A pulse jet thruster driven by a polyvinyl chloride electroactive gel material

Abstract

The application relates to a pulse jet propeller driven by a polyvinyl chloride electroactive gel material, belonging to the jet propulsion technical field; the propeller comprises a shell and a collapsible cabin arranged in the shell; one-way diaphragm pumps in communication with the collapsible cabin are arranged at the head / tail ends of the shell, water flows into the head end and is sprayed out of the tail end; clamping plate type driving modules are arranged on the two sides of the collapsible cabin; the collapsible cabin is compressed by applying a normal clamping force to the two side walls of the collapsible cabin, fluid in the cabin is extruded and sprayed out to complete a pulse jet propulsion action. The application realizes the water absorption and water spraying action of imitating a squid, and can complete flexible underwater movement and direction adjustment under low energy consumption.

Description

Technical Field

[0001] This invention belongs to the field of jet propulsion technology, specifically relating to a pulse jet propulsion device driven by polyvinyl chloride electroactive gel material. Background Technology

[0002] In the field of jet propulsion technology for underwater vehicles, researchers worldwide have developed two main types of biomimetic jet propulsion devices. The first type is a purely mechanical structure combined with power units such as motors to provide high speed and thrust, but it generates significant vibration and noise, and has poor biocompatibility and stealth capabilities. For example, the robotic fish developed by the University of California, San Diego, uses this design. The second type of propulsion device uses smart materials for actuation, offering advantages in maneuverability for specific applications, but it has limitations in propulsion efficiency and payload capacity.

[0003] With the rapid development of disciplines such as bionics, robotics, fluid mechanics, materials science, and automatic control theory, researchers have turned their attention to organisms that have long lived in water, hoping to gain inspiration for new underwater propulsion methods. In recent years, numerous biomimetic propulsion devices have been developed to improve underwater navigation performance and environmental adaptability. Summary of the Invention

[0004] The technical problem to be solved:

[0005] To avoid the shortcomings of existing technologies, this invention provides a pulse jet propulsion device driven by polyvinyl chloride electroactive gel material. By squeezing a retractable cabin through a clamp-type drive module and combining the rebound characteristics of the retractable cabin, it realizes a squid-like water intake and spraying action. It can complete low-noise, highly stealthy, and flexible underwater movement and directional adjustment with low energy consumption.

[0006] The technical solution of the present invention is: a pulse jet propulsion device driven by polyvinyl chloride electroactive gel material, comprising a shell and a retractable chamber disposed therein, wherein a one-way diaphragm pump communicating with the retractable chamber is provided at both the front and rear ends of the shell to control the water flow to enter from the front end and spray out from the rear end; a clamp-type drive module is provided on both sides of the retractable chamber, which compresses the fluid inside the chamber by applying a normal clamping force to the walls on both sides of the retractable chamber, thereby squeezing out the fluid inside the chamber to complete the pulse jet propulsion action.

[0007] A further technical solution of the present invention is: the retractable cabin has a planar structure on both sides symmetrical to the central symmetry plane of the thruster, and the cross section parallel to the central symmetry plane of the thruster is nearly elliptical; a one-way diaphragm pump mounting hole is opened at its head / tail end along the central axis; an elastic component is provided inside it along the direction perpendicular to the central symmetry plane, and the two ends of the elastic component are respectively connected to the inner wall of the planar structure on both sides to apply an elastic restoring force to the compressed wall surface.

[0008] A further technical solution of the present invention is that the material of the retractable cabin is silicone, and its cross-sectional profile parallel to the central symmetry plane of the thruster is NACA0020 line shape.

[0009] A further technical solution of the present invention is that the elastic component includes two compression springs arranged in parallel.

[0010] A further technical solution of the present invention is: the one-way diaphragm pump includes a DF-M65 diaphragm-type pressureless one-way valve installed at the front end of the thruster and a DF-X65V mini spring-type one-way valve installed at the rear end. When the retractable chamber draws in / drains fluid, a pressure difference is generated between the inlet / outlet of the one-way diaphragm pump at the front end and the one-way diaphragm pump at the rear end, so that the fluid enters the retractable chamber from the one-way diaphragm pump at the front end and exits the retractable chamber from the one-way diaphragm pump at the rear end.

