INTRODUCTION: NASA have developed a Low cost rocket fuel pump which has Comparable performance to turbopump at 80-90% lower cost. Perhaps the most difficult barrier to entry in the liquid rocket business is the turbo pump. A turbo pump design requires a large engineering effort and is expensive to mfg. 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.
NECESSECITY: The turbo pumps used in rocket are very heavy,containing many rotating parts by which there are more frictional losses which more consumption of fuel there by decreasing the efficiency of the engine .Also, the maintainanace of such pump is, very important factor since the rocket has to remain stable in the space, is difficult and require complex methods for it. If this pump gets any fault then its repairance requires long time and also it is avery hectic task.So, there must be
such a device which
overcomes all the drawbacks of the turbopump as above. The pistonless pump is the solution for the problems faced by using turbopumps. They have only a drawback that they supply fuel with less pressure as compared to turbopumps.
DESCRIPTION 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. For more details on the pump and a discussion of the second-generation design see reference 1 or 8. 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.
THE DUAL PISTONLESS PUMP:
NASA has designed,built and tested a simple, light weight pump (dual pistomless pump) for use in liquid propelled rocket
where a
reliable pump with minimal moving parts is needed. This pump has the potential to reduce the cost and increase the reliability of rocket fuel pumps by a factor of 20 to 100.
WORKING:
Rocket engines requires a tremendous amount of fuel high at
high
pressure
chamber.One turbopump tank.
way
.Often to
mentioned
th
pump
supply
fuel
above,another
costs is way
more to is
than
use
the
the
to
thrust
expensive
pressurize
fuel
Pressurizing a large fuel tank requires a heavy , expensive
tank. However suppose instead of pressurizing entire tank, the main tank is drained into a small pump chamber which is then pressurized. To achieve steady flow, the pump system consists of two pump chambers such that each one supplies fuel for ½ of each cycle. The pump is powered by pressurized gas which acts directly on fluid. For each half
of the pump system, a chamber is
filled from the main tank under low pressure and at a high flow rate,
then
the the
chamber
is
pressurized,
engine
at
a
delivered
to
moderate
pressure.
The chamber is then vented
and flow
then rate
the
fluid
is
under
high
and cycle repeats.
The
system is designed so that the inlet flow rate is higher than the outlet flow rate.This allows time for one chamber to be vented , refilled and pressurized while the other is being emptied.A bread board
pump has been tested and it works great .A high version
has been designed and built and is pumping at 20 gpm and 550psi.
WORKING CYCLE
PISTONLESS PUMP FIGURE:
As shown in the above diagram , two cylinders are there , filled with the fuel from the main tank. This main tank is emptied in these two cylinders, these cylinders are pressurized by the high pressure tank,as shown.The high pressure tank pressurizes one cylinder of high pressure,as
shown,as soon as the cylinder is
emptied , it is vented, again it gets filled up from the main tank.The same cycle reapeats for the second cylinder.the cycle is such that, fuel is supplied by the cylinder one by one.ie. each cylinder supplies fuel for each half cycle.As one cylinder supplies the fuel other has enough time to refill.
APPLICATIONS: DEEP SPACE PROPULSION: NASA has a need for high power propulsion to land and spacecraft on the moons of Jupitor and beyond.this pump would allow these missions to go forward due to lower weight of the fuel tanks.
For
example,
to
land
on
Europa
with
a
hydrazine
monopropellant rocket , pump fed design would save 80% of the tank
weight
compared
to
a
pump
fed
design.Further
weight
savings could be achieved by heating the pressurant gas more, because the pressurant
would not be in contact with the propellant
for more
seconds . In addition ,the chamber could be
than a few
increased , saving engine weight and improving performance. 2. X PRIZE VEHICLE FUEL PUMP APPLICATION: For X-prize competitors, a the fuel pump will reduce the cost and increase the safety and reliability of their amateur manned vehicles.Sitting
on
top
of
tons
of
rocket
fuel
is
dangerous
enough,siiting on top if tons of rocket fuel at high pressure is even more so. Many of the competitors plan to use Hydrogen Peroxide(HTP)
and
jet
fuel
to
power
their
rockets.When
the
pump is used to pump HTP, it can decompose some of the fuel in a gas generator to run the pump. This saves a considerable amount of weight pressurant and main tankage. In addition , the factor on the low pressure tanks will be similar to the cost of the high pressure tanks alone.
PERFORMANCE VALIDATION:
A calculation of the weight of this type of pump shows that the power to weight ratio would be dominated by the pressure chamber and that it would be of the order of 8-12 hp per lb., for a 5 second cycle using a composite chamber. This performance is similar to state
of
the
art
gas-generator
turbopump
technology.
(The
F1
turbopump on the Saturn V put out 20 hp/lb) This pump could be run
until
dry,
so
it
would
achieve
better
residual
propellant
scavenging than a turbopump. This system would require a supply of gaseous or liquid Helium which would be heated by a heat exchanger mounted on the combustion
chamber before it was used
to pressurize the fuel, as in the Ariane rocket.. The volume of gas required would be equivalent to a standard pressure fed design, with a small additional amount to account for ullage in the pump chambers. The rocket engine itself could be a primarily ablative design, as in the NASA Fastrac, scorpious rocket or in recent rocket engine tests.
