Exit Profiles Research Articles

Influence of Dilution and Effusion Flows in Generating Variable Inlet Profiles for a High-Pressure Turbine

Abstract The elevated flow temperatures and pressures exiting gas turbine combustors affect the efficiency and durability of the high-pressure turbine stage. Understanding the effects that result from the upstream dilution and effusion flow interaction in creating the combustor exit profiles is important to advancing gas turbines. Understanding how common combustor features, such as dilution jets and effusion cooling, interact based on computational predictions guided the design of a non-reacting profile simulator capable of producing a wide range of non-uniform temperature profiles representative of those entering high-pressure turbines. The mechanical design of a new simulator device, which will be experimentally tested in the future, is presented in this paper along with computational predictions of flow and thermal fields. The simulator was designed for modular installation into the Steady Thermal Aero Research Turbine (START), which is a continuous-duration, steady-state turbine facility that houses a single-stage test turbine. Features of the simulator included interchangeable liner panels with multiple rows of dilution jets and wall effusion cooling to study various hole diameters and patterns. The dilution jets generate elevated turbulence intensities and tailor the temperature profiles in the radial and circumferential directions. The air mass flow distribution and source flow temperatures are independently controlled. To aid in the simulator design, computational fluid dynamics (CFD) simulations using Reynolds-averaged Navier–Stokes modeling were conducted with a two-level Design of Experiments (DOE) approach to determine a number of engine-representative target profiles with temperature shapes that are mid-radius peaked, outer-diameter peaked, inner-diameter peaked, and uniform. A sensitivity analysis of the CFD DOE results determined which factors significantly affected the profile shape so that the target profiles could be produced. The analysis indicated that the main contributor to the temperature profile shape at near-wall vane radial span locations of 0–15% and 85–100% was the injection temperature of the effusion flow. The main contributor at radial span locations of 15–40% and 60–85% was the injection temperature of the third-row dilution jets, and at the mid-radius location of 40–60% vane radial span, the main contributor was the diameter of the first-row dilution holes.

Prediction and control of profile for silicon steel strip in the whole tandem cold rolling based on PSO-BP algorithm

In the rolling process of silicon steel strip of the five-stand UCMW tandem cold rolling line, the quality of finished profile is the result of cooperative control of five stands, the exit profiles of the first four stands jointly decide the exit profile of the fifth stand, so it is necessary to accurately control the strip profile in the rolling process. However, the shapemeter is only typically equipped at the exit of fifth stand, making it impossible to obtain the strip profile of the first four stands. A profile prediction model for the whole tandem cold rolling based on PSO-BP algorithm is established, compared with the finite element method, this model can satisfy the demand for fast prediction of strip profile and quickly analyzing the profile change characteristics for five stands according to the adjustment of profile control parameters in the industrial field. Firstly, a 3D elastic-plastic finite element model of rolls and strip for five stands is built, and a large number of profile calculation data are as the training sample sets to build the PSO-BP model. Through the transfer calculation of strip profile between adjacent stands, the PSO-BP model of five stands is established, and the validity is verified by comparing with the actual measured data. Secondly, to improve the quality of product profile, focusing on the unreasonable setting of production parameters, many improvement schemes of WRB and WRS for five stands are designed, and the PSO-BP model is used to quickly calculate the strip profile, then comparing the result of each scheme, the optimum improvement scheme is selected, which is furtherly carried out rolling experiments in the industrial field, and the quality of strip profile is well improved. At present, the new scheme has been successfully applied to industrial production.

Femtosecond laser drilling 100 μm diameter micro holes with aspect ratios > 20 in a Nickel based superalloy

Micro holes with high aspect ratios are essential for the cooling performance of aero-engines. Challenges persist in deep hole drilling due to the escalating stringent requirements in terms of hole diameters, aspect ratios, and 3D profiles. In this study, we propose a two-step femtosecond laser drilling method to produce cylindrical micro holes with diameters of ∼100 μm, aspect ratios >20, and near-zero taper angle in Inconel 718 plates. In the first drilling period, the laser polarization trepanning method is used, yielding through-holes with aspect ratios >20 but undesired tapers and irregular shapes at the hole exit. A new method called laser spinning is then introduced in the second drilling period, proficiently decreasing taper angles to be < 0.05° and improving the irregular exit profiles into circular contours. Employing a rotating inclined laser beam, the laser spinning method facilitates deep hole drilling by enhancing laser penetration, solely resulting augmented hole diameters at the exit without compromising hole aspect ratios. The efficacy of this drilling approach is achieved through modifying the incident laser reflection on internal hole walls. Overall, the presented results and analyses hold great promise for high-quality deep hole drilling in opaque materials, particularly for products regarding aero-engines.