[0011] A further technical solution of the present invention is: the clamp-type drive module includes two sets of drive components symmetrically arranged on both sides of the retractable chamber, and the drive components include a reversing linkage and a polyvinyl chloride electroactive gel material actuator hinged to both ends thereto.

[0012] The reversing linkage includes a bottom rod and two symmetrical connecting rods hinged to its central protrusion. The free ends of the two connecting rods are respectively hinged to the polyvinyl chloride electroactive gel material actuators at both ends. The bottom rod is connected to the side wall of the retractable chamber through a thin plate, and its axis is perpendicular to the side wall of the retractable chamber.

[0013] The PVC electroactive gel material actuator is composed of copper mesh and PVC gel material stacked alternately, with the stacking direction consistent with the propeller's travel direction. A 1Hz pulse voltage is applied for pulse power supply, causing it to expand and contract as a whole. The displacement generated by the expansion and contraction drives two connecting rods to rotate around the protrusion of the bottom rod, which in turn drives the thin plate to compress the retractable cabin along the normal direction through the bottom rod.

[0014] A further technical solution of the present invention is that the outline of the thin plate is consistent with the outline of the planar structure of the side wall of the retractable cabin, and it is a carbon fiber plate with a thickness of 0.75mm.

[0015] A further technical solution of the present invention is: the outer shell covers the outer surface of the clamp-type drive module and the retractable cabin, and is a linear rotating body structure transformed from the linear shape of NACA0020; the through hole for mounting the tail-end one-way diaphragm pump extends outward into a trumpet-shaped structure to increase the thrust generated by the jet; and a fin-like structure is provided on its outer periphery to increase the streamlined shape and stability of the propeller.

[0016] A further technical solution of the present invention is that the outer shell is 3D printed using polylactic acid (PLA) material.

[0017] A propulsion method for a pulse jet thruster driven by polyvinyl chloride electroactive gel material, comprising the following specific steps:

[0018] Adjust the pressure difference of the one-way diaphragm pump at the beginning and end of the housing;

[0019] Fluid is introduced into the retractable chamber via a one-way diaphragm pump at the bow, causing the retractable chamber to expand.

[0020] A 1Hz pulse voltage is applied to the PVC electroactive gel material actuator of the clamp-type drive module to provide pulse power, causing the PVC electroactive gel material actuator to expand and drive the reversing linkage located in the middle to move towards the retractable cabin.

[0021] The reversing linkages on both sides drive the thin plate to compress the retractable chamber. The fluid inside the retractable chamber is ejected from the outer shell by a one-way diaphragm pump at the tail end, and the thrust generated by the jet propels the thruster.

[0022] Beneficial effects

[0023] The beneficial effects of this invention are as follows: This invention uses a clamp-type drive module to squeeze the retractable chamber, squeezing the fluid inside the chamber out of the outer shell; and the elastic components inside the retractable chamber quickly restore it to its normal state, allowing it to enter the next round of jetting action.

[0024] Preferably, the clamp-type drive module is an actuator based on polyvinyl chloride (PVC) electroactive gel material. This material, with its excellent deformation capability, high stress output, and rapid response characteristics, makes efficient and lightweight underwater propulsion possible. The pulse jet thruster based on the PVC electroactive gel material actuator has the advantages of ultra-quiet operation and good biocompatibility. Compared with other new drive materials (such as dielectric elastomers which require a drive voltage of 2000V), it has a lower drive voltage, requiring only 200V. This thruster exhibits near-silent operation, with extremely low noise levels compared to mechanically driven similar products, demonstrating good biocompatibility and environmental friendliness. By flexibly adjusting the frequency of the output voltage, the thruster's propulsion frequency can be precisely controlled, thereby adjusting its speed to meet the speed requirements of different application scenarios.

[0025] This invention employs a one-way valve device to ensure unidirectional fluid flow—from the head to the tail of the thruster. This design significantly improves propulsion efficiency and enhances system reliability.

