Penetration Angle Research Articles

Turning of High-performance Materials with Rotating Indexable Inserts

High-performance materials with excellent heat resistance are necessary to meet future demands on improving the efficiency of energy converting technologies in the field of power plant construction and aviation industry. Nickel base super alloys can meet these demands to a large extent. However, their excellent corrosion resistance and heat resistance as well as hardness and wear resistance have an adverse effect on the machinability with geometrically defined cutting edges. High local thermal and mechanical stress leads to short tool life and long non-productive time for the tool change. Along with a 90% decrease of cutting speed in comparison to conventional steel machining, cutting of nickel base super alloys demands for more efficient machining processes. One attempt to reduce thermal loads of the tool is machining with rotary tools, where a round indexable insert is mounted on a rotating axis. While machining the workpiece, the rotation of the cutting insert constantly exchanges the active cutting edge section. This allows for a better cooling of the temporarily inactive sections. Also tool wear is distributed equally along the circumference instead of using discrete positions only.In this paper two different types of rotary tools, a self-propelled rotary tool (SPRT) and an actively driven rotary tool (ADRT), are presented. In a series of experiments the influence of the modification of process parameters, penetration angle and tool rotation to the characterization of the surface area of the workpiece, stability of the cutting process and economic efficiency was investigated. Finally a process model was developed as a user-oriented guideline for turning the nickel base super alloy Inconel 718 with rotating indexable inserts.

THE EFFECT OF FLASH BOILING ON THE ATOMIZATION PERFORMANCE OF GASOLINE DIRECT INJECTION MULTISTREAM INJECTORS

In this work the effect of flash boiling on liquid breakup and atomization is first reviewed and then described in detail for the sprays produced by two high-pressure multistream gasoline direct injectors. They were operated at 120 and 200 bar pressure with a fuel injection duration of 0.8 ms into subatmospheric pressures between 1 and 0.1 bar and four temperatures between 20 and 100°C. The sprays were injected into an optically accessed chamber whose temperature and pressure were independently controlled to recreate the conditions found in an engine likely to cause flash boiling. Shadowgraph imaging with a single-shot charge-coupled device camera was applied to obtain images of the spray morphology under a matrix of the above conditions. The interaction between spray streams is particularly complex under flash boiling conditions being a function of the nature of the fuel and the geometry of the injector. In this investigation, three different fuels, regular RON-95 gasoline and single components fuels, n-heptane and iso-octane, were used with two different injectors, one with a 60 degree and the other with a 90 degree nominal external cone angle. In total, five variables were investigated: fuel pressure, ambient pressure, ambient temperature, fuel composition, and injector geometry. Once processed, the recorded images allowed measurement of spray tip penetration and cone angle. Qualitative data on the change in shape of the spray were also available. The results showed that flash boiling has potential to reduce droplet diameters and improve fuel vaporization; however, the associated change in spray shape must be taken into account to avoid problems with spray impingement.

Engine combustion network: Influence of the gas properties on the spray penetration and spreading angle

In this work, three Engine Combustion Network (ECN) single-hole nozzles with the same nominal characteristics have been tested under a wide range of conditions measuring spray penetration and spreading angle. n-Dodecane has been injected in non-evaporative conditions at different injection pressures ranging from 50 to 150MPa and several levels of ambient densities from 7.6 to 22.8kg/m3. Nitrogen and Sulphur Hexafluoride (SF6) atmospheres have been explored and, in the first case, a temperature sweep from 300 to 550K at constant gas density has been executed. Mie scattering has been used as the optical technique by employing a fast camera, whereas image processing has been performed through a home-built Matlab code.Differences in spray penetration related to spray orifice diameter, spreading angle and start of injection transient have been found for the three injectors. Significant differences have been obtained when changing the ambient gas, whereas ambient temperature hardly affects the spray characteristics up to 400K. However, a reduction in penetration has been observed beyond this point, mainly due to the sensitivity limitation of the technique as fuel evaporation becomes important. The different behavior observed when injecting in different gases could be explained due to the incomplete momentum transfer between spray droplets and entrained gas, together with the fact that there is an important change in speed of sound for the different gases, which affects the initial stage of the injection.