INSTALLATION FIGURE:
A proof of concept model of the pump has been constructed out of clear plastic and tested at low pressure. The results of the test are shown below.The pressure and flow are quite steady. The pump system is run with a Labview based computer program. There are two floats which are used to monitor the level in each pump chamber and each chamber uses a two solenoid valves, one to pressurize source and on to vent the chamber. The installation figure of the pistonless pump is shown in the above figure. The
high pressure cylinder used for pressurizing fuel,is installed at the bottom of the rocket,shown in green colour in the figure.And above this cylinder further assembly is mounted as shown in the first diegram. Thus the figure shows that the installation is very easy as compared to that of the turbo pump.
WORKING MODEL OF ROCKET FUEL PUMP:
The pump shown is equipped with electronic level sensors and air cylinder actuated ball valves. The pump works as predicted and it will be easy to reconfigure it to pump LOX and jet fuel.this type of pump will make rocket propulsion systems much more reliable and less expensive than that
of
the
turbo
jet
pump.
FLOW AND PRESSURE DATA FOR ROCKET FUEL PUMP:
The above graph shows the variation of the flow of fuel through both of the cylinders .It shows that as one cylinder gets emptied the other one gets filled up and fuel is supplied by each cylinder to the engine
for each half cycle. As one cylinder gets emptied the
other one gets filled up , thus giving an uninterrupted fuel
supply
to the engine. Also, the time required for the refill of the fuel in the cynlinder is sufficient to supply fuel for next half cycle. A video of the pump in action is also available.The is steady as well and as the design is improved, the flow and pressure will be steadier. This pump is similar to one mentioned in 1960 in Exploring the Solar System by Felix Godwin p-21 p-22 and to one patented
by Sobey,(3,213,804)
Jim
Blackmon
and Eric Lanning
(6,314,978) A second generation version (patent pending) that is lower in weight (12 hp/lb) has been designed and built and is now being tested. The first prototype is designed to work with our Atlas Vernier. It provides 20 GPM at 600+ psi and it is made of stainless steel
and
Teflon
to
be
compatible
with
all
common
rocket
fuels(LOX,RP-1, H2O2, hydrazine etc). Check this page soon for test results. We plan to build a couple of flight ready versions of this pump to pump LOX and
kerosene and fly it on one of our
Atlas vernier powered rockets This rocket will be able to acheive an altitude of over 100 miles
ADVANTAGES:
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.
•
The pump is failure tolerant. A small leak in one of the check valves will only increase the pressurant consumption of the pump, it will not cause a pump failure. Software can be designed to keep a pump with redundant valves and sensors operational, despite failed sensors or valves.
•
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 1001000 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).
DISADVANTAGES: The pistonless pumps has disadvantages along with such fine advantages. 1.They cannot pump to higher pressure than drive gas (area ratio is 1:1) 2.They cannot use either a staged combustion or expander cycle. 3.A gas generator cycle is also difficult to integrate
with the pistonless
pump. 4.The generated gas must be chemically compatible with both propellants. 5.This gas generator lowers the Ignition start period of the engine.
the
CONCLUSION: The most significance of property of Pistonless pump that makes them different from that of turbo pump ,is the absence of piston. This is the most unique technique.In this ,no. of rotating parts is very less as compared to that of turbopump. Also, it’s installation is very easy.and moreover, it is light weight than turbo pump.So, it has less losses and improves,rather increases efficiency of engine.Also, it is much economical than turbopump. The only drawback of pistonless pump is that, that it cannot supply high pressure fuel and also,it cannot have stage combustion or expander cycle,further, it has no vibrations.
BIBLOGRAPHY: 1}Theory Of Rocket propulsion (By R.H.Boden) 2}Book Of Rocket Propulsion
(By zechosloviky)
3}Mechanics Of Thermodynamics Of propulsion (By Philip Hill,Call Peterson) 4}http://www.kahuna.sdsu.edu 5}www.flowmetrics.com 6}www.xcor.com
INDEX
SR NO.
TOPICS
PAGE NO.
1}
INTRODUCTION
1
2}
NECESSITY
2
3}
DUAL PISTONLESS PUMP
2
4}
WORKING OF THE PUMP
3
5}
DIAGRAM OF PISTONLESS PUMP
4
6}
ADVANTAGES
6
7}
APPLICATIONS
7-8
8} 9}
PERFORMANCE VALIDATION ISTALLATION IN ROCKET
9 10-11
10}
WORKING MODELOF THE PUMP
12-13
11}
GRAPH OF FLOW RATE VS. TIME
14-15
12}
DISADVANTAGES
16
13}
COCLUSION
17
14}
BIBLOGRAPHY
18
ABSTRACT:
Pistonless pump for rocket has been proved to be the most economical than piston pump or turbopump. In pistonless pumps, piston is absent. It has very much less rotating parts than that of piston pumps or turbo pumps. So, it has less friction losses and there by it helps to improve the efficiency of the engine considerably.They
can
be
easily
installed
in
the
rocket
than
turbopumps.Also,it reduces the weight of rocket. This article discusses the working , advantages of pistonless pump over turbopump. Pistonless pumps are 80-90% economical than that of piston pump or turbo pumps.Nasa has manufactured such kind of pump and tested it actually,and they found it works conveneiently.
