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[[Category:Pumps]]
[[Category:Pumps]]
CHAPTER 1
INTRODUCTION
A Pistonless pump is a type of pump designed to move fluids without any moving parts other than three chamber valves .A positive displacement pistonless rocket fuel pump uses two pumping chambers alternately filled and pressurized in sequence to maintain a steady flow of pressurized propellant to a rocket engine. NASA has developed a low cost rocket fuel pump which has comparable performance to turbo pump at 80-90% lower cost. Perhaps the most difficult barrier to entry in the liquid rocket business is the turbo pump. The function of the rocket engine turbo pump is to receive the liquid propellants from the vehicle tanks at low pressure and supply them to the combustion chamber at the required flow rate and injection pressure. A turbo pump design requires a large engineering effort and is expensive to manufacturing and test. Starting a turbo pump fed rocket engine is a complex process, requiring a careful of many valves and subsystems. In fact Beal aerospace tried to avoid the issue entirely by building a huge pressure feed booster. Their booster never flew, but the engineering behind it was sound and if they had a low cost pump at their disposal, they might be competing against Boeing. This pump saves up to 90% of the mass of the tanks as compared to a pressure fed system. This pump has really proved to be a boon for rockets. By this pump the rocket does not have to carry heavy load and can travel with very high speed.
A heavy lift rocket with man rating capability is necessary for human exploration of the solar system. The key is to develop a vehicle quickly, before the design process gets politicized. The tall pole in the launch vehicle development is the turbo pump, which is the single most expensive and time consuming part of the vehicle. A vehicle with 5 engines of 2 million lbs thrust is one possible scenario. Developing a new 2 Mlbf turbopump will take too long. Building a vehicle with strap on solids will be too risky, and using many of off the shelf engines drives up costs. An upgraded F-1a thrust chamber with a pistonless pump gets around this problem with a quick and straightforward design, test and integration process.


CHAPTER 2
NECESSITY
Turbo pumps are currently used in the majority of launch vehicles, although piston pumps have been designed and flown and pneumatic diaphragm pumps have been proposed by Godwin and Sobey. The turbo pump containing many rotating parts, which leads to frictional loss. Turbo pump pressurization system is considerably more complex than gas pressurization system. Design of pump is the greatest problem that will handle the liquid safely and without leaks. So, there must be a device which overcomes all the drawbacks of the turbo pump. The pistonless pump is the solution for the problems faced by using turbo pumps. They have only a drawback that they supply fuel with less pressure as compared to turbo pumps.
The pistonless pump considered herein is much simpler and less expensive than a turbopump. The pump concept is simple: instead of having the whole fuel tank pressurized to 2-7 MPa, the main tank is at pressurized to 100-400 kPa and it is drained into a pump chamber, and then the pump chamber is pressurized to deliver fuel to the engine. An auxiliary chamber supplies fuel while the main pump chamber is being refilled. This type of pump has benign failure modes, can be installed in the fuel tank to minimize vehicle size and uses inexpensive materials and processes in its construction. With the right choice of materials, the pump will be compatible with all common rocket fuels. The pump can be started instantly, with no spool up time required. It can be run until the tank is dry with no concerns about cavitation or over speeding. The simplicity and low cost of the pump allows for systems with engine out capability or allows for the use of tri-propellant systems. This pump lends itself to mass production techniques for low cost systems with multiple engines and tanks. The pump can be easily scaled up or down with no loss of performance. The pump can be stored for a long time with no degradation.




CHAPTER 3
DUAL PISTONLESS PUMP
A positive displacement pistonless pump is a type of pump designed to move fluids without any moving parts other than three chamber valves. The pump contains a chamber which has a valved inlet from the fluid to be pumped, a valved outlet both of these at the bottom of the pump, and a pressurant inlet at the top of the pump. A pressurant is used, such as steam or pressurized helium, to drive the fluid through the pump.