폐식용유 바이오디젤 연료의 분무특성에 관한 연구

This study was performed to investigate the effect of biodiesel derived from waste cooking oil on the spray behavior and macroscopic spray characteristics. To analyze quantitative characteristics of test fuels, injection quantity was measured at various injection pressures and the spray images of injected fuels in the pressurized chamber were obtained by using a high speed camera and image analysis system. Based on the measured spray images, the spray tip penetration and spray cone angle were investigated at various energizing timings and injection pressures. In this work, the experimental results showed that the injection quantity of waste cooking biodiesel indicated the higher quantities than diesel at high injection pressure. As the injection pressure was increased, the spray tip penetrations of biodiesel were higher value than diesel. The difference of penetration between biodiesel and conventional diesel fuel was reduced in accordance with the increase of injection pressure. Also, the spray angles of diesel were larger than that of biodiesel because diesel fuel has lower viscosity than biodiesel. In addition, the spray evolution processes of biodiesel fuel at various injection pressures and the elapsed time after the injection were compared to the conventional diesel fuel.

Spray Characteristics of Hydrotreated Biodiesel Blended Fuels

Hydrotreated biodiesel (HBD) would be one of the promising alternative fuels instead of current biodiesel. In this study, spray characteristics in terms of spray penetration and spray angle were conducted experimentally including calculated SMDs as well. The ambient pressures of 1, 3, and 5 MPa and injection pressures of 30, 80, and 130 MPa were introduced and the fuels employed were petro-diesel, and 2, 10, 20, 30, and 50% for hydrotreated biodiesel, respectively. The result of this study found that the more HBD blended diesels have the slightly shorter spray tip penetration lengths especially on the lowest injection pressure and at the highest ambient pressure, but have the larger spray angles and SMDs than petro-diesel. Consequently, this study found that HBD has a little bit merits and demerits of macro- and micro- spray patterns compared to petro-diesel.

Experimental investigation in an optically accessible diesel engine of a fouled piezoelectric injector

This case study is aimed to investigate how the injector fouling can influence both the injection system and engine performances. In particular, the presence of deposits in the nozzle of the injector could affect the injection system performance along its life. The investigation was carried out on transparent compression ignition engine equipped with the head of a commercial multi-cylinder engine and second-generation common rail injection system. Two indirect-acting piezoelectric injectors were tested: one new another fouled. Optical engine was fueled with diesel and tests were performed with engine running in continuous mode. Two operating conditions were investigated. The new and fouled piezo injectors were characterized by injection rate profiles. The injection and combustion phases were investigated by optical measurements. Two-color pyrometry was used to analyze the pollutants formation and exhaust emission. Experimental results showed that the fouled injector has slower dynamic response and it injects a smaller amount of fuel during the main event. It has shorter jets penetration and wider spray angle that affect in negative way the mixing formation and the combustion evolution. High temperature regions and high sooting flames are detected for the fouled injector. Therefore, it emits high nitrogen oxides and particulate matter at the engine exhaust.

Experimental study of the spray characteristics of USLD, methanol and DME on the swirl nozzle of a Stirling engine

The objective of this paper was to investigate the spray characteristics of methanol and dimethyl ether (DME) on the swirl nozzle of a Stirling engines by comparing with traditional ultralow sulfur diesel fuels (USLD) under different fuel injection rates and different surrounding back pressures in a constant volume pressure vessel. Under the test rig, the macroscopic and microscopic spray characteristics of the fuels were studied by a high speed camera and FAM Laser Particle Size Analyzer during the atomization process. The experimental results show that injection pressure and ambient pressure have a significant impact on the spray tip penetration and spray angles. Higher spray pressure makes the formation period of spray decrease and the penetration rate increase whereas higher back pressure inside the injection chamber leads to the shrinking of the spray angle. The atomization quality of DME under atmospheric back pressure is much better than that of methanol and ULSD while it becomes worse when ambient back pressure is higher than the saturated vapor pressure. Additionally, higher back pressure and a larger injection flow rate are beneficial to the atomization quality of ULSD, whereas those factors seem to have relatively small influence on the droplet size distribution of methanol.