Demo Lessons and Peer Observation to Enhance Student Teachers’ Competencies and Exit Profiles

Demo Lessons and Peer Observation to Enhance Student Teachers’ Competencies and Exit Profiles

A Turbo-Oriented Data-Driven Modification to the Spalart–Allmaras Turbulence Model

Abstract The Spalart–Allmaras (SA) turbulence model is one of the most popular models applied to compressors, but it often over-predicts blockage size and hence under-predicts the stall margin. In this paper, a novel modification to the SA model is proposed to improve the prediction of compressor near-stall flows. The modification is based on the dimensionless vortical pressure gradient, which identifies blockage cells featured by 3D swirling, adverse pressure gradient, and low-momentum flows. It unblocks the compressor passage by enhancing the eddy viscosity in the identified blockage cells; whereas in canonical 2D flows the modification is automatically switched off. The model coefficients are calibrated via Bayesian inference, which considers the uncertainties involved in experiments and computational fluid dynamics (CFD) simulations of turbomachinery. The rotor exit radial profile data of NASA Rotor 67 at peak-efficiency and near-stall points are used for calibration. The calibrated model is tested extensively in four compressors covering both tip blockage and corner separation as well as both industrial and laboratory Reynolds number and Mach number. For the NASA Rotor 67 and the TUDa-GLR-OpenStage, the proposed model predicts more accurate stall margins at all operating speeds due to the tip unblocking effect. For the BUAA Stage B rotor, the proposed model predicts the tip blockage size and thus the stall margin more accurately. For the LMFA NACA65 cascade, the proposed model with the quadratic constitutive relation (QCR) achieves significant improvement in predicting the exit profiles due to the unblocking effect on the corner separation. The proposed model, termed as SA-PGω in this work, is a promising engineering tool for future Reynolds-averaged Navier–Stokes (RANS) simulations of compressor near-stall flows.

Análisis documental de los perfiles de egreso vigentes de las carreras de Fisioterapia en Chile

IntroductionThe entry-level profile corresponds to a formal statement of an institution about the intended learning outcomes of a profession. This commitment includes developing a professional identity, specifying the main areas of professional activity and its key attributes. Besides, universities’ training must transparentize institutions’ commitments to their graduates and society. There is currently no standard for professional training in Physiotherapy in Chile, and it is necessary to move toward this purpose by starting with an analysis of what universities offer today. PurposeTo analyze the main areas of performance and competencies declared in the competency-based exit profile of Physiotherapy entry-level programs delivered in 2021 in Chile. Material and methodQualitative documentary research was carried out of the competency-based exit profile, published on the web sites of 41 Higher Education institutions in Chile that delivered Physiotherapy entry-level University Programs during the 2021. A thematic content analysis was carried out assisted by CAQDAS NVivo 12 pro. ResultsSeven main categories were obtained that characterize competence areas of the current competency-based exit profile in Physiotherapy entry-level programs in Chile: physiotherapist intervention; clinical reasoning in physiotherapy; promotion and prevention in health; research; health management and administration; education; and entrepreneurship and innovation. ConclusionsThe main areas of performance present in the exit profiles of the university programs of Physiotherapy in Chile were identified. A reflection would be made about the practical meanings for university professional training in Physiotherapy in Chile to respond to the present and future professionals requirements with the identity centered on the human movement as the axis of professional action.

Towards competence-oriented higher education: a systematic literature review of the different perspectives on successful exit profiles

PurposeThe twenty-first century education system seeks to meet the societal demands of economic effectiveness and the unique professional development needs of individuals. This paper aims to discuss the qualities of competence-oriented educational processes and the recent movement towards competence-based curricula in higher education.Design/methodology/approachThis study follows a systematic literature review (SLR) methodology to explore the concept of competence within the context of educational science. The subsequent thematic synthesis analyses the findings of reviewed publications regarding graduate attributes in competence-oriented higher education and their perspectives and working-life expectations on exit profiles.FindingsInterest in competence-oriented education, training and learning has grown in recent years, resulting in numerous theoretical and technical pedagogical applications in higher education. Nonetheless, ambiguous terminology presents a significant challenge, which is demonstrated by the inconsistent language of the study's results. Moreover, there is an obvious need for teachers' in-service training. The qualitative synthesis of this article will be useful for both educational and working life sectors to inform and promote different perspectives on competence-oriented educational processes. A clear articulation of competences is crucial for reforming higher education to meet students' interests and recognise their work-life needs.Originality/valueThe concept of competence has been under-investigated in higher education research and practices. This study offers novel insights and practical implications for competence-oriented learning concerning the paradigmatic change across higher education.

Development of an Inverse Plume Model for Mass Eruption Rate in Unsteady Conditions

Abstract Following volcanic eruptions, forecasters need accurate estimates of mass eruption rate (MER) to appropriately predict the downstream effects. Most analyses use simple correlations or models based on large eruptions at steady conditions, even though many volcanoes feature significant unsteadiness. To address this, a superposition model is developed based on a technique used for spray injection applications, which predicts plume height as a function of the time-varying exit velocity. This model can be inverted, providing estimates of MER using field observations of a plume. The model parameters are optimized using laboratory data for plumes with physically relevant exit profiles and Reynolds numbers, resulting in predictions that agree to within 10% of measured exit velocities. The model performance is examined using historic eruptions with well-documented unsteadiness, again providing MER estimates of the correct order of magnitude. This method can provide a rapid alternative for real-time forecasting of small, unsteady eruptions.

