Thermal Drilling Research Articles

Underwater microwave ignition of hydrophobic thermite powder enabled by the bubble-marble effect

Highly energetic thermite reactions could be useful for a variety of combustion and material-processing applications, but their usability is yet limited by their hard ignition conditions. Furthermore, in virtue of their zero-oxygen balance, exothermic thermite reactions may also occur underwater. However, this feature is also hard to utilize because of the hydrophobic properties of the thermite powder, and its tendency to agglomerate on the water surface rather than to sink into the water. The recently discovered bubble-marble (BM) effect enables the insertion and confinement of a thermite-powder batch into water by a magnetic field. Here, we present a phenomenon of underwater ignition of a thermite-BM by localized microwaves. The thermite combustion underwater is observed in-situ, and its microwave absorption and optical spectral emission are detected. The vapour pressure generated by the thermite reaction is measured and compared to theory. The combustion products are examined ex-situ by X-ray photo-electron spectroscopy which verifies the thermite reaction. Potential applications of this underwater combustion effect are considered, e.g., for detonation, wet welding, thermal drilling, material processing, thrust generation, and composite-material production, also for other oxygen-free environments.

The New Knowledge of Environmentally Friendly Joints Made by Thermal Drilling

The contribution deals with possibilities of new progressive technologies in materials joining processes. By using of friction, physical factors as temperature and thermal conductivity in joining, we can increase the quality of material joining and can join of various types of material. There is also shortage the production time, provide automation in operations is possible, spare of economical expenses and also we can protect the environment. The product increasing of automobile industry, pipe industry, development of mechanical products, materials, design of joining in civil engineering force the producers to accelerate the production and to utilize new technologies.

The Analysis of Chosen Material Properties at Thermal Drilling

The contribution deals with joining of materials and creating of bushes from aluminum materials, with using of new joining technologies by thermal drilling, it means by Flowdrill method. This method is using at joining of materials such as sheets, pipes, hollow profiles, where the thickness of material does not allow to make the drilling with enough number of threads. Also we can compare this thermal drilling technology with production of smooth cylindrical and conical bushings by forming technologies. This paper was made with cooperation with firm Commerc Service spol.s.r.o., Prešov.

Incapability of Drilling With a High-Power-Density Beam

This paper theoretically identifies the factors affecting the keyhole collapse during drilling with a high-power density laser or electron beam from fundamental principles of thermal physics. Laser drilling is widely used in components, packaging, and manufacturing technologies. The approach adapted in this paper is to probe the quasi-steady 1-D supersonic or subsonic flow behavior of the two-phase vapor-liquid dispersion in a vertical keyhole of varying cross section, paying particular attention to the transition between the annular and slug flows. Drilling with a pulsed laser beam can evidently change Mach number, ejected mass flux at the keyhole base, energy absorption and evolution in the keyhole, drilling speed, and surrounding pressure. The results find that thermal drilling is susceptible to becoming incapable for higher absorbed energy, drilling velocity, and Mach number, ejected mass flux at the keyhole base, and lower surrounding pressure resulting in a shock wave for a supersonic flow in the keyhole. A subsonic flow usually gives rise to keyhole collapse. The predicted results agree with physical intuition and exact closed-form solutions derived in the absence of friction, entrainment and energy absorption. Controlling the factors to enhance efficiency and quality of drilling is therefore provided in this paper.

Investigate the Effect of Pre-drilling in Friction Drilling of A7075-T651

Friction drilling is a non-traditional hole achieving method that is a clean, chip-less process, which is called thermal drilling, form drilling, flow drilling, and friction stir drilling. In this study pre-drilling friction drilling was investigated for improving the bushing shape of A7075-T651, which is a brittle cast material. During the process, surface roughness and bushing shapes were analyzed and generated frictional heat was measured by the virtue of thermocouples. Experiments were carried out to 4 mm and 6 mm in thicknesses of A7075-T651 aluminum alloy at 1200, 1800, 2400, 3000, and 3600 rpm spindle speeds, 20, 40, 60, 80, and 100 mm/min feed rates with using high-speed steel rotating conical tool, whose diameter is 8 mm. Consequently, the bushing shapes were advanced without cracks and petal formation in pre-drilling Friction drilling in comparison with without pre-drilling process. With increasing pre-drilled hole diameter the generated frictional heat was decreased. The achieved temperature was realized to be 1/2–1/3 of the melting temperature of the workpiece. Surface roughness values were decreased with decreasing or increasing both spindle speed and feed rate correspondingly.

