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Results for “electrohydrodynamic forces”

Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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8 records
All sourcesNASA NTRSDOE OSTI
NASA NTRS1973

Electrohydrodynamic heat pipes.

An electrohydrodynamic heat pipe of radical design is proposed which substitutes polarization electrohydrodynamic force effects for capillarity in collecting, guiding, and pumping a condensate liquid phase. The discussed device is restricted to the use of dielectric liquids as working fluids. Because of the relatively poor thermal transport properties of these liquids, capillary heat pipes using these liquids have not been high performance devices. The employment of the electrohydrodynamic concept should enhance this performance and help fill the performance gap that exists in the temperature range from 250 F to 750 F for 'conventional' capillary heat pipes.

Jones, T. B.↗
NASA NTRS1972

Experiments with an electrohydrodynamic heat pipe

The experimental results with a working model of the electrohydrodynamic (EHD) heat pipe are presented along with descriptions of the experimental device and its operation. Conclusions reached are: (1) EHD flow structures can be used to provide liquid communication between the condenser and evaporator of a heat pipe. (2) The voltage provides a remote electrical servo linkage of possible use in certain thermal control applications. (3) At least one hybrid flow structure, utilizing capillary and electrohydrodynamic forces, has been found functional. Proposed further experiments are discussed.

Jones, T. B.↗
NASA NTRS1975

Application of electrohydrodynamic phenomena to space processing

The capabilities of electrohydrodynamic (EHD) unit separation, liquid handling/control, and mixing are introduced to industrial chemists and metallurgists, working on specific zero-gravity processes. Previously proposed zero-gravity applications of EHD are presented along with the prominent electrohydrodynamical force effects.

Jones, T. B.↗
NASA NTRS1972

An electrohydrodynamic heat pipe.

A heat pipe of new design, using an electrode structure to orient and guide the dielectric liquid phase flow, is proposed. Analysis indicates that the operation of the electrohydrodynamic heat pipe is in direct analogy to capillary devices, with the polarization force acting in place of capillarity. Advantages of these new heat pipes include greatly reduced liquid friction, electrohydrodynamically enhanced evaporation and condensation heat transfer, and a possible voltage-controlled on/off feature. Preliminary calculations indicate that relatively high performance devices are possible.

Jones, T. B.↗
NASA NTRS1982

Electrohydrodynamic (EHD) stimulation of jet breakup

Electrohydrodynamic (EHD) excitation of liquid jets offers an alternative to piezoelectric excitation without the complex frequency response caused by piezoelectric and mechanical resonances. In an EHD exciter, an electrode near the nozzle applies an alternating Coulomb force to the jet surface, generating a disturbance which grows until a drop breaks off downstream. This interaction is modelled quite well by a linear, long wave model of the jet together with a cylindrical electric field. The breakup length, measured on a 33 micrometer jet, agrees quite well with that predicted by the theory, and increases with the square of the applied voltage, as expected. In addition, the frequency response is very smooth, with pronounced nulls occurring only at frequencies related to the time which the jet spends inside the exciter.

Crowley, J. M.↗
NASA NTRS1971

Dielectric siphons.

The normally weak polarization force density, exerted on insulating dielectric liquids by a nonuniform electric field, is enhanced if high pressures are used. The nonuniform electric field acts as an elastic ?wall' to contain and guide the dielectric fluid. A general theory for these electrohydrodynamic (EHD) conduits has been developed. An illustrative example of the EHD conduits is the dielectric siphon consisting of two U-shaped electrodes held adjacent to each other by insulating nylon screws.

Jones, T. B.↗