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Results for “Electrohydrodynamics”

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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At least 19 records
All sourcesNASA NTRSDOE OSTI
NASA NTRS1974

Electrohydrodynamic heat pipe experiments

Experiments with two electrohydrodynamic heat pipes are reported. Both devices employ an electromechanical flow structure for axial liquid flow and a capillary wicking structure for (1) collection of condensed liquid at the cooled end and (2) distribution of this liquid at the heated end. One device has circumferential grooving for the capillary structure and the other has feltmetal wicking. The experiments successfully demonstrate the electrohydrodynamic heat pipe concept. Compatibility of the two circumferential wick structures with an axial electromechanical flow structure is also demonstrated. A significant mismatch of the capillary groove and electrohydrodynamic pumping capabilities results in severe hydrodynamic burn-out limiting in the first heat pipe. Both devices have very poor over-all thermal conductances of the order of 1-2 W/deg C, reflecting the generally poor heat-transfer properties of the dielectric working fluids required in electrohydrodynamic heat pipes.

Jones, T. B.↗
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 NTRS2014

Electrohydrodynamic Printing and Manufacturing

An stable electrohydrodynamic filament is obtained by causing a straight electrohydrodynamic filament formed from a liquid to emerge from a Taylor cone, the filament having a diameter of from 10 nm to 100.mu.m. Such filaments are useful in electrohydrodynamic printing and manufacturing techniques and their application in liquid drop/particle and fiber production, colloidal deployment and assembly, and composite materials processing.

Aksay, Ilhan A.↗
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 NTRS1973

Research in electrohydrodynamics

An overview is presented in the form of publications for NASA research in electrohydrodynamics. Data cover basic electrohydrodynamics, management of liquids in zero gravity, continuum feedback control, and magnetohydrodynamics and ferrohydrodynamics.

Source record↗
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 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 NTRS1985

Electrohydrodynamics

Models of electrohydrodynamic processes involving liquids with poorly ionized solutes at high (applied) field strengths were developed and tested. Extant theories which account for the details of physico-chemical processes associated with charged interfaces deal mainly with low field strengths and fully ionized solutes. The model used to describe processes at high field strengths--the leaky dielectric--omits consideration of electric double-layers, adsorption at interfaces, and chemical processes involved in the dissociation and recombination of solute species. Thus, even though the model depicts some features associated with bulk fluid motion, it fails to give a comprehensive picture. One example of the shortcomings of both the classical model of eletrokinetics at low field strengths and the leaky-dielectric model for high field strengths is found in the field strength dependence of the mobility of small particles in apolar liquids. The research will provide a more general model of electrohydrodynamic phenomena capable of application in diverse circumstances.

Saville, D. A.↗
NASA NTRS1994

Role of dielectric constant in electrohydrodynamics of conducting fluids

Electrohydrodynamic sample distortion during continuous flow electrophoresis is an experiment to be conducted during the second International Microgravity Laboratory (IML-2) in July 1994. The specific objective of this experiment is the distortion caused by the difference in dielectric constant between the sample and surrounding buffer. Although the role of sample conductivity in electrohydrodynamic has been the subject of both flight and ground experiments, the separate role of dielectric constant, independent of sample conductivity, has not been measured. This paper describes some of the laboratory research and model development that will support the flight experiment on IML-2.

Rhodes, Percy H.↗
NASA NTRS2004

Assembly of Colloidal Aggregates by Electrohydrodynamic Flow: Kinetic Experiments and Scaling Analysis

Electric fields generate transverse flows near electrodes that sweep colloidal particles into densely packed assemblies. We interpret this behavior in terms of electrohydrodynamic motion stemming from distortions of the field by the particles that alter the body force distribution in the electrode charge polarization layer. A scaling analysis shows how the action of the applied electric field generates fluid motion that carries particles toward one another. The resulting fluid velocity is proportional to the square of the applied field and decreases inversely with frequency. Experimental measurements of the particle aggregation rate accord with the electrohydrodynamic theory over a wide range of voltages and frequencies.

Ristenpart, W. D.↗