A new thermal drilling system for high-altitude or temperate glaciers

AbstractFor ice-core drilling on high-elevation glaciers, lightweight and modular electromechanical (EM) drills are used to allow for transportation by porters or pack animals. However, application of EM drills is constrained to glaciers with temperatures well below the ice melting point. When drilling into temperate ice, liquid water accumulates in the borehole, hindering chip transport, filling the chip barrel and finally blocking the drill. Drilling into near-temperate ice is also problematic as pressure-induced melting can cause refreezing of meltwater on the drill which then easily gets stuck in the borehole. We developed a thermal drill compatible with the Fast Electromechanical Lightweight Ice Coring System (FELICS). The melting element consists of a coil heater, molded in an aluminum crown. Using the combined mechanical and thermal drill we obtained a 101 m surface-to-bedrock ice core from temperate Silvrettagletscher, Swiss Alps. The borehole with temperatures around 0°C was filled with meltwater. Power was supplied by two 2kW gasoline generators consuming a total of 70 L of alkylate fuel. Ice-core production rate was 1.8 mh−1. The drill produced non-fractured ice cores of excellent quality with a length of 70 cm and a diameter of 75–80 mm.

Thermal Drilling in Planetary Ices: An Analytic Solution with Application to Planetary Protection Problems of Radioisotope Power Sources

Thermal drilling has been applied to studies of glaciers on Earth and proposed for study of the martian ice caps and the crust of Europa. Additionally, inadvertent thermal drilling by radioisotope sources released from the breakup of a space vehicle is of astrobiological concern in that this process may form a downward-propagating "warm little pond" that could convey terrestrial biota to a habitable environment. A simple analytic solution to the asymptotic slow-speed case of thermal drilling is noted and used to show that the high thermal conductivity of the low-temperature ice on Europa and Titan makes thermal drilling qualitatively more difficult than at Mars. It is shown that an isolated General Purpose Heat Source (GPHS) "brick" can drill effectively on Earth or Mars, whereas on Titan or Europa with ice at 100 K, the source would stall and become stuck in the ice with a surface temperature of <200 K.

Internal structure and porosity of ice ridges investigated at «North Pole‐38» drifting station

Abstract The paper presents the investigation results of morphometric characteristics of three first-year ice ridges conducted in March–June 2011 at «North Pole‐38» drifting station. The height of the ice ridge sail ranged within 3.3–6.1 m; keel draft, from 10.2 to 18.9 m. These studies were conducted using electric thermal drilling with computer recording of the penetration rate. Boreholes were drilled along the cross‐section of the ridge crest at 0.5 m intervals. Cross-sectional profiles of ice ridges are illustrated. In each borehole, ice ridge porosity was calculated as the ratio of the length of all voids to total length of the borehole. Distribution of ice ridge porosity along the cross-section seems to be rather regular. Depth-wise distribution of volume content of solid ice phase is shown for the investigated ice ridges. Average thickness of consolidated layer of ice ridges ranged within 0.8 … 2.6 m.

Determining ground thermal properties using logs and thermal drill cutting analysis. First relationship with thermal response test in principality of Asturias, Spain

Abstract In this paper, values for thermal parameters are obtained in two distinct and complementary ways: the first is through the drill cuttings and the Gamma Ray log, and the second is through a conventional TRT. This study presents the theoretical framework of the cuttings thermal analysis, the Gamma Ray log in the borehole and the TRT used in the interpretation of experiments. Then cuttings, formations and borehole thermal parameters have been determined. Finally, these results have been compared with those obtained from the TRT study.

