Engineering Papers⌕ Search

SEARCH · Engineering Papers

Results for “Wire”

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.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 127 records · Page 7
All sourcesNASA NTRSDOE OSTI
NASA NTRS2012

In-Situ Wire Damage Detection System

An In-Situ Wire Damage Detection System (ISWDDS) has been developed that is capable of detecting damage to a wire insulation, or a wire conductor, or to both. The system will allow for realtime, continuous monitoring of wiring health/integrity and reduce the number of false negatives and false positives while being smaller, lighter in weight, and more robust than current systems. The technology allows for improved safety and significant reduction in maintenance hours for aircraft, space vehicles, satellites, and other critical high-performance wiring systems for industries such as energy production and mining. The integrated ISWDDS is comprised of two main components: (1) a wire with an innermost core conductor, an inner insulation film, a conductive layer or inherently conductive polymer (ICP) covering the inner insulation film, an outermost insulation jacket; and (2) smart connectors and electronics capable of producing and detecting electronic signals, and a central processing unit (CPU) for data collection and analysis. The wire is constructed by applying the inner insulation films to the conductor, followed by the outer insulation jacket. The conductive layer or ICP is on the outer surface of the inner insulation film. One or more wires are connected to the CPU using the smart connectors, and up to 64 wires can be monitored in real-time. The ISWDDS uses time domain reflectometry for damage detection. A fast-risetime pulse is injected into either the core conductor or conductive layer and referenced against the other conductor, producing transmission line behavior. If either conductor is damaged, then the signal is reflected. By knowing the speed of propagation of the pulse, and the time it takes to reflect, one can calculate the distance to and location of the damage.

Williams, Martha↗
NASA NTRS2018

Update - Body of Knowledge (BOK) for Copper Wire Bonds

Copper wire bond technology developments continue to be a subject of technical interest to the NASA (National Aeronautics and Space Administration) NEPP (NASA Electronic Parts and Packaging Program) which funded this update. Based on this new research, additional copper bond wire vulnerabilities were found in the literature - Crevice corrosion, intrinsic degradation of palladium coated copper wire, congregation of palladium near ball bond interface leading to failure, residual aluminum pad metallization impact on device lifetimes, stitch cracking phenomena, package delamination's that have resulted in wire bond failures and device failure due to elemental sulfur. A search of the U.S.A. patent web site found 3 noteworthy patents on the following developments: claim of a certain IMC (Intermetallic Compound) thickness as a mitigation solution to chlorine corrosion; claim of using materials with different pHs to neutralize contaminants in a package containing copper wire bonds; and a discussion on ball shear test threshold values for different applications. In addition, an aerospace contractor of military hardware had a presentation on copper bond wires where it was reported that there was a parametric shift and noise susceptibility of devices with copper bond wires which affected legacy design performance. A review of silver bond wire (another emerging technology) technical papers found that an electromigration failure mechanism was evident in device applications that operate under high current conditions. More studies may need to be performed on a comprehensive basis. Research areas for consideration are suggested, however, these research and or qualification/standard test areas are not all inclusive and should not be construed as the element (s) that delivers any potential copper wire bond solution. A false sense of security may occur, whenever there is a reliance on passing any particular qualification, standard, or test protocol.

Rutkowski, E.↗
NASA NTRS2020

Status of Analysis and Manufacturability of Superconducting Wires with Low AC Losses

Superconductors can carry an order-of-magnitude higher current than room temperature copper wires and can do so with two orders-of-magnitude lower alternating current (AC) electrical losses. These advantages underlie our estimates that turboelectric propulsion of large aircraft can be enabled by superconducting machines. However, even the much smaller losses of superconductors pose thermal management issues at the low temperatures required for superconductivity, and predicting those losses and validating the predictions has been a developing process at NASA Glenn Research Center over the last decade. Since Glenn’s earliest assessments of the feasibility of fully superconducting machines for turboelectric propulsion, the available models of AC losses in superconductors have changed significantly, as well as the state of development of superconducting wire for the coils of electric machines. While the models available to us have improved significantly, the value of the AC losses predicted by these models have only increased as more fidelity was developed. The fabrication of medium temperature superconducting wires (Tc near 40 K) has advanced, and wires can be produced with finer filaments and tighter twisting than a decade ago. However, the ideal wire configurations, developed decades ago for low temperature superconductors (Tc < 25 K), still elude manufacturers of medium and high temperature (Tc > 77 K) superconductors. This report discusses the developments, the current limitations, and the expectations that future configurations of superconducting wire can yet be produced that will provide suitably low AC losses for the aircraft propulsion application. The report presents a basic discussion of the types of AC losses in superconductors, followed by a discussion of the evolution of our understanding of the practical consequences of those AC losses. Next, there is a discussion of the superconducting wire configurations that have been developed, which were partially guided by that understanding. A brief discussion of the modes of removing the heat produced by the losses is presented. Lastly, a comparison is presented between losses in currently available MgB2 wire and other important cases, including copper at room temperature, copper at liquid hydrogen temperature, and expected future MgB2 wire. Room temperature copper has 100 times the loss of today’s MgB2 and 300 times the expected loss of future MgB2. That implies we can expect much higher efficiency from fully superconducting machines than from machines with copper stators, and high efficiency targets remain the driver behind investment in MgB2 development and medium temperature superconductor research.