[0026] This invention's propulsion system helps submarines perform missions without being detected by enemy sonar, gaining a tactical advantage. In marine biological observation, the propulsion system has good biocompatibility, allowing it to blend seamlessly into schools of fish and obtain accurate observational data. In underwater archaeology, the propulsion system reduces environmental interference, playing a crucial role in protecting underwater artifacts. With further technological development and refinement, this propulsion system is expected to play an even more important role in future underwater operations. Attached Figure Description

[0027] Figure 1 This is a schematic diagram of the pulse jet propulsion device driven by polyvinyl chloride electroactive gel material according to the present invention;

[0028] Figure 2 This is a schematic diagram of a unidirectional diaphragm pump.

[0029] Figure 3 This is a schematic diagram of the silicone retractable chamber.

[0030] Figure 4 This is a schematic diagram of the actuator part of the polyvinyl chloride electroactive gel material;

[0031] Figure 5 This is a schematic diagram of the reversing linkage.

[0032] Figure 6 This is a schematic diagram of the thin plate structure;

[0033] Figure 7 This is a schematic diagram of the structure supporting the outer shell.

[0034] Explanation of reference numerals in the attached drawings: 1-One-way diaphragm pump, 101-One-way valve inlet, 102-One-way valve, 103-One-way valve outlet, 2-Retractable chamber, 201-Compression spring, 202-Profile one-way diaphragm pump mounting hole, 203-Tail one-way diaphragm pump mounting hole, 3-Polyvinyl chloride electroactive gel material actuator, 301-Lumber, 4-Reversing linkage, 401-Linkage, 402-Bottom rod, 5-Sheet, 501-Bottom rod mounting hole, 6-Outer shell, 601-Round hole, 602-Fin structure, 603-Trumpet structure. Detailed Implementation

[0035] The embodiments described below with reference to the accompanying drawings are exemplary and intended to explain the invention, and should not be construed as limiting the invention.

[0036] In the description of this invention, it should be understood that the terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," and "counterclockwise," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0037] Addressing the issues of high noise and poor concealment in existing biomimetic propulsion devices, this invention provides a pulse jet propulsion device driven by polyvinyl chloride electroactive gel material. The device includes a housing and a retractable chamber housed within it. A one-way diaphragm pump, connected to the retractable chamber, is installed at both the front and rear ends of the housing, controlling water flow to enter from the front end and exit from the rear end. Clamp-type drive modules are located on both sides of the retractable chamber. By applying a normal clamping force to the side walls of the retractable chamber, the fluid inside is compressed and ejected to complete the pulse jet propulsion action.

[0038] Specifically, the retractable cabin has a planar structure on both sides symmetrical to the central plane of the thruster, and the cross section parallel to the central plane of symmetry of the thruster is nearly elliptical; one-way diaphragm pump mounting holes are opened at its head / tail end along the central axis; an elastic component is provided inside it along the direction perpendicular to the central plane of symmetry, and the two ends of the elastic component are respectively connected to the inner walls of the two planar structures, applying an elastic restoring force to the compressed wall surface.

[0039] Specifically, the clamp-type drive module includes two sets of drive components symmetrically arranged on both sides of the retractable cabin. Each drive component includes a reversing linkage and polyvinyl chloride electroactive gel material actuators hinged at both ends. The reversing linkage includes a base rod and two symmetrical connecting rods hinged to its central protrusion. The free ends of the two connecting rods are respectively hinged to the polyvinyl chloride electroactive gel material actuators at both ends. The base rod is connected to the side wall of the retractable cabin through a thin plate, and its axis is perpendicular to the side wall of the retractable cabin. The polyvinyl chloride electroactive gel material actuator is composed of copper mesh and polyvinyl chloride gel material stacked alternately, with the stacking direction consistent with the propeller's travel direction. A 1Hz pulse voltage is applied for pulse power supply, causing it to expand and contract as a whole. The displacement generated by the expansion and contraction drives the two connecting rods to rotate around the protrusion of the base rod, thereby driving the thin plate to compress the retractable cabin along the normal direction through the base rod.

[0040] The present invention discloses a propulsion method for a pulse jet propulsion device driven by polyvinyl chloride electroactive gel material, the specific steps of which are as follows:

[0041] Step 1: Adjust the pressure difference of the one-way diaphragm pump at the beginning and end of the housing;

[0042] Step 2: Fluid is introduced into the retractable chamber through a one-way diaphragm pump at the bow, causing the retractable chamber to expand;

[0043] Step 3: Apply a 1Hz pulse voltage to the PVC electroactive gel material actuator of the clamp-type drive module to provide pulse power, causing the PVC electroactive gel material actuator to expand and drive the reversing linkage located in the middle to move towards the retractable chamber.