Method of investigation of internal structure of ice hummocks and stamukhas using the thermal drilling technique

Computer recording of thermal drilling rate of ice hummocks and stamukhas gives the objective information on their internal structure and basic morphometric characteristics. Methods of determination of the consolidation layer of ice hummocks and stamukhas and the thermal drilling data processing technique are considered in the paper. The reliability of determination of consolidated layer boundaries on the basis of the thermal drilling rate should be corroborated by the temperature measurements. To estimate the time spent for the ice hummock temperature measurement using the polyethylene tubes which are put into the boreholes and filled with the antifreeze, the experimental study of the borehole freezing rate was carried out depending on the temperature and salinity of ice. The results of experiments corroborating the existence of convection in the antifreeze are given. The used methods of ice hummock temperature measurement are discussed. The method of investigation of ice formations combining the thermal drilling technique and ice temperature measurement on the borehole wall enables to obtain the accurate data on the position of the lower boundary of consolidated layer, although it results in a smaller number of the boreholes.

Laser drilling in gas turbine blades

AbstractDrilling applications represent about 5 % of the industrial laser materials processing applications. Cooling holes in gas turbines for aircrafts as well as for power plants are one of the main applications. The improvement of productivity has led to several drilling strategies with respect to laser sources (thermal drilling and ablation drilling), the beam handling, beam distribution, and handling of the work piece, all of which contribute to the overall efficiency of the process and a high productivity. We present the successful development and implementation of a combination of laser systems with different pulse durations for drilling complex 3D geometries (see Fig. 1).

Optimization of Thermal Friction Drilling Using Grey Relational Analysis

The main purpose of this research is to study the optimal machining parameters for a novel process of thermal friction drilling on SUS 304 stainless steel. The experiments were conducted according to an L9 orthogonal array based on Taguchi experimental designs method, and the multiple performance characteristics correlated with surface roughness (SR) and bush length (BL) was investigated by grey relational analysis systematically and comprehensively. Moreover, the significant machining parameters that most intensively affected the multiple performance characteristic and the optimal combination levels of machining parameters associated with the thermal friction drilling on SUS 304 stainless steel were determined through the analysis of variance (ANOVA) and the response graph of grey relational grade. The main machining parameters of the thermal friction drilling such as friction angle, friction contact area ratio, feed rate, and drilling speed were selected to evaluate the effects on SR and BL. The experimental results show that the thermal friction drilling revealed beneficial effects on SR and BL for drilling processes. Moreover, the optimal machining parameters for multiple performance characteristics associated with SR and BL were attained. The developed thermal friction drilling avoids serious tool wears, enhances the surface quality of the machined hole, and prolongs the tool life significantly.

Thermal drill sampling system onboard high-velocity impactors for exploring the subsurface of Europa

Abstract The planned Europa Jupiter System Mission (EJSM) will provide a unique opportunity to place scientific instruments onto the surface of Jupiter’s moon Europa in the late 2020s. After the Galileo mission, this will be a long awaited chance to have a close glimpse into some of the mysteries of this moon. Care must be taken in the choice of in-situ science that will be undertaken on the surface. We present a novel approach to deliver scientific instruments into the subsurface layers of planetary ice: A thermal drill was developed which uses heat and mechanical drilling in combination to penetrate the ice. The objective of such an instrument is to penetrate the upper layers of Europa’s surface to reach zones where space weathering and Jupiter’s heavy radiation have not altered potentially biogenic material that might have been brought from the depths to the surface. This paper presents the concept of the thermal drill and test results from its prototype. In the second part of the paper, we study the possibility of integrating a melting probe as a sampling system in high-velocity penetrators. The use of a melting probe in such a mission scenario gives various advantages: For example, a melting probe is less sensitive to the high decelerations of the impacting penetrators since the number of moving parts is reduced. This sampling technique would extend the operational range of an impact penetrator, allowing it to reach zones well beyond the depths where organic matter might be altered by micro-meteoroids and radiation. The paper concludes with a forecast into what kinds of instruments could be integrated into such a mission.