Stress Mitigation Design of a Tubesheet by Considering the Thermal Stress Inducement Mechanism

Adoption of double-wall straight-tube steam generators (SGs) made of Mod.9Cr-1Mo steel is planned for next-generation fast breeder reactors (FBRs) in Japan. One of the major concerns with the SG is the structural integrity of the tubesheet. During a transient event, a maximum thermal stress may be induced by the temperature distribution in the tubesheet, and the magnitude of the stress depends on the configuration of the tubesheet. Therefore, the stress generation mechanism of a tubesheet was studied through finite element (FE) analysis. Semispherical tubesheet models were investigated for the first survey of the thermal stress mechanism. The calculated results of the semispherical tubesheet model indicated an extensive peak stress around the outermost hole. The recognized thermal stress mechanism of a semispherical tubesheet is as follows: (1) The dominant thermal stress is hoop stress caused by the temperature difference between the perforated and surrounding regions. (2) The thermal stress is insensitive to the size of the specific portion, although it is dominated by an interaction mechanism between the perforated and surrounding regions. (3) The stress concentration around the edge of the holes generates a peak stress. (4) The amplitude of the peak stress depends on the tubesheet penetration angle, and the stress concentration becomes greatest near the outermost hole. Based on the above stress generation mechanism, we proposed a stress-mitigated tubesheet, a center-flattened spherical tubesheet (CFST), as an improved configuration. The calculated peak stress of the CFST was smaller than that of the semispherical tubesheet. Further investigation revealed the detailed stress generation mechanism of the CFST during a thermal transient. There were, in fact, two different comparable thermal peak stress mechanisms observed for the CFST. Both the location and magnitude of the maximum peak stress depended on the steam temperature histories during the thermal transient. The radial stress caused by structural discontinuity, which was located at the outermost hole, depended on the rate (dT/dt) of the steam temperature change. The hoop stress caused by the interaction between the perforated and surrounding regions, which occurred at the first inner layer hole (with respect to the outermost layer holes) depended on the range (ΔT) of the steam temperature change.

Experimental Study on the Spray Characteristics of Diesel and Biodiesel (Jatropha Oil) in a Spray Chamber

The increasing industrialization and motorization of the world has led to a steep rise for the demand of petroleum-based fuels. Petroleum based fuels are obtained from limited reserves highly concentrated in certain regions of the world i.e. those countries that lack these resources are facing energy crisis. Hence it is necessary to look for alternative fuels which can be produced from resources available locally within the country such as biodiesel, alcohol and vegetable oil. The biodiesel is technically competitive with conventional petroleum derived diesel fuel and requires no changes in the fuel distribution system. For this reason and its biodegradability, use of biodiesel is considered a good alternative of fossil fuels. Injection process of biodiesel influences the atomization and dispersion of fuel in the combustion chamber. In this research work the influence of biodiesel on injection process and their impact on the air-fuel mixture preparation are studied. Spray characteristics of biodiesel (Jatropha oil) and diesel under various injection pressures were studied experimentally. Spray penetration and spray angle were measured in a spray vessel using a high speed video camera. The study shows the biodiesel gives longer spray tip penetration and spray angle are smaller than those of diesel fuels. The parameters like break up time and break up velocity were for biodiesel and diesel at various injection pressures. It was found that breakup time for biodiesel increases and breakup velocity decreases. Breakup velocity of biodiesel is less than diesel, this is due to higher sound velocity, density, viscosity and bulk modulus of biodiesel. High viscosity fuel suppresses the instabilities required for fuel jet to breakup and thus delays atomization and reduces fuel losses during injection. With the increase in fuel injection pressure, the breakup time for biodiesel is more than diesel, this is due its larger surface area of the spray and larger mixing time of biodiesel than diesel.

