A feasibility study on using inkjet technology, micropumps, and MEMs as fuel injectors for bipropellant rocket engines

Control over drop size distributions, injection rates, and geometrical distribution of fuel and oxidizer sprays in bi-propellant rocket engines has the potential to produce more efficient, more stable, less polluting rocket engines. This control also offers the potential of an engine that can be throttled, working efficiently over a wide range of output thrusts. Inkjet printing technologies, MEMS fuel atomizers, and piezoelectric injectors similar in concept to those used in diesel engines are considered for their potential to yield a new, more active injection scheme for a rocket engine. Inkjets are found to be unable to pump at sufficient pressures, and have possibly dangerous failure modes. Active injection is found to be feasible if high pressure drop along the injector plate are used. A conceptual design is presented and its basic behavior assessed

Publications of the Jet Propulsion Laboratory, July 1961 through June 1962

Jpl bibliography on space science, 1961-196

Lasers and bubbles:Thermocavitation for needle-free jet injections

This thesis describes thermocavitation in microfluidic confinement, which is the generation of a vapor bubble by laser-heating of the liquid. During the growth of this bubble, it pushes the remaining liquid in the microfluidic channel out, creating a fast jet which can penetrate the skin. Therefore, this technique can be used to inject medication or other liquids, such as tattoo ink, without the use of a needle. Good control of the jet velocity requires understanding of the laser-liquid interaction, which is the focus of this thesis.The two most commonly used lasers, pulsed and continuous-wave (CW) lasers were compared. Both lasers were found to generate similar bubble dynamics, but the CW laser is slightly less efficient and reproducible. However, CW lasers are more affordable and smaller in size, which could increase their potential to be used in a commercial handheld device. To further investigate thermocavitation, numerical simulations of the laser heating were compared with experimental results of the CW-generated bubbles. These simulations suggest that nucleation always occurred when the maximum temperature was around 237 °C. Therefore, varying the laser beam size and power allows for control over the bubble dynamics.Absorption of the optical energy by a thin gold layer on the channel wall was investigated as an alternative to volumetric absorption by the liquid itself. Although this heating through the gold layer could generate bubbles and jets, it was less efficient and degradation of the layer occurred. Improvement through simulations and different choice of materials may overcome these problems.Finally, surface modifications were applied to the microfluidic channel in order to improve the jet dynamics. Alternating hydrophobic and hydrophilic stripes along the jet axis enable further control over the jet formation, through two influences: shaping the initial meniscus, as well as keeping the jet straight along the hydrophilic stripe. Overall, the results in this thesis contribute to the understanding and control of laser-generated bubbles in microfluidic confinement and the resulting jet. These results are vital for further development of laser-actuated jet injection.<br/

NASA contributions to fluidic systems: A survey

A state-of-the art review of fluidic technology is presented. It is oriented towards systems applications rather than theory or design. It draws heavily upon work performed or sponsored by NASA in support of the space program and aeronautical research and development (R&D). Applications are emphasized in this survey because it is hoped that the examples described and the criteria presented for evaluating the suitability of fluidics to new applications will be of value to potential users of fluidic systems. This survey of the fluidics industry suggests some of the means whereby a company may use a fluidic system effectively either to manufacture a product or as part of the end product

Manufacturing flexible light-emitting polymer displays with conductive lithographic film technology

We report on a new low-cost manufacturing process for flexible displays that has the potential to rapidly expand the market into areas that have traditionally been outside the scope of such technology. In this paper we consider the feasibility of using offset-lithography to deposit contacts for polymer light-emitting displays. We compare and contrast manufacturing criteria and present a case study detailing our initial results. It is expected that these developments will stimulate further progress in multilayer device fabrication. Cheap, flexible conductive interconnects have the potential to find applications in a wide variety of device structures. For the more challenging exploitation areas in multilayer devices, such as displays, it was found that the properties of conductive lithographic films were not optimal in their current form. Three parameters (conductivity, surface roughness and surface work function) were identified as critical to device fabrication. Calendering and electroless plating were investigated as methods to improve these properties. Both methods aimed to modify the surface roughness and conductivity, with the plating study also modifying the work function