superconducting motors↗
NASA NTRSDate not supplied

Re-Architecting the NASA Wire Derating Approach

• Design of wiring for aerospace vehicles relies on an understanding of “ampacity,” which refers to the current carrying capacity of wires, individually or in wire bundles. • Designers rely on standards to derate allowable current flow to prevent exceedance of wire temperature limits due to resistive heat dissipation within the wires or wire bundles. Designers select wire sizing and circuit protective device settings/sizing based on the standards. • Exceeding the wire temperature rating can result in electrical, physical, and/or chemical degradation of the wiring insulation and conductor which could lead to a catastrophic failure. • These standards can add considerable margin, in some cases underestimate the margin and are based on empirical data that is no longer available for review.

Steven L Rickman↗
DOE OSTI2019

Diameter Quality Control of Nb 3 Sn Wires for MQXF Cables in the USA

During this project, the 0.850 ± 0.003 mm Nb 3 Sn wires for the low-beta quadrupole magnets 'MQXFA' procured for the U.S. LHC Accelerator R&D Program (LARP) and the U.S. High Luminosity LHC Accelerator Upgrade Project (US HL-LHC AUP, or simply AUP) are received at Lawrence Berkeley National Laboratory (LBNL). There, the wires are respooled and then fabricated into Rutherford cables for winding coils. As part of the quality control program, AUP obtains from the wire manufacturer values of the maximum, average, minimum, and standard deviation of the two orthogonal axes, which are assessed prior to shipment approval. At LBNL, a dual-axis optical micrometer is used to measure the wire diameter of each spool every ~30 cm prior to cabling. This helps decide whether wire pieces with abnormal diameters should be distributed across the cable cross section, in order to improve cable parameter quality and mechanical stability consistency. This paper presents: 1) diameter data of LARP cables and of the first AUP cables made using wires acquired under LARP; 2) our deviation acceptance/rejection justification; and 3) the impact of wire diameter statistics on cable fabrication.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
DOE OSTI2019

Reel-to-Reel Heat Treatment, Microstructure, and Superconducting Properties of Jelly-Roll Nb{sub 3}Al Superconducting Wire

In this work, we utilized the jelly-roll method to make a single-filament Nb{sub 3}Al precursor long wire, combining with a homemade reel-to-reel rapid heating and quenching (RHQ) equipment, and consequently the high-performance Nb{sub 3}Al superconducting wires had been prepared. By investigating the heating current and wire moving speed, the optimized RHQ heat treatment conditions of this Nb{sub 3}Al wire were obtained. The results suggest that the T{sub c} for the Nb{sub 3}Al superconducting wire is up to 17.4 K and the non-Cu critical current density (non-Cu J{sub c}) reaches 1238 A/mm{sup 2} at 4.2 K and 12 T, which indicates the bcc-phase Nb–Al supersaturated solid solution has already been generated. Considering the Nb{sub 3}Al precursor wire with a large thickness of Al layer, about 690 nm, such high J{sub c} is quite unexpected. The SEM analysis presents that there is still some unreacted Nb and Nb{sub 2}Al phase in the superconducting wire, which may result from the inhomogeneity of Nb and Al foils. This work implies the Nb{sub 3}Al superconducting wire is promising to the application of high-field superconducting magnets.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
DOE OSTI2019

Study on Magnetization Losses in Soldered-Stacked-Square (3S) HTS Wires with 1 mm Width

