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PSAS Propulsion Team is building a reciprocating piston pump for liquid-fueled motors.

#Pump Description#
The pump under development uses OTS double-acting hydraulic cylinders with a high-pressure gas against the top side to pressurize the fuel and a spring return attached to the cylinder rods to refill after each discharge cycle.

#To-Do#

 - pull trigger on distance sensors, relays and optoisolators for the McNames TI board.


#Pump System Parameters#
Parameters identified so far in the pump system are as follows:

<!--
[[!table  data="""
Term | Meaning | Value
[[!teximg code="P_F"]] | High pressure fuel outlet. | 2000 psi. (13.79 E6 Pa)
[[!teximg code="D_S"]] | Diameter of piston face touching steam. | UNDEFINED
[[!teximg code="D_F"]] | Diameter of piston face touching fuel | UNDEFINED
[[!teximg code="A_F"]] | Area of piston face touching fuel. | UNDEFINED
[[!teximg code="P_{H_2O\emph{g}}"]] | Steam pressure. | UNDEFINED
[[!teximg code="\emph{f}"]] | Pump cycle frequency. | 1/s
[[!teximg code="\rho_k"]] | RP-1 density. | 810-1020 kg/m^3
[[!teximg code="\overset{\centerdot}{m}"]] | Mass flow, kg/s. | 0.1 kg/s
[[!teximg code="\emph{lg}"]] | Length of piston throw. | 0UNDEFINED
[[!teximg code="\sigma_{allowed}"]] | Max allowed stress in piston rod.
[[!teximg code="F_{op}"]] | Operating Force | UNDEFINED
"""]]
-->

#Component Sourcing#

To control the gas solenoids, we need to acquire relays, optoisolators and proximity sensors so that the pump controller knows where in its cycle it is at any point. All part numbers are for the Digi-Key catalogue.

Requirements: 2 Hz operation of relays, piston throw = 3.5 inches.

 - H11L1-MQT-ND, an optocoupler.
 - 425-2616-5-ND, a distance sensor (10 cm, in excess of requirements)
 - PB365-ND, a relay. Rated for 1800 ops/hr, which translates to .5 Hz. However, not rated in ops/second, so it may be possible to drive them fast for a brief period of time. Keith may have suggestions on this topic. Haven't found anything better on Digi-Key and am tired of looking. Getting ready to order these. They're cheap, so we can fry them and replace later.

#Parameter Relationships#

[[!teximg code="F_{op} = A_F * P_F = A_S * P_S \Rightarrow D_S = \sqrt{\frac{P_F}{P_S} * D_F^2}"]]

This, however, is a lie. There are frictional and spring forces working against the pump. In the part of the pump's cycle where the steam side cylinder volume is expanding, the force required to drive fuel is approximately:

[[!teximg code="P_S * D_S^2 = P_F * A_F + F_f + k\Delta x"]]

[[!teximg code="\emph{lg} = \frac{4 * \overset{\centerdot}{m}}{\pi * D_F^2 * \emph{f} * \rho_K}"]]

[[!teximg code="\left[P_{H_2O\emph{g}} * D_S^2 = P_F * D_F^2 \right] < \sigma_{allowed} * D_{rod}^2"]]


#Random Thoughts#
 See the [[cooling]] page for discussion on the motor cooling portion of the implemented system.

Propulsion Meeting and Project Updates
[[!inline rootpage="news" pages="news/* and !news/*/* and tagged(propulsion)" archive="yes" sort="title" reverse="yes" template="titlepage"]]

##Scope##

It is clear that the rocket engine + steam pump system is a delightfully complex problem, encompassing our favorite areas of fluid flow, mass flow, thermodynamic analysis and power systems. For the forseeable future, we should focus our efforts on developing a proof of concept (POC) pump system. The system as described in the 7/12 general meeting encompasses:

 - Combustion Chamber (McDonald's powered)
 - H<sub>2</sub>O (g) Accumulator
 - Steam Manifold
 - Controller (this is its own design challenge that the Controls team might be interested in tackling as a break from 6DoF)
 - Steam Cylinders
 - Fuel Cylinders (commercially sourced if possible)
 - High Pressure Fuel Manifold
 - Flow Regulator

##Off-the-Shelf Fuel Analog##
Since RP-1 is merely specially refined kerosene, we plan on running OTS kerosene to begin with.  When the system is working to spec we'll switch to RP-1 to see what else there is to learn.