING** end of DESC field may overlap start of CLMS **.

Claims (5)

**WARNING** start of CLMS field may overlap end of DESC **. electrodes 8 and 9 are subdivided into smaller -separate segments 8.1, 8.2, 8.3, 8.4 and 9.1, 9.2, 9.3, 9.4 to reduce Hall-effect losses. Cooling ducts 10 extend longitudinally through the generator 2 and are interconnected where the rocket propellants are used as coolantior open at each end if air flow due to motion is used as coolant. The arrangement of the cooling channels 10 and magnets 7.1 and 7.2 is shown more clearly in Figure 3. The permanent magnets 7.1 and 7.2 produce a magnetic flux perpendicular to the electrodes 8 and 9 and perpendicular to the direction of flow of the propellant gas across the throat zone 1.2 of the nozzle. The poles of the magnets 7.1 and 7.2 in order to give protection against the high propellant gas temperatures, are provided with a thin heat-insulating coating 11. The electrodes 8 and 9 are separated from each other and from the magnets 7.1 and 7.2 by a material 12 which is an electrical insulator but nevertheless has good thermal conductivity. WHAT WE CLAIM IS:

1. A rocket propulsion unit incorporating a magneto hydrodynamic electrical generator arranged to convert a part of the energy in the propellant gas stream to electrical energy the generator being arranged annularly around the throat of the combustion nozzle chamber.

2. A rocket propulsion unit according to claim 1, wherein the generator is arranged in the zone where maximum propellant gas flow speed occurs.

3. A rocket propulsion unit according to Claim 1 or 2, wherein the generator has at least one permanent magnet serving to produce a magnetic field.

4. A rocket propulsion unit according to any preceding claim, wherein cooling channels extend through the generator.

5. A rocket combustion chamber having an electrical generating means constructed and arranged to function substantially as herein described with reference to and as shown in the accompanying drawings.