Magnetization loss of high-temperature superconducting (HTS) wires is usually considered as a critical issue in power applications. In order to reduce magnetization loss, a narrow soldered-stacked-square (3S) HTS wire with 1 mm width is firstly proposed by our group. And as a novel HTS wire type, its magnetization loss should be significantly understood before applied in further application. In this study, we fabricate the 1-mm-wide 3S wires with 2+4c, 4+2c, and 6+0c structures, and evaluate their magnetization loss experimentally and numerically. In the fabrication process of the 3S wires, a newly suggested technology, laser cutting, is adopted. The results show that the magnetization loss in (4+2c)-wire is independent of the frequency under perpendicular field but dependent on the frequency under parallel field. This may be considered that both eddy current loss and coupling loss are contained in the case of parallel field, besides hysteresis loss. Moreover, the different structures of the 3S wires will not affect the magnetization loss under perpendicular fields, but influence the magnetization loss under parallel fields. And these numerical results for parallel field have larger deviations compared with measured magnetization loss because only hysteresis loss is considered in the numerical model. Finally, a considerable reduction of the magnetization loss in the 3S wire is observed in the comparison with that in the original tape.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
DOE OSTI2021

Controlling and Optimizing Photoinduced Charge Transfer across Ultrathin Silica Separation Membrane with Embedded Molecular Wires for Artificial Photosynthesis

Ultrathin amorphous silica membranes with embedded organic molecular wires (oligo( p -phenylenevinylene), three aryl units) provide chemical separation of incompatible catalytic environments of CO 2 reduction and H 2 O oxidation while maintaining electronic and protonic coupling between them. For an efficient nanoscale artificial photosystem, important performance criteria are high rate and directionality of charge flow. Here, the visible-light-induced charge flow from an anchored Ru bipyridyl light absorber across the silica nanomembrane to Co 3 O 4 water oxidation catalyst is quantitatively evaluated by photocurrent measurements. Charge transfer rates increase linearly with wire density, with 5 nm -2 identified as an optimal target. Accurate measurement of wire and light absorber densities is accomplished by the polarized FT-IRRAS method. Guided by density functional theory (DFT) calculations, four wire derivatives featuring electron-donating (methoxy) and -withdrawing groups (sulfonate, perfluorophenyl) with highest occupied molecular orbital (HOMO) potentials ranging from 1.48 to 0.64 V vs NHE were synthesized and photocurrents evaluated. Charge transfer rates increase sharply with increasing driving force for hole transfer from the excited light absorber to the embedded wire, followed by a decrease as the HOMO potential of the wire moves beyond the Co 3 O 4 valence band level toward more negative values, pointing to an optimal wire HOMO potential around 1.3 V vs NHE. Comparison with photocurrents of samples without nanomembrane indicates that silica layers with optimized wires are able to approach undiminished electron flux at typical solar intensities. Combined with the established high proton conductivity and small-molecule blocking property, the charge transfer measurements demonstrate that oxidation and reduction catalysis can be efficiently integrated on the nanoscale under separation by an ultrathin silica membrane.

photocurrent measurements↗
DOE OSTI2016

Experimental study of surface insulated-standard hybrid tungsten planar wire array Z-pinches at “QiangGuang-I” facility

The experimental results of the insulated-standard hybrid wire array Z pinches carried out on “QiangGuang-I” facility at Northwest Institute of Nuclear Technology were presented and discussed. The surface insulating can impose a significant influence on the dynamics and radiation characteristics of the hybrid wire array Z pinches, especially on the early stage (t/t{sub imp} < 0.6). The expansion of insulated wires at the ablation stage is suppressed, while the streams stripped from the insulated wires move faster than that from the standard wires. The foot radiation of X-ray is enhanced by increment of the number of insulated wires, 19.6 GW, 33.6 GW, and 68.6 GW for shots 14037S, 14028H, and 14039I, respectively. The surface insulation also introduces nonhomogeneity along the single wire—the streams move much faster near the electrodes. The colliding boundary of the hybrid wire array Z pinches is bias to the insulated side approximately 0.6 mm.