[0044] Step 4: The reversing linkages on both sides drive the thin plate to compress the retractable chamber. The fluid inside the retractable chamber is ejected from the outer shell by the one-way diaphragm pump at the tail end. The thrust generated by the jet propels the thruster.

[0045] The above technical solution will be further explained below with reference to the accompanying drawings:

[0046] In one embodiment, refer to Figure 1 As shown, a pulse jet propulsion device driven by a polyvinyl chloride electroactive gel material includes:

[0047] One-way diaphragm pump section 1 is located at the head and tail of the propulsion device and is used to restrict the one-way flow of fluid inside the propulsion device.

[0048] Preferably, the one-way diaphragm pump 1 consists of two one-way valves: a DF-M65 diaphragm-type pressureless one-way valve at the head and a DF-X65V mini spring-type one-way valve at the tail. The one-way diaphragm pumps at both the head and tail ends have a pressure difference, which makes it easier for fluid to enter the 101 chamber, which is in line with the driving characteristics of the polyvinyl chloride electroactive gel material actuator.

[0049] Preferred, refer to Figure 2 As shown, the one-way diaphragm pump 1 includes a one-way valve inlet 101 and a one-way valve outlet 103, as well as a one-way valve connected between the inlet and the outlet.

[0050] The retractable cabin 2 is used to carry the fluid inside the propulsion device;

[0051] Preferably, the retractable chamber 2 is made of BESHOW SKIN 10 professional-grade silicone, which possesses high physical properties and is the best silicone for creating human and animal skin. Its unique high tensile strength and high resilience make it suitable for creating various mechanically demanding stretching actions. The chamber is internally supported by two short springs to ensure timely rebound. The overall chamber design utilizes a modified NACA0020 linear profile. (Refer to...) Figure 3As shown, its structure is flat on the left and right sides and convex at the top and bottom, facilitating compression of the device. The compression capacity of this shape is 30% higher than that of a rectangular structure of the same volume under the same stress. Both the head and tail of the chamber have circular holes, allowing for a smooth transition between the silicone retractable chamber and the one-way diaphragm valve. Two rigid thin plates are installed on both sides of the silicone retractable chamber.

[0052] Part 3 of the PVC electroactive gel material driver section, refer to Figure 4 As shown, the four corners on both sides of the silicone retractable chamber are used to provide driving force;

[0053] Preferably, the polyvinyl chloride electroactive gel material actuator is formed by stacking polyvinyl chloride gel material and copper mesh. Polyvinyl chloride (PVC) gel material is an electroactive smart material that can deform under the action of an applied electric field. The theoretical basis of this material is the electrodeformation effect of electroactive polymers, that is, under the action of an electric field, the molecules inside the polymer will rearrange and recombine, thereby causing the material to deform. The polyvinyl chloride electroactive gel material actuator is composed of copper mesh and polyvinyl chloride material stacked alternately, and the stacking method is arranged along the direction of propeller movement. This arrangement can reduce the drag encountered by the device when navigating in water.

[0054] Reversing link 4, refer to Figure 5 As shown, it includes a base rod 402 and two symmetrical connecting rods 401 hinged to its central protrusion. The free ends of the two connecting rods 401 are respectively hinged to the lugs 301 at the inner ends of the polyvinyl chloride electroactive gel material actuators at both ends; used to convert the lateral force generated by the polyvinyl chloride electroactive gel material actuator 3 into a longitudinal force, that is, to retract the normal direction of the two side walls of the cabin 2.

[0055] Thin plate 5 is used to increase the force-bearing area of ​​the compressible silicone cavity; see reference. Figure 6 As shown, a through hole is opened at its center for installing the bottom protrusion of the base rod 402.

