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The purpose of this paper is to simplify the testing of coolants for grinding in the automotive industry.

A simple equipment is developed to test the coolant, by simulating the coolant‐grinding wheel‐workpiece interface and measuring in terms of grinding parameters.

It was found that the simulator could indicate the performance trends that closely match the actual grinding conditions.

Since this is a general system, it has to be customised with individual settings of the machining parameters for a meaningful interpretation and for comparison between machines.

This equipment will simplify the selection of coolants for grinding and serve as a pre‐qualifier before approving for trials in full‐scale shopfloor conditions.

The design of the equipment is new and provides an alternate for the otherwise costly, full‐scale evaluation of coolants on the shopfloor.

The purpose of this study is to explore the mist-air film cooling performance on a three-dimensional (3-D) flat plate. In mist-air film cooling technique, a small amount of water droplets is injected along with the coolant air. The objective is to study the influence of shape of the coolant hole and operating conditions on the cooling effectiveness.

In this study, 3-D numerical simulations are performed. To simulate the mist-air film cooling over a flat plate, air is considered as a continuous phase and mist is considered as a discrete phase. Turbulence in the flow is accounted using Reynolds averaged Navier–Stokes equation and is modeled using k–e model with enhanced wall treatment.

The results of this study show that, for cylindrical coolant hole, coolant with 5% mist concentration is not effective for mainstream temperatures above 600 K, whereas for fan-shaped hole, even 2% mist concentration has shown significant impact on cooling effectiveness for temperatures up to 1,000 K. For given mist-air coolant flow conditions, different trend in effectiveness is observed for cylindrical and fan-shaped coolant hole with respect to main stream temperature.

This study is limited to a flat plate geometry with single coolant hole.

The motivation of this study comes from the requirement of high efficiency cooling techniques for cooling of gas turbine blades. This study aims to study the performance of mist-air film cooling at different geometric and operating conditions.

The originality of this study lies in studying the effect of parameters such as mist concentration, droplet size and blowing ratio on cooling performance, particularly at high mainstream temperatures. In addition, a systematic performance comparison is presented between the cylindrical and fan-shaped cooling hole geometries.

Endwall film cooling protects vane endwall by coolant coverage, especially at the leading edge (LE) region and vane-pressure side (PS) junction region. Strong flow impingement and complex vortexaa structures on the vane endwall cause difficulties for coolant flows to cover properly. This work aims at a full-scale arrangement of film cooling holes on the endwall which improves coolant efficiency in the LE region and vane-PS junction region.

The endwall film holes are grouped in four-holes constructal patterns. Three ways of arranging the groups are studied: based on the pressure field, the streamlines or the heat transfer field. The computational analysis is done with the k-ω SST model after validating the turbulence model properly.

By clustering the film cooling holes in four-holes patterns, the ejection of the coolant flow is stronger. The four-holes constructal patterns also improve the local coolant coverage in the “tough” regions, such as the junction region of the PS and the endwall. The arrangement based on streamlines distribution can effectively improve the coolant coverage and the arrangement based on the heat transfer distribution (HTD) has benefits by reducing high-temperature regions on the endwall.

A full-scale endwall film cooling design is presented considering interactions of different film cooling holes. A comprehensive model validation and mesh independence study are provided. The cooling holes pattern on the endwall is designed as four-holes constructal patterns combined with several arrangement choices, i.e. by pressure, by heat transfer and by streamline distributions.

The purpose of this paper is to investigate and contribute to a better understanding of cutting process characteristics using the proposed RBD Palm Olein-based organic mixed coolant.

In this research, refined, bleached and deodorized (RBD) Palm Olein is selected as the base oil for organic coolant and mixed coolant (base oil mixed with chemicals) to compare with the cutting performance of industrial water-soluble chemical (inorganic) coolant. Using coated carbide tool, JIS SS400 Mild Steel was tested in milling process. At fixed spindle speed, the relations between feed rate and depth of cut (DOC) on cutting temperature and surface roughness were investigated. Also, the dynamic viscosity, specific heat capacity and pH level for each coolant are taken into consideration.

As predicted, cutting fluid with lower viscosity removes more heat. The cutting temperature increased with increasing feed rate and DOC. However, surface roughness increased with increasing feed rate but decreased with increasing DOC. From the data gathered, the proposed RBD Palm Olein-based organic mixed coolant showed better heat removal properties than organic coolant and it produced a far better machined surface than inorganic coolant.