Figure 1: Basic Pump design

3.1 WORKING OF THE PUMP

In pistonless pump two pumping chambers are used, each one being alternately refilled and pressurized. The pump is powered by pressurized gas which acts directly on the fluid. The pump is designed so that the time required to vent, refill and pressurize one pumping chamber is less than the time to dispense a given quantity of fuel from the other. The pump controls are set up so that when the level in one side gets low, the other side is pressurized; and then after flow is established from both sides, the low side is vented and refilled. This results in steady flow and pressure. A model of this pump was designed and built out of clear plastic, and it performed as expected delivering steady flow and pressure. The pressures and flow rates were measured and the data was analyzed to determine how to improve the pump performance.
The pistonless pump is similar to a pressure fed system, but instead of having the a main tank at high pressure (typically 300-500 psi) the proposed pump system has a low pressure tank (5 -50 psi) which delivers propellant at low pressure into a pump chamber, where it is then pressurized to high pressure and delivered to the engine. A diagram of the pump operation is shown in Figure 1. Two pumping chambers are used in each pump, each one being alternately refilled and pressurized.
The pump starts with both chambers filled (Step 0, not shown). One chamber is pressurized, and fluid is delivered to the rocket engine from that chamber (Step 1). Once the level gets low in one chamber, (Step 1a) the other chamber is pressurized; and flow is thereby established from both sides during a short transient period (Step 2) until full flow is established from the other chamber. Then the nearly empty chamber is vented and refilled. (Step 3) Finally the cycle repeats. This results in steady flow and pressure.
The pump is powered by pressurized gas which acts directly on the fluid. Initial tests showed pressure spikes as the pump transitioned from one chamber to the other, but these have since been eliminated by adjusting the valve timing. This pump is more robust than a piston pump in that it has no high pressure sliding seals, and it is much less expensive and time consuming to design than a turbopump and a system which uses the pump has far lower dry mass and unusable residuals than turbopumps do.



























Figure 2: Dual pistonless pump working cycle

3.2 PUMP DESIGN CONSIDERATIONS
Although the pump design is simple, the optimization process is not. Making the pump cycle as fast as possible would make it lightweight, but higher flow velocities cause problems. A pump with a small chamber must be filled and vented quickly, with minimal head loss through the gas and liquid valves and plumbing. The maximum inflow rate is limited by the main tank pressure (usually about 300 kPa) and the area of the inlet valves. Also, if the inflow velocity is too high, the propellant will be aerated, which may cause problems with the engine. The ullage volume in the pump chamber should be small to minimize gas usage, but if it is too small, there will be a loss of propellant through the vent. Furthermore, the pump cycle frequency must not excite any combustion instabilities in the rocket motor. The second generation pump design process started with the realization that by placing the pump chamber inside the main tank and increasing the size of the check valves, the pump can be filled very quickly. Once the pump is being filled much faster than it is emptied, it becomes clear that the two chambers do not have to be symmetrical.
Figure 3: Prototype optimized pump design

Instead of two similar pump chambers, it uses one main chamber which supplies fuel for most of the time and an auxiliary chamber which supplies fuel for the rest of the time. The main chamber is placed inside the tank, and it is filled through a number of check valves so that it can be filled quickly, thereby reducing the size of the auxiliary chamber, which is typically one fourth the size of the main chamber. The optimized design offers a substantial weight savings over the basic design, in that it uses one primary pumping chamber and one auxiliary chamber instead of two pumping chambers. A prototype of this type of pump is shown in Figure 4. The tank is made of stainless steel, the valves are brass, and the seals are Teflon so that it can be used to pump LOX.

Figure 4: Photo of pump assembly with flange for attachment to tank.
The prototype includes a flange to easily attach it to the bottom of a tank. The prototype uses cylindrical tanks instead of spherical for ease of manufacture. It weighs approximately 6.8 kg exclusive of the air valves and the bottom flange.