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗
DOE OSTI2022

Influence of twist pitch on hysteretic losses and transport J c in overpressure processed high J c Bi-2212 round wires

Abstract Bi-2212 is the only high field, high-temperature superconductor (HTS) available in the macroscopically isotropic, multifilament high J c round wire (RW) form capable of generating high uniformity fields with minimum-screening current errors. However, the heat treatment that enables impressively high J c (4.2 K, 30 T) values that can attain ∼5000 A mm −2 also produces significant filament bonding (bridging). Filament bridging appears to significantly enhance hysteretic losses of the filaments themselves by coupling neighboring, nominally independent filaments, enabling shielding currents to flow across multiple filaments as though they were one filament of much larger diameter. Wire twisting can be employed to reduce filament-to-filament eddy current coupling losses due to induced currents flowing across the matrix, but twisting is less effective in reducing increased losses from bridging. Here, we compare the twist-pitch dependence of the losses of overpressure processed (OP) high J c Bi-2212 RWs with partially bridged filaments to those found in OP Bi-2212 RWs with discrete, not-bridged filaments. We show that filament sub-bundles in standard, partially-bridged wires that have some superconducting connections between filaments can exhibit significant coupling (much larger effective filament diameter), but twisting still reduces their hysteretic losses to values close to or below the ITER Nb 3 Sn wire loss specification, even though Bi-2212 wires have significantly larger J c values. Although it has been reported that twisting can reduce wire J c by damaging filaments, we found no reduction in transport J c , even for nominal twist pitches of 12 mm in 0.8 mm diameter wires. Evaluation of more-recent, higher J c Engi-Mat powder wires showed that their reduced filament bridging and improved longitudinal connectivity significantly improved transport J c and reduced the J c normalized losses, signaling that J c can be further improved without commensurate increase in losses. This important result strengthens the argument for production of high field, low loss HTS magnets made with Bi-2212 RWs.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
DOE OSTI2023

High critical current STAR ® wires with REBCO tapes by advanced MOCVD

RE–Ba–Cu–O (REBCO, RE = rare earth) symmetric tape round (STAR ® ) wires of 1.5–2.5 mm diameter have been fabricated with 4–12 strands of symmetric REBCO tape made by advanced metal organic chemical vapor deposition (MOCVD). 1.5 mm diameter STAR ® wires made with just four advanced MOCVD tape strands are able to sustain nearly the same critical current (I c ) as 2.5 mm diameter wires made with 12 commercial-grade tape strands. An I c of 1070 A, corresponding to an engineering current density (J e ) of 597 A mm –2 , has been demonstrated at 4.2 K, 30 T in 1.5 mm diameter, four-strand wire at a bend radius of 15 mm. This I c value exactly matches the Ic expected from the lift factor of the tape strands used in the wire. The 2.5 mm diameter STAR ® wires made with 12 advanced MOCVD tape strands exhibit an I c of 1075 A at 77 K, self-field and sustained currents of 2500–2750 A at 4.2 K, 30 T before burnout, corresponding to a J e greater than 500 A mm –2 . Finally, these results show that the cost of STAR ® wires can be substantially reduced using fewer tape strands of high-performance advanced MOCVD tapes and that the superior bend performance of STAR ® wires can be maintained, even using 12 strands of advanced MOCVD tapes with 4 μm thick REBCO films.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
DOE OSTI2018

Effects of Chromium Additions upon Microstructure and Mechanical Properties of Cold Drawn Pearlitic Steel Wires

Cr-containing pearlitic steel wires were prepared through cold drawing and simulated galvanization process. Effect of chromium microalloying on microstructural and mechanical properties of the steel wires was investigated. Experimental results show that size of pearlitic colonies of the steel rods decreased as Cr content increased from 0.2 to 0.6 wt.%; meanwhile, interlamellar spacing was little affected because of isothermal phase transition in salt bath. The tensile strength of the pearlitic steel rods was increased from 1480 to 1550 MPa. The tensile strength of the Cr-containing cold drawn wires (ε = 1.58) was increased about 33%, and the torsion circle of the wires were about 15 with cleavage fracture. After annealing at 450 °C for 2 min, tensile strength of the wires increased, but torsion circle was decreased to less than 5. As the annealing time increased, the torsion circle of the steel wires with 0.2 wt.% Cr was improved to about 10 with cleavage fracture, while the torsion performance of the wires having high Cr contents remained low because of delamination fracture. The cementite platelets in Cr-containing wires turned into cementite crystal particles during cold drawing. Microstructure observation and thermal analysis have confirmed that thermal stability of cementite was enhanced with the increase of Cr content.

