Pistonless pump

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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.


        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.

Working cycle[edit]

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.

Pumping Rate[edit]

                   Rocket engines requires a tremendous amount of fuel high
                at high pressure .Often th pump costs more than the thrust 
                chamber.One way to supply fuel is to use the expensive
                turbopump mentioned above,another way is to pressurize fuel
                tank.  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 chamber is pressurized, and then the fluid is 
                delivered to the engine at a moderate flow rate under high 
                pressure. The chamber is then vented 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.

Application in rocketry[edit]

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.


             Nearly all of the hardware in this pump consists of pressure 
           vessels, so the weight is low.There are less than 10 moving parts ,
           and no lubrication issues which might cause problems with other 
           pumps. The design and constr. Of this pump is st, forward and no
           precision parts are required .This device has advantage over std.
           turbopumps in that the wt. is about the same, the unit,engg.and test 
           costs  are less and the chance for catastrophic failure is less.This 
          pump has the advantage over pressure fed designs in that the wt. of 
          the complete  rocket is much less, and the rocket is much safer 
          because the tanks of rocket fuel do not need to be at high pressure.the 
          pump could be started after being stored for an extended period with 
          high reliability.It can be used to replace turbopumps for rocket 
          booster opn. or it can be used to  replace  high pressure tanks for deep 
          space  propulsion.It can also be used for satellite orbit changes and 
          station keeping.


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 the propellants. 5}This gas generator lowers the Ignition start period of the engine.

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