CHAPTER 4
PUMP DESIGN PROCESS
4.1 CHAMBER PRESSURE
The first step in the development process is to determine the best combustion chamber pressure. For a pistonless pump system, the pump weight is proportional to the pressure, but the pump weight does not drive the system design. Instead, the weight of the pressurant which drives the pump is the key factor, just as it is for a gas generator turbopump system. For a turbopump operating with a chamber pressure of 1000 Pisa and LOX HC propellants, the gas generator burns about 2.5% of the of the propellant in the gas generator. At higher pressures, proportionally more propellant is burned, and although the ISP increases with pressure, the optimum chamber pressure is on the order of 1000 psi.
4.2 PUMP CHAMBER DESIGN
The pump chambers will need to be cylinders with a float to separate the liquid and gas phases and reduce the collapse of the pressurant gas due to cooling. The pressurant gas temperature may be low, so the pump chambers can be aluminum, stainless or carbon fiber reinforced plastic. The mass of the pump chambers is easily determined based on the pressure and volume requirements. A conservative pump chamber cycle time is 5 seconds. This allows the dynamic pressure in the pump chamber to be quite low, so that the propellant can be managed under low acceleration. After coast periods, the propellant in the pump chamber may develop a bubble of vapor under the float. The float must allow this propellant vapor to escape the pump chamber while keeping the liquid below the float. A PMD in the bottom of the pump chamber can prevent bubble from reaching the thrust chamber as long as the system starts up slowly. Once the pump and the thrust chamber are providing acceleration to the vehicle, the vapor can escape along the sides of the float through a helical passage that is configured as a dynamic check valve. The dynamic check valve pumps vapor above the float as the pump cycles. The float must be insulated to prevent excess collapse of the pressurant gas due to contact with the pump chamber walls and the propellant surfaces. An insulated float design is shown in Figure 5. This design prevents heat transfer to the pumped propellant and the propellant in the tank. The top of the pump chamber and the pressurization and vent lines are also insulated. The open top float allows the float to be light enough to float on top of liquid hydrogen.
Figure 5: Pump with insulated float system
The open top, self-bailing float was chosen to act as a physical barrier between the relatively warm gas phase pressurant and the cryogenic liquid. This float was developed using a semi-empirical process discussed below. To allow a loose fit within the pump chamber, yet act as a barrier between the two phases, features were added to the float cylindrical walls. These features called “Tesla grooves” are derived from fluidic Tesla check valves. A drawing from Tesla’s patent 1329559 is shown in Figure 6. They allow the flow resistance to be greater in one direction. This allows some of the pressurant gas to act directly on the fluid surface, but minimizes any “blow-by” of the cryogenic liquid, which could be vented out of the pump. A float with a helical Tesla groove was selected, based on testing in a transparent, acrylic pump model where carbonated water was pumped to simulate pumping cryogenic fluid near saturation.
Figure 6: Tesla’s Valve, Free Flow is From Right to Left.
The helical Tesla groove concept (with a small vent hole at the top of the helical grove) allowed any bubbles trapped under the float to vent out from under the float more efficiently during the venting portion of the cycle. To minimize gas usage, the ullage space in each cavity must be a minimum. To accomplish this, a filler block was designed which would mount to the top of each chamber and allow the float to nestle over it when the float reaches top-dead-center (see Figure 7). The filler block was tested in a bucket of liquid nitrogen, and it worked to prevent the float from sinking, even when the block and the float were both completely submerged. This was due to the float sealing against the filler block so that as it was pulled up, very little LN2 could flow in between the float and the filler block. This showed that during the dispense cycle, as the float separates from the filler block; the float was left floating in the LN2 with a small amount of LN2 in the float. In the pump system, even if the float fills with LN2, it will be bailed out during the first vent cycle.The float shown in figure 7 includes a ring which contains magnets for level sensing.
Figure 7: Model of Float with Helical Tesla Valve
Figure 8: Float in top-dead-center (TDC) and bottom-dead-center (BDC) positions
4.3 CYCLE TIME
The pump cycle time (Tcycle) should be as fast as possible to minimize the volume and thereby the mass of the pump chamber. However, the cycle time is limited by the response time of the valves and the time required to vent, fill and the pressurize pump chambers. The time required to dispense from the chamber should be longer than the other times, so that the main chamber can vent, refill and pressurize during the time that the auxiliary chamber is dispensing. The vent time is the time required for the pump chamber pressure to fall below the tank pressure so that the chamber can begin filling. Assuming that we are starting with a nearly empty pump chamber which is still full of pressurant gas, the first step is to open the vent valve, which takes about 30 ms. Then the pressurant gas flows through the valve under choked and then subsonic conditions.
4.4 PLUMBING DESIGN
The duct sizes can be quickly determined by the requirement that the dynamic pressure be much less than the static pressure, a few percent at most. Placing the pump chamber inside the tank can solve the issue of water hammer; fill duct sizing and thermal conditioning. This will require high pressure plumbing to the engine, but this problem has been solved for various pressure fed systems.
4.5 VALVES AND REGULATORS
For the check valves, they operate slowly, with predictable changes in pressure, so the valves may be selected based on weight and reliability, and chatter is easily avoided. The outlet check valves need to be sized for low-pressure drop at the outlet flow rate, perhaps 2 to 4 psi. (Less than 1% of the output pressure) .The inlet valves need to be sized for about twice the flow rate of the outlet valves, so that the pump chambers can fill more quickly than they dispense. The pressure drop for the inlet check valves is based on the tank pressure and the desired inlet dynamic pressure. A check valve which is too small and has a high operating deltaP may require an elaborate diffuser to allow the pump chamber to fill without entraining residual pressurant gas, so the best solution is to use valves of excess capacity on the inlet check valves. If the pump is placed inside the tank, the valve seat can be built into the pump chamber wall, so the weight penalty for a large valve is low.
4.6 TANK PRESSURIZATION SYSTEM
Autogenous Pressurization concept is based on heating the propellants at the engine and using the heated propellants to run the pump, similar to an expander cycle turbopump design. A typical system design is shown in Figure 9. This system is designed for a 10 minute burn at 36,000 lbf with a propellant pressure of 350 psi and a pressurant temperature of 540 R (similar to RL-10). The smaller pressurant pumps act as gas generators converting liquid propellant (LOX or LH2) to gas (GOX or GH2). The pressurant pumps run on helium gas which is then vented into the main propellant tanks to provide pressurization. The pressurant pump vent gas is not enough to pressurize the tanks completely, so they require additional helium pressurant as well. The liquid output from the pressurization pumps is connected to a nozzle-mounted heat exchanger where it is vaporized to a gas and then used as the pressurant for the main pumps.