36 MATERIALS SCIENCE↗
DOE OSTI2019

Drawing Direction Effect on Microstructure and Mechanical Properties of Twinning-Induced Plasticity Steel During Wire Drawing

The effect of drawing direction on microstructure and mechanical properties in twinning-induced plasticity (TWIP) steel during wire drawing has been investigated to improve drawability for wire rod applications. The steel wires subjected to unidirectional (UD) and reverse-directional (RD) wire drawing were analyzed. The yield and tensile strength processed by the RD were slightly higher than those by the UD, whereas the ductility and drawability have inverse features, which is totally different from the results of plain carbon steel and Al wire. Although final shear strain of wires deformed by the RD is lower than that by the UD, the RD wires had a more complex stress history and a higher <111> texture component at the surface area, which encouraged twinning rate, resulting in fast exhaustion of ductility, finally earlier fracture of wires. In contrast to the materials deformed by mainly slip mechanism, the RD process cannot improve the ductility and drawability in TWIP steel due to the stress state dependency of twinning mechanism. Also, based on the different strengthening behaviors between pearlitic and TWIP steels during UD and RD, it is induced that microstructure and applied stress state simultaneously control the mechanical properties.

36 MATERIALS SCIENCE↗
DOE OSTI2022

A bi-layer barrier design for 122-type iron-based superconducting wires and tapes

Iron-based superconducting wires and tapes hold great promise for high-field magnet applications. A promising design for 122-type wires and tapes based on the powder-in-tube method is using silver and copper double-layer sheaths. For this design a heat treatment temperature below ~ 779 °C is required to prevent Ag-Cu liquid formation. However, this may be below the optimal heat treatment temperature for the critical current density, and still cannot prevent Ag-Cu interdiffusion occurring in the solid state. In this work we propose adding a niobium or tantalum or vanadium (or their alloys) barrier layer between the Ag and Cu to solve the Ag-Cu interdiffusion issue, given that the group-VB metals (vanadium, niobium, tantalum) are relatively inert to both Ag and Cu. To investigate the effectiveness of this design, BaFe 1.84 Co 0.16 As 2 wires and tapes with Ag/Cu and Ag/Ta/Cu sheaths, as well as Ba 0.6 K 0.4 Fe 2 As 2 wires and tapes with Ag/Cu and Ag/Nb/Cu sheaths, were fabricated. It was found that both the Ta and Nb layers kept integral after wire drawing, but after a large flat-rolling reduction the Ta layer broke while the Nb layer kept integral. In the tapes with Ag/Cu sheaths (without the Ta or Nb layer) Cu diffused through the Ag layer and into the powder cores during 740 °C heat treatment, while in the tapes with Ag/Nb/Cu sheaths the Nb layer effectively blocked Ag-Cu interdiffusion even at 900 °C. Further, this work demonstrates that Ta is a suitable barrier material for 122-type wires, while Nb is suitable for both wires and tapes. In this design using Ag/Nb (or Ta)/Cu sheaths, we can regard the outer Cu as the conductor matrix while the Ag and Nb (or Ta) serve as two layers of barriers that suppress reactions between the components. Thus, we call this design a “bi-layer barrier” design for 122-type wires and tapes.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
DOE OSTI2019

Highly Conductive Ag Paste for Recoverable Wiring and Reliable Bonding Used in Stretchable Electronics

Stretchable wiring and stretchable bonding between rigid chip/component and stretchable substrate are two of the key factors for stretchable electronics. Here, a low cost and highly stretchable paste is developed with Ag micro flakes and PDMS, which can be used to fabricate stretchable wirings and bondings under a low curing temperature of 100 °C with printing method. Recoverabilities as recovery time and recovery resistance of the wirings and bondings are defined and discussed. The wiring with a low resistivity of 8.7 × 10-5 ·cm shows much better recoverability than nanowire based wirings due to the flake nature of the Ag particles. When stretched to 50% and 100% of strain, the resistance of the patterned wiring increases to only 1.1 and 2.1 times, respectively. Moreover, the resistance of the wiring during 20% tensile cyclic test remains within 1.1 times even after 1000 cycles, showing long time durability. On the other hand, the paste is also used as a bonding material to assemble a zero-Ohm chip on the stretchable substrate to fabricate a stretchable demo, whose resistance increased to only 1.9 times when stretched to 50% of strain. The developed pastes can be expected to make various stretchable wirings, bondings and packaging structures by simple printing process, enabling mass production of stretchable electronic devices.