Overall, the proposed organic mixed coolant has shown great potential to be a good cutting fluid when balance between cooling properties and lubricity, and consistent quality of cutting fluids are sought to produce environmental friendly quality workpiece.

This paper aims to investigate the film cooling effectiveness (FCE) and mixing flow characteristics of the flat surface ramp model integrated with a compound angled film cooling jet.

Three-dimensional numerical simulation is performed on a flat surface ramp model with Reynolds Averaged Navier-Stokes approach using a finite volume solver. The tested model has a fixed ramp angle of 24° and a ramp width of two times the diameter of the film cooling hole. The coolant air is injected at 30° along the freestream direction. Three different film hole compound angles oriented to freestream direction at 0°, 90° and 180° were investigated for their performance on-ramp film cooling. The tested blowing ratios (BRs) are in the range of 0.9–2.0.

The film hole oriented at a compound angle of 180° has improved the area-averaged FCE on the ramp test surface by 86.74% at a mid-BR of 1.4% and 318.75% at higher BRs of 2.0. The 180° film hole compound angle has also produced higher local and spanwise averaged FCE on the ramp test surface.

According to the authors’ knowledge, this study is the first of its kind to investigate the ramp film cooling with a compound angle film cooling hole. The improved ramp model with a 180° film hole compound angle can be effectively applied for the end-wall surfaces of gas turbine film cooling.

This study aims to introduce a three-hole cooling unit to improve downstream cooling performance by jet interaction and coalescence at a lower manufacture cost.

A new three-hole cooling unit is proposed. Reynolds-averaged Navier–Stokes (RANS) simulation is performed in the present study. The CFD package ANSYS CFX is used to predict film-cooling effectiveness and flow fields.

The results show that, at pitch ratio P/D = 3, Case 4 configuration with a round hole upstream and two trenched holes downstream can obtain a high cooling performance at a lower manufacture cost, especially at the higher turbulence. Considering the effect of increased pitch ratio, Case 6 configurations of three staggered trenched holes show a superior downstream cooling performance than Case 4 configurations. Case 6 configurations have the potential of achieving a high cooling performance with a reduced number of holes and less coolant flow.

The application of these cooling units in the turbine passage will be conducted in the future. The more detailed flow field will be simulated by large eddy simulation in the following research.

The round and trenched cooling holes have been proved to be achievable in the manufacture. This combined three-hole cooling unit will give the opportunity to increase turbine inlet temperature further.

Both cooling performance and practical manufacture are taken into account. This cooling scheme will give a superior surface protection on the hot components.

The purpose of this paper is to investigate the effects of liquid carbon dioxide (LCO₂) on grinding of stainless steel.

A factorial experimental approach was used to compare the LCO₂'s performance against grinding under dry air and emulsion coolants.

The experimental results have a great use to practitioners. It was found that under special conditions, LCO₂ proves to be an alternative coolant for grinding of temperature sensitive materials. Furthermore, grinding under LCO₂ conditions produced the lowest tangential force, while the normal forces were close to the values found under emulsion fluid environment. When compared to grinding under dry conditions, LCO₂ coolant was successful in reducing the work piece temperatures. LCO₂ and emulsion conditions inhibit work hardening by reducing material deformation at the grinding zone.

The paper shows that sub‐zero temperature coolants have the ability to bring about lower grinding temperatures than what is typically achieved under conventional fluids.

The purpose of this paper is to report the result of a numerical investigation of film cooling performance on a flat plate for finding optimum blowing ratios.

Steady-state simulations have been performed, and the flow has been considered incompressible. Calculations have been performed with 3D finite-volume method and the k-e turbulence model.

The adiabatic film cooling effectiveness and the effects of density ratio (DR), blowing ratio (M) and main stream turbulence intensity (Tu), coolant penetration, hole incline and diameter are studied. The temperature and film cooling effectiveness contours, centerline and laterally film cooling effectiveness are presented for these cases. Results show that the cases with smaller Tu have better effectiveness. In the console, using the air coolant and in cylindrical hole cases, using CO₂ coolant fluid has higher effectiveness. The results indicated that there is an optimum blowing ratio in the cylindrical hole cases to optimize the performance of new gas turbines.

Investigation of optimum blowing ratio for the convex surfaces and turbine blades is a prospective topic for future studies.

The motivation of this study comes from several industrial applications such as film cooling of gas turbine components. This research gives the best blowing ratio for receiving maximum cooling effectiveness with minimum coolant velocity.