[0056] The supporting outer shell 6 is used to fix the polyvinyl chloride electroactive gel material actuator, reversing linkage, thin plate and silicone retractable cabin. There are round holes 601 at the head and tail. The supporting outer shell can cooperate with the one-way diaphragm valve. The fin structure 602 is symmetrically arranged below the cabin to maintain the stability of the vehicle. This sealed structure can waterproof the internal structure.

[0057] In a preferred embodiment, the polyvinyl chloride electroactive gel material actuator 3 is symmetrically supported and segmented within the outer shell on both sides of the thruster, and the lug 301 at its inner end is hinged to the free end of the connecting rod 401 of the reversing link 4; the outer surface of the polyvinyl chloride electroactive gel material actuator 3 is fitted with the supporting outer shell 6 to achieve a precise combination of the various parts.

[0058] In a preferred embodiment, the unidirectional diaphragm pump 1 is in the same direction, and the direction of the fluid flow inside is controlled as head-body-tail.

[0059] In a preferred embodiment, the supporting outer shell 6 is a linear rotating body structure converted from NACA0020. Compared with a cuboid of the same mass and volume, the resistance of the fluid linear structure is reduced by 50%. It is precisely wrapped with the polyvinyl chloride electroactive gel material actuator 3 and the silicone shrinkable chamber 5 of the internal device, so that the silicone shrinkable chamber is in a normal state when not powered on.

[0060] In a preferred embodiment, the thin plate 5 has a thickness of 0.75 mm and its shape is identical to the planar structure of the two sides of the silicone retractable chamber. The selected material is carbon fiber plate, which has the advantages of high strength and high modulus.

[0061] In a preferred embodiment, the thin plate 5 has a square hole 501 in the middle to cooperate with the bottom rod 402 of the reversing linkage.

[0062] In a further preferred embodiment, the reversing linkage 4 is connected to the polyvinyl chloride electroactive gel material actuator 3 via a metal linkage 401, and the lower bottom rod 402 is connected to the thin plate 501. When the polyvinyl chloride actuator performs reciprocating motion, the linkage motion will change the motion direction to the normal direction of the thin plate in order to compress the silicone shrinkable chamber 2.

[0063] In a preferred embodiment, the polyvinyl chloride electroactive gel material driver 3 is formed by continuously stacking a thin copper mesh and a polyvinyl chloride layer.

[0064] In a preferred embodiment, the polyvinyl chloride electroactive gel material actuator 3 is powered by a 1Hz pulse voltage to cause it to expand and contract as a whole, thereby indirectly providing compression displacement for the compressible cavity.

[0065] In a preferred embodiment, the supporting outer shell 6 is 3D printed using polylactic acid (PLA) material.

[0066] Further preferably, the tail of the supporting outer shell 6 is designed as a trumpet-shaped structure 603, which can increase the thrust generated by the jet; fin-shaped structures 602 are designed on the upper and lower sides to increase the streamlined shape and stability of the device.

[0067] Further preferably, the silicone shrinkable chamber 2 is cast from BESHOW SKIN 10 professional special-effect silicone. First, a model is 3D printed, and then the corresponding shape is cast using silicone. It is then bonded together with an adhesive, and internal silicone-bonded springs 201 support the silicone chamber.

[0068] Further preferably, the silicone shrinkable chamber 2 has a silicone casting thickness of 2mm, which gives the silicone chamber a certain degree of elasticity and toughness.

[0069] The compressible capsule of this invention is designed with a streamlined shape to effectively reduce drag and drive energy consumption during navigation. This design employs a novel voltage-driven drive, effectively increasing energy efficiency. A 1Hz pulsed voltage is used for power supply, and the drive unit is arranged in an axisymmetric distribution to maintain good stability during propulsion.

[0070] Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of the present invention without departing from the principles and spirit of the present invention.