Jet impingement onto a tapered hole: Influence of jet velocity and hole wall velocities on heat transfer and skin friction

AbstractJet impingement onto a hole with elevated wall temperature can be associated with the high‐temperature thermal drilling, where the gas jet is used for shielding the hole wall from the high‐temperature oxidation reactions as observed in the case of laser drilling. In laser processing, the molten flow from the hole wall occurs; and in the model study, the hole wall velocity resembling the molten flow should be accounted for. In the present study, gas jet impingement onto tapered hole with elevated temperature is considered and the heat transfer rates as well as skin friction at the hole wall surface are predicted. The velocity of molten flow from the hole wall determined from the previous study is adopted in the simulations and the effect of hole wall velocity on the heat transfer rates and skin friction is also examined. It is found that the Nusselt number and skin friction at the hole wall in the regions of hole inlet and exit attain high values. The influence of hole wall velocity on the Nusselt number and skin friction is found not to be very significant. Copyright © 2008 John Wiley &amp; Sons, Ltd.

Study of a thermal drill head for the exploration of subsurface planetary ice layers

The recently discovered water vapor plumes on Saturn's moon Enceladus, the polar caps of planet Mars and the possible ice volcanism on the Jovian satellites call for suitable techniques to explore deep ice layers of the solar system bodies. This paper presents a novel approach to deliver scientific probes into deeper layers of planetary ice. Several existing locomotion concepts and techniques for such probes are presented. After studying the mathematical framework of the melting locomotion process, melting tests with different head forms were done to evaluate the influence of the head's geometry on the melting process. This work led to a novel concept of a thermal drill head, using heat and mechanical drill in combination to penetrate the ice. We compare the performance of such a hybrid concept versus the melting penetration alone by a mathematical model and tests in ice with a prototype of the melting drill head.

Laboratory experiments and thermal calculations for the development of a next-generation glacier-ice exploration system: Development of an electro-thermal drilling device

A next-generation drilling system, equipped with a thermal drilling device, is proposed for glacier ice. The system is designed to penetrate glacier ice via melting of the ice and continuously analyze melt-water in a contamination-free sonde. This new type of drilling system is expected to provide analysis data in less time and at less cost than existing systems. Because of the limited number of parameters that can be measured, the proposed system will not take the place of conventional drilling systems that are used to obtain ice cores; however, it will provide a useful method for quickly and simply investigating glacier ice. An electro-thermal drilling device is one of the most important elements needed to develop the proposed system. To estimate the thermal supply required to reach a target depth in a reasonable time, laboratory experiments were conducted using ice blocks and a small sonde equipped solely with heaters. Thermal calculations were then performed under a limited range of conditions. The experiments were undertaken to investigate the effects of the shape and material of the drill head and heater temperature on the rate of penetration into the ice. Additional thermal calculations were then performed based on the experimental results. According to the simple thermal calculations, if the thermal loss that occurs while heat is transferred from the heater to ice (in melting the ice) is assumed to be 50%, the total thermal supply required for heaters in the sonde and cable is as follows: (i) 4.8 kW (sonde) plus 0 W (cable) to penetrate to 300 m depth over 10 days into temperate glacier ice for which the temperature is 0 °C at all depths and to maintain a water layer along 300 m of cable; (ii) 10 kW (sonde) plus 19–32 kW (cable) to penetrate to 1000 m depth over 1 month into cold glacier ice for which the temperature is −25 °C at the surface and 0 °C at 1000 m depth and to maintain a water layer along 1000 m of cable; and (iii) 19 kW (sonde) plus 140–235 kW (cable) to penetrate to 3000 m depth over 2 months into an ice sheet for which the temperature is −55 °C at the surface and 0 °C at 3000 m depth and to maintain a water layer along 3000 m of cable. The thermal supply required for the cable is strongly affected by the thickness of the water layer, cable diameter, and the horizontal distance from the ice wall at which the ice temperature was maintained at its initial temperature. A large thermal supply is required to heat 3000 m of cable in an ice sheet (scenario (iii) above), but penetration into glacier ice (scenarios (i) and (ii) above) could be realistic with the use of a currently employed generator.