This study optimizes the blowing ratio for film cooling on a flat plate.

The purpose of this paper is to develop water vapour as a new cooling and lubricating technique in drilling Ti6Al4V. Water vapor is an economical and eco‐friendly coolant and lubricant. However, it is necessary to study the drilling chip deformation, forces and drilling temperature when drilling Ti6Al4V using this new green drilling technology, which meets the development trend of green machining technology.

Comparative experiments are carried out with HSS drill bits and YG6X (K10 type in ISO) cemented carbide drill bits in drilling Ti6Al4V under the conditions of oil water emulsion, water vapor as coolant and lubricant and dry drilling, respectively. The drilling forces, temperature and drill bit wear VBmax have been examined and analyzed. Further, a new type practical drilling quick‐stop device is developed for studying the chip deformation in drilling Ti6Al4V. The drilling forces distribution test in drilling Ti6Al4V is also developed.

When water vapor is used as coolant and lubricant, the torque is reduced by 15‐25%, 5‐10% in comparison with dry drilling and oil water emulsion, respectively; the thrust is reduced by 5‐10%, 4‐5%; the temperature is reduced by 15‐20%, 5‐8% and the wear VBmax of drill bit is reduced by 60‐80%, 10‐15%, correspondingly. Also, the contact length in chip‐tool interface decreases and the drilling deformation is reduced. The coolant and lubricant conditions and feed rate have little impact on the drilling force distribution in drill bit cutting edges.

A green machining technology, water vapor used as coolant and lubricant, is used in drilling Ti6Al4V; it can reduce drilling deformation, drilling forces, temperature and flank wear. A new drilling quick‐stop device is devised to obtain the drilling chip roots. Also, the drilling force distribution test was developed for obtaining the rate of drilling forces in cutting edges when drilling Ti6Al4V.

Subcooled flow boiling phenomenon is characterized by coolant phase change in the vicinity of the heated wall. Although coolant phase change from liquid to vapour phase significantly enhances the heat transfer coefficient due to latent heat of vaporization, eventually the formed vapor bubbles may coalesce and deteriorate the heat transfer from the heated wall to the liquid phase. Due to the poor heat transfer characteristics of the vapour phase, the heat transfer rate drastically reduces when it reaches a specific value of wall heat flux. Such a threshold value is identified as critical heat flux (CHF), and the phenomenon is known as departure from nucleate boiling (DNB). An accurate prediction of CHF and its location is critical to the safe operation of nuclear reactors. Therefore, the present study aims at the prediction of DNB type CHF in a hexagonal sub-assembly.

Computational fluid dynamics (CFD) simulations are performed to predict DNB in a hexagonal sub-assembly. The methodology uses an Eulerian–Eulerian multiphase flow (EEMF) model in conjunction with multiple size group (MuSiG) model. The breakup and coalescence of vapour bubbles are accounted using a population balance approach.

Bubble departure diameter parameters in EEMF framework are recalibrated to simulate the near atmospheric pressure conditions. The predictions from the modified correlation for bubble departure diameter are found to be in good agreement against the experimental data. The simulations are further extended to investigate the influence of blockage (b) on DNB type CHF at low operating pressure conditions. Larger size vapour bubbles are observed to move away from the corner sub-channel region due to the presence of blockage. Corner sub-channels were found to be more prone to experience DNB type CHF compared to the interior and edge sub-channels.

An accurate prediction of CHF and its location is critical to the safe operation of nuclear reactors. Moreover, a wide spectrum of heat transfer equipment of engineering interest will be benefited by an accurate prediction of wall characteristics using breakup and coalescence-based models as described in the present study.

Simulations are performed to predict DNB type CHF. The EEMF and wall heat flux partition model framework coupled with the MuSiG model is novel, and a detailed variation of the coolant velocity, temperature and vapour volume fraction in a hexagonal sub-assembly was obtained. The present CFD model framework was observed to predict the onset of vapour volume fraction and DNB type CHF. Simulations are further extended to predict CHF in a hexagonal sub-assembly under the influence of blockage. For all the values of blockage, the vapour volume fraction is found to be higher in the corner region, and thus the corner sub-channel experiences CHF. Although DNB type CHF is observed in corner sub-channel, it is noticed that the presence of blockage in the interior sub-channel promotes the coolant mixing and results in higher values of CHF in the corner sub-channel.