Figure 9: Autogenous pressurization system
4.7 CONTROL SYSTEM
The control system uses information about the chamber levels, pressures and flow rate to determine when to actuate the pressurize and vent valves. Using more sensors than absolutely necessary allows the system to implement integrated vehicle health monitoring. For example the pump would normally actuate the valves based on the level in the chambers, but if propellant volume rate of change based the level sensors did not agree with the turbine meter output, the system could verify the flow rate based on the thrust chamber pressure and determine which sensors to ignore.
4.8 HEAT TRANSFER
The heat transfer from the heated pressurant to the propellant should be limited in order to maintain consistent propellant density at the thrust chamber. The heat transfer to the propellant can be minimized by diffusing the pressurant gas as it enters the pump chamber in order to reduce the velocity and turbulence at the liquid to gas interface. In addition, during the initial pressurization process, the gas which is initially in the chamber will be heated by adiabatic compression. If the propellant is close to its boiling point, it may be subject to heating by adiabatic compression as well. At the end of the pump cycle, the chamber will be subject to adiabatic expansion of a larger sample of pressurant gas, so the net effect will in general be one of cooling. The exact amount of cooling or heating can be calculated based on computational fluid dynamics.
4.9 PUMP DESIGN SUMMARY
The pump chamber volume can be sized based on a cycle time of 3 seconds. The auxiliary chamber should be about 2/3 the volume of the main chamber. The wall thickness of the pump chamber can be determined based on the pressure and required safety factor. Composites, aluminum, stainless steel or titanium can be used depending on propellant compatibility and heat resistance. For the current case of a 2 MLbF (MN) LOX kerosene system, the LOX flow rate is 30,000 gpm (2 m3/sec) so the main LOX chamber diameter is 8 ft (2.2m) with a volume of 1500 gallons (5.7 m3). A 16 inch duct can flow the required amount of LOX with a dynamic pressure of 5 psi.