Claims

1. A pulse jet propulsion device driven by polyvinyl chloride electroactive gel material, characterized in that: The device includes a shell and a retractable chamber disposed therein. The shell is equipped with a one-way diaphragm pump at both its front and rear ends, which communicates with the retractable chamber to control the water flow to enter from the front end and spray out from the rear end. The retractable chamber is provided with a clamp-type drive module on both sides. By applying a normal clamping force to the walls of the retractable chamber, the fluid inside the chamber is compressed and squeezed out to complete the pulse jet propulsion action. The retractable cabin has a planar structure on both sides symmetrical to the center plane of the thruster, and the cross section parallel to the center plane of symmetry of the thruster is nearly elliptical; one-way diaphragm pump mounting holes are opened at its front / rear ends along the central axis; elastic components are provided inside along the direction perpendicular to the center plane of symmetry, and the two ends of the elastic components are respectively connected to the inner walls of the planar structures on both sides to apply elastic restoring force to the compressed wall surface. The clamp-type drive module includes two sets of drive components symmetrically arranged on both sides of the retractable cabin. The drive components include a reversing linkage and a polyvinyl chloride electroactive gel material actuator hinged to both ends of the linkage. The reversing linkage includes a bottom rod and two symmetrical connecting rods hinged to its central protrusion. The free ends of the two connecting rods are respectively hinged to the polyvinyl chloride electroactive gel material actuators at both ends. The bottom rod is connected to the side wall of the retractable chamber through a thin plate, and its axis is perpendicular to the side wall of the retractable chamber. The PVC electroactive gel material actuator is composed of copper mesh and PVC gel material stacked alternately, with the stacking direction consistent with the propeller's travel direction. A 1Hz pulse voltage is applied for pulse power supply, causing it to expand and contract as a whole. The displacement generated by the expansion and contraction drives two connecting rods to rotate around the protrusion of the bottom rod, which in turn drives the thin plate to compress the retractable cabin along the normal direction through the bottom rod.

2. The pulse jet propulsion device driven by polyvinyl chloride electroactive gel material according to claim 1, characterized in that: The retractable cabin is made of silicone, and its cross-sectional profile, parallel to the central symmetry plane of the thruster, is NACA0020.

3. The pulse jet propulsion device driven by polyvinyl chloride electroactive gel material according to claim 1, characterized in that: The elastic component includes two compression springs arranged side by side.

4. The pulse jet propulsion device driven by polyvinyl chloride electroactive gel material according to claim 1, characterized in that: The one-way diaphragm pump includes a DF-M65 diaphragm-type pressureless one-way valve installed at the front end of the thruster and a DF-X65V mini spring-type one-way valve installed at the rear end. When the retractable chamber draws in / drains fluid, a pressure difference is generated between the inlet / outlet of the front-end one-way diaphragm pump and the tail-end one-way diaphragm pump, so that fluid enters the retractable chamber from the front-end one-way diaphragm pump and exits the retractable chamber from the tail-end one-way diaphragm pump.

5. The pulse jet propulsion device driven by polyvinyl chloride electroactive gel material according to claim 1, characterized in that: The profile of the thin plate is consistent with the profile of the planar structure of the side wall of the retractable cabin, and it is a carbon fiber plate with a thickness of 0.75mm.

6. The pulse jet propulsion device driven by polyvinyl chloride electroactive gel material according to claim 1, characterized in that: The shell covers the outer surface of the clamp-type drive module and the retractable cabin, and is a linear rotating body structure transformed from the NACA0020 linear shape; the through hole for mounting the tail-end one-way diaphragm pump extends outward into a trumpet-shaped structure to increase the thrust generated by the jet; its outer periphery is provided with a fin-like structure to increase the streamlined shape and stability of the propeller.

7. The pulse jet propulsion device driven by polyvinyl chloride electroactive gel material according to claim 6, characterized in that: The shell is 3D printed using polylactic acid (PLA) material.

8. A propulsion method for a pulse jet propulsion device driven by a polyvinyl chloride electroactive gel material as described in any one of claims 1-7, characterized in that... The specific steps are as follows: Adjust the pressure difference of the one-way diaphragm pump at the beginning and end of the housing; Fluid is introduced into the retractable chamber via a one-way diaphragm pump at the bow, causing the retractable chamber to expand. A 1Hz pulse voltage is applied to the PVC electroactive gel material actuator of the clamp-type drive module to provide pulse power, causing the PVC electroactive gel material actuator to expand and drive the reversing linkage located in the middle to move towards the retractable cabin. The reversing linkages on both sides drive the thin plate to compress the retractable chamber. The fluid inside the retractable chamber is ejected from the shell by a one-way diaphragm pump at the tail end, and the thrust generated by the jet propels the thruster.

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