Li, Cai Fu↗
DOE OSTI2025

Increased electron, positron, and x-ray production from high intensity laser interactions using micro-wire targets

We report increases in energetic electrons, positrons, and x-rays emitted from high-intensity laser interactions (10 18−20 W/cm 2 ) with structured silicon micro-wires on the surface of a 1 mm gold converter target using a 10 ps laser pulse. A total of four different wire configurations are tested, where the gaps (7–28 μm) between the wires and the thicknesses (3–6 μm) of the wires are varied, while the height remains constant (⁠ ~25 μm). We observe the largest enhancement in electrons, positrons, and x-rays with the sparsest wire configurations. The electron temperature (T e ≈6 MeV) remains consistent across all shots, regardless of whether wires or planar targets are used. This suggests that the observed enhancement is due to increased laser light absorption by the accelerated electrons over a long scale length. Two-dimensional particle-in-cell simulations confirm that absorption is significantly enhanced with the wire target. Additionally, specific simulations examining laser pointing on different parts of the wire structure reveal that, while the final electron spectrum remains largely insensitive, the angular distribution is highly sensitive to these variations.

Bremsstrahlung↗
DOE OSTI2025

Oxide Dispersion Strengthened Ferritic Steel Wire Feedstock Development for Larger Format Additive Manufacturing (CRADA Final Report)

This CRADA project funded through DOE’s INFUSE program sought to demonstrate the viability of fabricating large, complex parts from oxide dispersion strengthened (ODS) steel with advanced manufacturing. Exhibiting excellent radiation tolerance and high mechanical performance at elevated temperatures, ODS steel is a promising structural material candidate for near-plasma components in fusion energy systems. Its use, however, has been limited by a lack of manufacturability. This project sought to produce ODS steel wire through a solid-state shear assisted extrusion process and then demonstrate that the wire can undergo controlled local melting while being welded with the final part sufficiently retaining the beneficial properties of ODS steel. This would allow the use of wire-arc additive manufacturing (WAAM) to manufacture large-scale ODS parts, even though ODS is currently only available as a powder. WAAM is a promising technique for producing components like the replaceable ARC vacuum vessel in CFS’ fusion reactor design. Meanwhile, this project will also expand PNNL’s capability in producing custom wire feedstock with friction extrusion, enabling downstream large-scale manufacturing with WAAM and solid-state based additive manufacturing. The project achieved its goals of developing tooling and fixturing to produce ODS wire at smaller diameters than previous projects. Several small lengths of wire of 1.5 mm and 2.5 mm diameter in the range of 2.5-30 mm long were produced at tool temperatures that are known to cause ODS particle coarsening (~1200 °C). Fixtures and tooling for longer (>1 m) wires were developed but further process development is needed reduce tool temperature during extrusions and to increase wire length needed for WAAM testing and development.

36 MATERIALS SCIENCE↗
NASA NTRS1952

The Calculated and Measured Performance Characteristics of a Heated-Wire Liquid-Water-Content Meter for Measuring Icing Severity

Ground tests have been made of an instrument which, when assembled in a more compact form for flight installation, could be used to obtain statistical flight data on the liquid-water content of icing clouds and to provide an indication of icing severity. The sensing element of the instrument consists of an electrically heated wire which is mounted in the air stream. The degree of cooling of the wire resulting from evaporation of the impinging water droplets is a measure. of the liquid-water content of the cloud. Determination of the value of the liquid-water content from the wire temperature at any instant requires a knowledge of the airspeed, altitude, and air temperature. An analysis was made of the temperature response of a heated wire exposed to an air stream containing water drops. Comparisons were made of the liquid-water content as measured with several heated wires and absorbent cylinders in an artificially produced cloud. For one of the wires, comparative tests were made with a rotating-disk icing-rate meter in an icing wind tunnel. From the test results, it was shown that an instrument for measuring the concentration of liquid water in an air stream can be built using an electrically heated wire of known temperatureresistance characteristics, and that the performance of such a device can be predicted using appropriate theory. Although an instrument in a form suitable for gathering statistical data in flight was not built, the practicability of constructing such an instrument was illustrated. The ground-test results indicated that a flight heated-wire instrument would be simple and durable, would respond rapidly to variations in liquid-water content, and could be used for the measurement of water content in clouds which are above freezing temperature, as well as in icing clouds.

Neel, Carr B.↗