Spray Characteristics of Diesel and Biodiesel in Direct Injection Diesel Engine

Alternative fuels for diesel engines are becoming important due to the decrease of petroleum reservoirs and the increase of environment pollution problems. The biodiesel is technically competitive with conventional petroleum-derived diesel fuel and requires no changes in the fuel distribution system. Injection process of biodiesel influences the atomization and dispersion of fuel in the combustion chamber. In diesel Engine different tests have been performed to improve the efficiency in cycle, power, less emission, speed, etc. There are various methods of visualizing the combustion chamber in a Diesel engine. For visualizing spray characteristics of combustion chamber in Diesel engine the window of 10mm diameter hole, transparent quartz glass materials are used, which can with-stand 1500°C temperature and pressure of about 1000 bar and engine is hand cranked for conducting the experiments. Spray characteristics of palm oil methyl ester (POME) and diesel were studied experimentally. Spray penetration and spray angle were measured in a combustion chamber of DI diesel engine by employing high definition video camera and image processing technique. The study shows the POME gives longer spray tip penetration and spray angle are smaller than those of diesel fuels. This is due to the viscosity and density of biodiesel.

Study on the Effect of Standoff Distance on Processing Performance of Alumina Ceramics in Two Modes of Abrasive Waterjet Turning Patterns

Abrasive waterjet (AWJ) turning is an emerging technology, which plays an important role in machining cylindrical parts with the distinct advantages of negligible thermal effects and extremely low cutting force. This paper presents an experimental study of abrasive waterjet turning (AWJT) of Al2O3ceramics. The machining process and performance in terms of the depth of penetration (DOP), surface roughness (Ra) and actual impact angle (β) are discussed to understand the effect of standoff distance (SOD) on the processing performance at two different turning modes. Based on the results of these investigations, there is a significant change ofDOPandRaat differentSODin radial mode turning and the optimalSODof gaining maximumDOPand the minimumRais about 5.5mm.However, theDOPis nearly independent on theSODin offset mode turning. SmallerRaandDOPcan be obtained in offset mode. Furthermore, the results indicate that the roundness error of cylinder parts is probably improved with the properSODinterval in radial mode turning and it is suitable for machining cylinder part with considerably different radial size. The offset mode turning as the next operation after radial mode turning is recommended to process workpiece with excellent roundness. In this way, by understanding the effect ofSODon processing alumina ceramics, the paper establishes a good basis for developing strategies for optimizing processing parameters in order to generate the desired part geometry and achieve better surface quality.

Cutting of Nickel-Based Superalloys with Rotating Indexable Inserts

In this paper the technological basics of machining the nickel-based superalloy Inconel 718 with a self-propelled rotary tool and an actively driven rotary tool are presented. The advantages compared to conventional machining with fixed round indexable inserts are discussed. In a series of experiments the influence of the tool rotation and modification of the process parameters to the chip formation process and characterization of the surface area of the workpiece are investigated. By using a multitasking lathe with a milling spindle further experiments are conducted. Thereby the influence of the direction of the tool rotation, the relative speed between tool and workpiece and the variation of the penetration angles are analysed.

Experimental investigation concerning the influence of fuel type and properties on the injection and atomization of liquid biofuels in an optical combustion chamber

Due to the scarcity of fossil fuels and the future stringent emission limits, there is an increasing interest for the use of renewable biofuels in compression ignition engines. However, these fuels have different physical, chemical and thermodynamic properties affecting atomization, spray development and combustion processes. The results reported in this paper have been obtained by experimentation with a constant volume combustion chamber. The influences of physical fuel properties on injections under non-evaporating conditions are studied, using a pump-line-nozzle system from a medium speed diesel engine with injection pressures up to 1200 bar, by changing the fuel type and temperature. Experiments were conducted for diesel, biodiesel, straight vegetable oils and animal fats. Injection pressure and needle lift measurements were analyzed. A high speed camera was used to visualize the spray, which enabled us to study the spray penetration and spray angle. Our results show that the fuel temperature is an important parameter to control because it significantly affects the fuel properties. Both the injection timing and injection duration are affected by the fuel properties. The influences of these properties on the spray development were less pronounced. At low temperatures, a strongly deteriorated atomization of oils and fats was observed.