CHAPTER 5
INTEGRATION INTO ROCKET VEHICLE
To use the pump into a vehicle, a pump would be placed in both the oxidizer and fuel tanks and a third pump or a set of pumps would be used to supply pressurant to a gas generator. The pressurant pump(s) would run on pressurized Helium or air. The pump(s) would either supply propellant to a gas generator or liquefied gas to an engine-mounted heat exchanger. Heavy pressurant tanks would not be required. Because the pump weight scales linearly with flow rate and pressure there is no penalty associated with size. Therefore the rocket vehicle can use a number of independent tanks, engines and pumps to insure redundancy.
For example, there could be 6 or more propulsion modules arranged in a ring, if one system failed, the one on the opposite side could be shut down, the remaining engines could be throttled up and the vehicle could continue. Also, because the pump chamber is relatively small, the fuel pressure can be easily controlled to vary the thrust. Analysis of the system and mission will determine the optimum chamber pressure for the vehicle.

Figure 10: Pistonless Pumped Stage

CHAPTER 6
MODEL DESIGN AND TEST RESULTS
A model has been designed that performs as expected pumping water at 1.2 kg/s and 3 MPa. A conservative cycle time of 6 seconds was used for these preliminary tests. The main chamber supplies fluid for 5 seconds and the auxiliary chamber supplies fluid for 1.5 seconds, allowing approximately 250 ms of overlap during each valve switchover. The model is constructed of off-the-shelf industrial and consumer valves, level sensors and fittings.
The sequencing is controlled by the same computer that acquires data on the pump operation. Note that there are 20 msec wide pressure spikes as the second chamber is pressurized. The minor pressure spikes at switchover may be due to the mass of fluid in one pumping chambers slowing down as the other pumping chamber starts to flow during the overlap time when both chambers are pressurized.
Figure 11: Prototype pump output.

6.1 TESTING WITH LIQUID NITROGEN
The pump has been tested with liquid nitrogen and it works well. Figure shows the test in progress, the pump is inside the tank.





Figure 12: Liquid nitrogen test.
When pumping liquids near the boiling point, the liquid must be prevented from boiling excessively during the vent cycle. This may be achieved by venting through a back pressure regulator or by shutting the vent when the pump chamber pressure falls below a preset level. This is particularly important when the pump is used at altitude or in space.
6.2 TESTING WITH ATLAS VERNIER ENGINE
The pump has been tested with an Atlas vernier engine as a proof of concept test. The pump worked well maintaining pressure even as the engine suffered an o-ring failure which caused excessive fuel flow. The pump delivered kerosene at 2.8 Mpa and 1.1 kg/s. The LOX was pressure fed for this test. Figure 13 shows the engine running with kerosene supplied by the pump.




Figure 13: Atlas vernier engine running with fuel pumped and pressure fed
CHAPTER 7
ZERO-GEE PUMP SYSTEM
A model of the pump was designed, built and tested to show how the pump works under zero gravity. For successful zero gravity operation, the pump must be filled and emptied of propellant without dispensing any bubbles. Initial testing was done with water in a small pump chamber as a secondary experiment run at the Microgravity University at JSC. The pump test system used an onboard air compressor, tank and regulator to supply air to a pressurized ‘propellant’ tank and the pump chamber (Figure 14). The pump chamber included electrodes to measure the fluid level. The water had 5% vinegar added to it to make it electrically conductive without leaving any residue. A Netburner embedded computer controlled the pump operation.
Figure 14: Microgravity Pump test
The experiment involved observing the behavior of water in a clear acrylic chamber as it cycled though pumping and venting stages. The inlet to the pump chamber goes through a metal foam disc (Figure 15).The metal foam reduces the dynamic pressure of the incoming liquid and increases the surface tension pressure due to the small pores in the metal foam so that it will not create a bubble in the pump chamber as it is filled or emptied .A small high definition video camera recorded the process to investigate the effect of microgravity on the fluid being pumped .A low pressure(~5psi) PVC reservoir filled with water was used to fill a smaller pump chamber. The air in the pump chamber was vented into a collection system in the event that any liquid escaped out the vent .The pump chamber was then pressurized (~10psi). Through a cycle of pressurization and venting, the output water was fed directly back into the supply reservoir which used a bladder to maintain an all liquid feed to the pump chamber. The filling process showed a flat meniscus until the fluid approached the electrode for the conductivity based level sensor, at which point the fluid appeared to be attracted to the sensor electrode.
Figure 15: Pump Chamber with PMD
During the dispense process the meniscus was depressed in the center. The experiment worked perfectly, the surface tension of the fluid to the walls of the 1-inch diameter acrylic tube pump chamber was enough to maintain a meniscus that kept the air and water separate. For a system which uses cryogenic fluids in contact with vapor , the surface tension will be much less, but this first experiment show that propellant management is feasible under the moderate dynamic pressures typical for this pump.





