Pistonless pump

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.

The cycle is as follows:

Rocket engines requires a tremendous amount of fuel high at high pressure. Often the 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 550 psi.

It is most commonly used 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.

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