An Appraisal of Duct-Related Microwave Link Degradation in Nigeria

Drop in power (or field strength) of free-air radiowaves sometimes occur in line-of-sight paths within the radio horizon of the transmitter due to discontinuities in refractivity gradient. Field strength fading within the radio horizon may result from defocusing of the lobe pattern of the transmitter, and may simultaneously give rise to enhanced field strengths beyond the horizon, with potential for adverse interference on co-channel circuits and other degradation effects related to such anomalous propagation. These effects increase with the duct strength, which depends on the prevailing refractivity gradient within the duct. In a duct-prevalent region, anomalous propagation problems can be significant on terrestrial and slant earth-satellite paths, depending on the penetration angle and strength of the prevailing ducts. Studies have revealed considerable prevalence of surface ducts in Nigeria. This effort examines the climatic conditions that give rise to ducts and assesses their potential for degradation of microwave links in the country. The result based on analysis of clear-air meteorological data shows prevalence of strong surface ducts with maximum and mean penetration angles of 15 milliradians and 6-8 milliradians respectively. Thus, high-elevation slant earth-satellite paths may not be affected by duct-related propagation problems in Nigeria, but low-elevation terrestrial microwave links may be significantly impaired.Key words: radio refractivity, surface duct, penetration angle, refractivity gradient

Reliability of cut mark analysis in human costal cartilage: The effects of blade penetration angle and intra- and inter-individual differences

Identification of tool class characteristics from cut marks in either bone or cartilage is a valuable source of data for the forensic scientist. Various animal models have been used in experimental studies for the analysis of individual and class characteristics. However, human tissue has seldom been used and it is likely to differ from that of non-humans in key aspects. This study wishes to assess how the knife's blade angle, and both intra- and inter-individual variation in cartilage samples affect the ability of costal cartilage to retain the original class characteristics of the knife, as measured microscopically by the distance between consecutive striations. The 120 cartilaginous samples used in this study originated from the ribcage of 6 male cadavers which were submitted to autopsy at the North Branch of the National Institute of Legal Medicine, in Portugal. Three different serrated knives were purchased from a large department store, and were used in the experimental cuts. Samples of costal cartilage from 2 individuals were assigned to each knife. Each individual provided 20 cartilage samples. Cartilage samples were manually cut using each of the three knives, following two motions: one straight up-and-down cutting motion and parallel and one perpendicular to the blade's teeth long axis forward cutting motion. Casts of the samples were made with Mikrosil®. Image capture and processing were performed with an Olympus stereomicroscope and its software. The blade's penetration angle and inter-individual variation were shown to affect the identification of the tool class characteristics from the striation pattern observed in a kerf wall, although this seems to be related only to the degree of calcification of the costal cartilage. Intra-individual variation does not seem to significantly affect the identification of the tool class characteristics from the striation pattern observed in a kerf wall, for the same knife following the same motion. Although this study did not quantify the degree of calcification of the cartilage, this seems to be an important source of great variation regarding the interpretation of striation pattern in cartilage.

Characteristics of compressed natural gas jet and jet-wall impingement using the Schlieren imaging technique

An experimental study was performed to investigate the compressed natural gas jet characteristics and jet-wall impingement using the Schlieren imaging technique and image processing. An injector driver was used to drive the natural gas injector and synchronized with camera triggering. A constant-volume optical chamber was designed to facilitate maximum optical access for the study of the jet macroscopic characteristics and jet-wall impingement at different injection pressures and injectors-wall distances. Measurement of the jet tip penetration and cone angle at different conditions are presented in this paper together with temporal presentation of the jet radial travel along the wall.