CHAPTER 8
SPACECRAFT APPLICATIONS OF THE PUMP
This pump offers substantial performance and flexibility improvements for a space vehicle such as the Crew Exploration Vehicle. Pumps for space vehicles offer advantages beyond mass saving when propellant needs to be transferred from pre-positioned tanks or from in situ propellant plants. Space vehicles currently use tanks pressurized to 200-300 psi( MPa). These tanks are somewhat heavy, are very expensive and require propellant management devices to keep the propellant from sloshing around in the zero gee environment. The pump allows for lightweight, low-pressure tanks and the pump can be stopped with one chamber full of fuel so that when the spacecraft starts, the fuel will settle to the bottom of the tank. In addition, any leaks from the main tank will involve lower leak pressures and reduced explosion hazards. The spacecraft tanks need not be spheroidal, and options such as low pressure drop tanks etc. become feasible.
Pump technology is also crucial for increasing specific impulse of chemical (either bipropellant or monopropellant) rocket engines using earth-storable propellants by means of higher combustion chamber pressure. Higher chamber pressure increases performance while making engines more compact. Aerojet has been studying and has demonstrated the possibility of increasing the performance of interplanetary and apogee insertion propulsion by employing the pump fed system .The total engine firing time for a typical interplanetary mission is on the order of 60 minutes.







CHAPTER 9
ADVANTAGES AND LIMITATIONS

Listed below are a number of pump advantages of pistonless pumps.
Safety
• Negligible chance of catastrophic failure because typical failure modes are benign.
• Leaks from the main tank involve lower pressures, coarser atomization, and lower explosion hazards than from high pressure propellants
• Easy to start up and shut down, similar to pressure fed systems. No spool up time required.
• Thrust can be modulated quickly, to steer, rendezvous, or reduce start/stop transient loads
• The pump can be run dry with no adverse effects. The pump can even purge the lines leading to the engine.
• Minimal pogo effect as tank pressure is decoupled from engine pressure.
• Unlike other pumps, no problems with seals, cavitation, whirl or bearings.
Reliability
• Check valves, level sensors and pneumatic valves can be made redundant if necessary. The check valves in particular can be made very reliable, while the pressurant supply and vent valves are small enough to allow redundancy. All these components are currently available as space qualified COTS components.
• The gas and liquid valves are only required to operate for about 100-1000 cycles, so the valves would not be subject to significant wear.
• No sliding parts, no lubrication, may be started after being stored for a long time.
• Not susceptible to contamination. Our prototype has been sitting in a rusty steel tank for a year and it still works fine.
• The pump can be started after being stored for an extended period with high reliability because it can use valves which have already been flight qualified.
• The pump can also be vented to a low pressure so as to reduce loads on propellant valves with seals subject to creep or degradation for long duration space flights.
• Overall vehicle reliability in emergencies should improve, because pump chambers allow limited propellant storage near the engines, that can be used even if upstream feedlines are damaged.
Performance
• It can be installed in the propellant tank to minimize vehicle size. Will not reduce volume of propellant tanks because pump chambers hold displaced propellant.
• Allow for design flexibility, arbitrarily shaped tanks can be located to control CG
• For application in a weightless environment, the pump can be designed to have at least one chamber full at engine cutoff, thereby allowing for zero G restart with the propellant in the pump chamber providing the ullage thrust. This means that the propellant settling maneuvers and propellant control devices in the main tank are not required.
• The pump also allows for efficient motor throttling with a response time on the order of the pump cycle time, that is 2-5 seconds, with much faster thrust ramp-up with a full chamber (<0.1 second if desired), and tail-off, if it is acceptable to waste a modest amount of pressurant). The pump works well at flow rates from zero to full flow, so it can be used to provide pressurized propellant for attitude control
• If the pump is combined with an injector which can be partially shut down, very deep throttling can be achieved.
• The pump vent gas can provide roll control or be diffused and/or vented to both sides of the vehicle to minimize inadvertent application of thrust. The fraction of the pump gas vented at high pressure is more than enough to pressurize the main tank, for tank pressures less than roughly 1/3 of pump discharge pressure).
Cost
• The pistonless pump is much less expensive than turbopumps.
• The pump can be scaled up or down with similar performance and minimal redesign issues.
• Low risk development; pump technology has been demonstrated and prototypes have been built and tested.
• The manufacturing tolerances need not be tight.
• Pump and vehicle use inexpensive materials and processes in their construction