A New Model to Calculate Friction Coefficients and Shear Stresses in Thermal Drilling

A new analytical model for thermal drilling (also known as friction drilling) has been developed. The model distinguishes itself from recent work of other investigators by improving on two aspects: (1) the new model defines material plastic flow in terms of the yield in shear rather than the yield in compression, and (2) it uses a single, variable friction coefficient instead of assuming two unrelated friction coefficients in fixed values. The time dependence of the shear stress and friction coefficient at the hole walls, which cannot be measured directly in thermal drilling, can be calculated using this model from experimentally measured values of the instantaneous thrust force and torque. Good matches between the calculated shear strengths and the handbook values for thermally drilling low carbon steel confirm the model’s validity.

Internal structure of ice ridges and stamukhas based on thermal drilling data

During the resent years (1996–2005) the Arctic and Antarctic Research Institute performed expeditionary research in marginal seas. One of the tasks consisted in the determination of morphometric characteristics of ice ridges and stamukhas with the help of thermodrilling, with recording of the rate using a computer. The record of the penetration rate of the thermodrill and the water column pressure in the borehole as a function of depth, as well as processing of the recorded data, enabled to get information about the boundaries of consolidated layer. Principles of interpretation of the records of penetration rate of the thermodrill are discussed. Depth-wise distribution of volume content of solid phase of ice is presented for ice ridges and stamukhas in the various regions. Methodological grounds are discussed, of the determination of this distribution, based on the results of averaging of the data obtained through thermodrilling. Internal structure of ice ridges and stamukhas is discussed, for the Pechora Sea, the Sea of Okhotsk, the Caspian Sea, the Sea of Azov and near-polar district of Arctic basin, as well as its consideration with respect to other literary sources. Based on the accomplished analysis of the internal structure of ice ridges and stamukhas of the shelf of the Sakhalin Island and the Pechora Sea, a conclusion was made, that the thickness of consolidated layer determined based on the rate of drilling, according to subjective perception of the operator, frequently proves to be overestimated. The ratio between average thickness of consolidated layer of ice ridges and average thickness of level ice which surrounds the same in the regions in question varies within the range of 0.83…1.63, about 1.2 on the average. For stamukhas this ratio varies within the range of 1.3…2.1, about 1.7 on the average. Average porosity of the investigated ice ridges varies within the range of 12–28%, of the stamukhas — 7–20%.

Deep drilling at Vostok station, Antarctica: history and recent events

AbstractDeep drilling into the ice sheet at Vostok station, Antarctica, was started by specialists of the Leningrad Mining Institute (since 1991, St Petersburg State Mining Institute) in 1970. Five deep holes were cored: hole No. 1 to 952 m; hole No. 2 to 450.4 m; hole No. 3G (3G-1, 3G-2) to 2201.7 m; hole No. 4G (4G-1, 4G-2) to 2546.4 m; and hole No. 5G (5G-1) to 3650.2 m depth. Drilling of hole 5G-1 is not yet complete. The deep drilling at Vostok station has had successes and problems. All the deep holes at Vostok have undergone at least one offset drilling operation because of problems with lost drills. These deviations were made successfully using a thermal drilling technique. Several drilling records have been achieved at Vostok station. The deepest dry hole, No. 1 (952 m), was made during Soviet Antarctic Expedition (SAE) 17 in 1972. The deepest fluid-filled hole, No. 5G-1, made by a thermal drill (TBZS-132), reached 2755 m during SAE 38 in 1993. The deepest fluid-filled hole in ice, No. 5G-1, was drilled with a KEMS-132 electromechanical drill and was stopped above Vostok Subglacial Lake at 3650.2 m depth during Russian Antarctic Expedition (RAE) 51 in 2006.

Microstructural Alterations Associated With Friction Drilling of Steel, Aluminum, and Titanium

Friction drilling, also called thermal drilling, is a novel sheet metal hole-making process. The process involves forcing a rotating, pointed tool through a sheet metal workpiece. The frictional heating at the interface between the tool and workpiece enables the softening, deformation, and displacement of work-material and creates a bushing surrounding the hole without generating chip or waste material. The bushing can be threaded and provides the structural support for joining devices to the sheet metal. The research characterizes the microstructures and indentation hardness changes in the friction drilling of carbon steel, alloy steel, aluminum, and titanium. It is shown that materials with different compositions and thermal properties affect the selection of friction drilling process parameters, the surface morphology of the bore, and the development of a highly deformed layer adjacent to the bore surface.