Controlling wettability and hydrophobicity of organoclays modified with quaternary ammonium surfactants

The montmorillonite clays were modified with quaternary ammonium salts (QASs) having different alkyl chain lengths and a benzyl substitute group. The modified organoclays were characterized by different analytical techniques. The wettability and hydrophilicity/hydrophobicity of the modified clays was evaluated using water or oil penetration (adsorption) and contact angle measurements. The loading of QASs was in the range of 0.60–0.75mmol/g per clay, irrespective of the type of QAS used for the modification of the clay. From the analytical investigations, it was elucidated that the modification of clay with QAS affected the structural, textural, and surface properties. Moreover, it should be noted that the modification with QAS having benzyl substitute group resulted in water-non-wettable and superhydrophobic surface, whereas clays modified with QAS without benzyl substitute group became more water-wettable and hydrophilic than the pristine clay. The presence of benzyl groups on the clay prevents water from penetration into the inter-clay or interlayer spacing, which yields the hydrophobic surface. These behaviors can arise from molecular arrangement of QAS on clay but not be attributable to the amount of QASs, and the surface area, size, and zeta potential of particles.

Production and installation study of the ITER PF4 in-pit feeder

The PF4 in-pit feeder includes the In-Cryostat-Feeder (ICF) and Cryostat-Feed-Through (CFT), with busbars being their key components. The relative positions of the busbar terminal joints are measured by using a laser tracker and adjusted by positioning tools. The busbars are not fixed on the separate plate until the position errors meet the manufacture tolerances. The CFT has a 2.38° penetration angle relative to the ground and will be installed firstly. The position of the connection interface between the CFT and its lifting tool is analyzed, and to reduce the total deformation and keep the assembly precision of the joints the straight part of the CFT needs to be supported. The ICF has the most critical assembly operation space, as it must be installed on its temporary support in a temporary position. After the PF4 coil has been installed the ICF will be moved to its final position. To guarantee the 30mm safety assembly clearance provided by ITER, the collision analysis of the ICF is performed, which demonstrates that the assembly procedures are feasible.

바이오연료의 디젤엔진 적용에 관한 실험연구

Compared to gasoline engines, diesel engines with a relatively simple ignition system are more advantageous in the application of biodeisel fuel to engine. Then in this study the comparative analysis on the spray characteristics and combustion emissions characteristic between the biodiesel(soybean oil) and diesel, the fuel for commercial diesel engine, was performed with common rail injection system. Injection pressure and ratio of biodiesel blended fuel were selected as main experimental variables. Consequently, it can be found that there is no significant difference in the macro characteristics of the spray behavior(spray penetration and spray angle) in response to change in the blend ratio of soybean oil and diesel at a fixed injection pressure, in particular, soot creation in combustion emissions in the region of low pressure was greatly affected by the blend ratio of soybean oil, however, the creation in the region of high pressure was almost unaffected by the blend ratio because of promoted atomization.

A methodology for laser diagnostics in large-bore marine two-stroke diesel engines

Large two-stroke diesel engines for marine propulsion offer several challenges to successful implementation of the laser diagnostic techniques applied extensively in smaller automotive engines. For this purpose a fully operational large-bore engine has been modified to allow flexible optical access, through 24 optical ports with clear diameters of 40 mm. By mounting the entire optical set-up directly to the engine, effects of the vigorous vibrations and thermal drifts on alignment can be minimized. Wide-angle observation and illumination, as well as relatively large aperture detection, is made possible through mounting of optical modules and relays inside optical ports. This allows positioning of the last optical element within 10 mm from the cylinder wall. Finally, the implementation on a multi-cylinder engine allows for flexible and independent operation of the optically accessible cylinder for testing purposes. The performance of the integrated optical engine and imaging system developed is demonstrated through laser Mie scattering imaging of fuel jet structures, from which information on liquid penetration and spray angles can be deduced. Double pulse laser-sheet imaging of native in-cylinder structures is also demonstrated, for the purpose of velocimetry.