LIMITATIONS
The pistonless pumps have disadvantages along with such fine advantages.
• They cannot pump to higher pressure than drive gas (area ratio is 1:1)
• They cannot use either a staged combustion or expander cycle.
• A gas generator cycle is also difficult to integrate with the pistonless pump.
• The generated gas must be chemically compatible with both the propellants.
• This gas generator lowers the Ignition start period of the engine.














CHAPTER 10
CONCLUSION
The pump has been shown to be a viable alternative to turbopumps, with a comparable thrust to weight ratio. It is clear that the pistonless pump will cost at least 10 times less than a turbopump. It is also clear that the pistonless pump will be more inherently reliable than a turbopump, with no issues related to bearings, seals or vibration. Further optimization of the pump design will result in reduced cycle times and better pump thrust to weight ratios. One potential use for the pump would be to pump liquid Nitrogen or liquid Helium through a combustion chamber mounted heat exchanger to provide the gas to operate other versions of the pump which would be pumping propellant.

















REFERENCES
1. STEVE HARRINGTON. (2003) ‘Pistonless Dual Chamber Rocket Fuel Pump: Testing and Performance” ,AIAA 2003 - 4479, Joint Propulsion Conference, Huntsville, AL.
2. STEVE HARRINGTON. (2010), ‘Pistonless Pump System for Accelerated Development of a Heavy Lift LOX Hydrocarbon Engine’, AIAA-2010-7131 Joint Propulsion Conference, Nashville TN.
3. STEVE HARRINGTON. (2010), ‘High Performance Lox Hydrogen Upper Stage with Pistonless Pump’, AIAA 2010-8873 Conference & Exposition 30 August - 2 September 2010, Anaheim, California.
4. GEORGE P. SUTTON. (2001), ‘Rocket Propulsion’, Seventh Edition, pp.197–264.



SIBIN K GEORGE

Revision as of 11:06, 1 June 2012

A Pistonless pump is a type of pump designed to move fluids without any moving parts other than three chamber valves.

The pump contains a chamber which has a valved inlet from the fluid to be pumped, a valved outlet - both of these at the bottom of the pump, and a pressurant inlet at the top of the pump. A pressurant is used, such as steam or pressurized helium, to drive the fluid through the pump.

Working cycle

The cycle is as follows:

  • The fluid enters and fills the chamber from the inlet valve. The outlet and pressurant valves are closed.
  • The inlet valve closes, the outlet and pressurant valves open. The presurant forces the fluid through the outlet valve.
  • As the chamber empties, the presurant valve closes and the inlet valve opens, followed by the outlet valve closing.
  • The cycle is repeated.

Application in rocketry

It is most commonly used[citation needed] to supply propellants to rocket engines. In this configuration there are often two pumps working in opposite cycles to ensure a constant flow of propellants to the engine.

The pump has the advantage over a pressure-fed system in that the tanks can be much lighter. Compared to a turbopump the pistonless pump is a much simpler design and has less stringent design tolerances.

See also


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