Design, Testing, and Performance Impact of Exhaust Diffusers in Aero-Derivative Gas Turbines for Mechanical Drive Applications

Abstract The growing penetration of renewables calls for power generation and mechanical drive gas turbine (GT) capable of quickly adjusting production and operate at part load. Aero-derivative engine architectures leverage the large experience from aircraft propulsion, have small footprint, high performance, availability, and maintainability. Aircraft engines adjust power with fuel rate and shaft speed that go hand in hand. Mechanical drive engines need to change the delivered power by keeping the shaft speed under control to guarantee the operation of the driven equipment (an LNG compressor or an electric generator). Hence, the power turbine exhaust may deliver velocity and angle profiles that put the discharge diffuser in severe off-design with flow separations, high kinetic losses, and cycle performance shortfall. This paper describes Baker Hughes a GE company experience in the computational fluid dynamics (CFD) assisted design and similitude scale-down testing of aero-derivative hot-end drive exhaust diffusers in multiple operating points. The diffuser inlet conditions reproduce power turbine exit profiles by using swirl vanes and perforated plates, the design of which is heavily CFD assisted. Predictions match measurements in terms of pressure recovery, kinetic losses, and exhaust velocity profiles. Different data postprocessing and averaging are considered to properly factor in the diffuser losses into the overall turbine performance.

Time-resolved particle image velocimetry measurements of a tandem jet array in a crossflow at low velocity ratios

Investigation of the near field dynamics of a single and tandem array of three jets are provided by 2-D time-resolved particle image velocimetry (TR-PIV) measurements. Instantaneous velocity fields are examined in the transverse and spanwise planes with jet to crossflow velocity ratios in the range from 0.9 to 1.7. Previous studies have shown that for high ratios (\(\ge\) 2), the leading jet provides sufficient shielding to ensure that all jets downstream exhibit nearly identical flow characteristics. The current transverse plane measurements exhibit more unique and localized features as a result of the competing effects of pressure gradients and vortex mechanisms assessed via the jet exit profiles, first and second order turbulent statistics, streamline trajectories, recirculation areas and penetrations depths. Proper orthogonal decomposition (POD) is applied to the spanwise plane instantaneous velocity fields to determine the statistically dominant features of the single and tandem jet configurations at equivalent velocity ratios. The velocity fields are then reconstructed using the truncated POD modes to provide further insight into the shear layer and wake vortices that drive these configurations. Vortex identification algorithms are applied to the reconstructed velocity fields to determine the statistical characteristics of the vortices, including their centroids, populations, areas and strengths, each of which exhibit largely different dependencies on jet configuration and velocity ratio. Several of the investigated metrics are found to exhibit different behaviors below and above a velocity ratio of unity and also as a function of increasing velocity ratio between 1 and 2, implying that several transitions mechanisms are present in the low velocity ratio regime investigated herein.Graphic abstract

Formación de recursos humanos para la atención primaria de la salud basada en actividades profesionales confiables

&lt;p&gt;La formación de recursos humanos para la salud (rhs) es una tarea conjunta de las instituciones educativas y de salud, para ello se requiere establecer los perfiles laborales, profesionales y de egreso de cada rhs. Como parte del desarrollo de la educación basada en competencias (ebc) se crearon las Entrustable Professional Activities (epa) naturalizadas en México como Actividades Profesionales Confiables (aproc), estas permiten operacionalizar las competencias y hacer más efectiva su implementación. En este artículo se presenta la propuesta de seis aproc generales, para la formación de rhs que pueden desarrollarse de manera gradual para que, al egreso, sean capaces de practicarlas de forma integral y confiable, también son interprofesionales y útiles para cualquier disciplina de la salud. La propuesta integra el proceso salud-enfermedad, la salud universal y la atención primaria de salud. Al utilizar las aproc generales como marco formativo, se podrían proponer acuerdos y prácticas intersectoriales e interdisciplinarias, esto implica un paso más allá de la ebc y plantea un cambio en el paradigma educativo que transformará la atención primaria de la salud (aps) de acuerdo con las metas regionales y las necesidades nacionales.&lt;/p&gt;

A study on geometrical features of electric discharge machined channels on AA6061-4%B4C composites

The aluminum alloy AA6061-4wt.% boron carbide (B4C) particulate metal matrix composites were fabricated by the stir casting method. The die-sinker electric discharge machining was performed to make the rectangular mini channels on these composites. The full factorial experimental design that consists of three input conditions, the current ( I), discharge duration ( T-on), and discharge idle time ( T-off) at three levels each (33 = 27 total runs), was used for experimentation. The volume, V, the taper, θ (along with the depth), the lateral overcut (along the width), and the difference in depth, Δ d (between total depth and depth up to the tapered profile) at entrance and exit cross-sectional profiles of the channel were considered as output responses. The θ, lateral overcut, and Δ d were calculated from the entrance and exit profiles which were obtained by extracting the data points of each channel with the help of an optical profile projector. The computer-aided geometric model was developed to estimate the volume. A set of optimum electric discharge machining parameter levels were identified for maximum V and a minimum of θ, lateral overcut, and Δ d. Analysis of variance was performed to identify the significant parameter and the contribution toward output responses. Results showed that the volume was found to be maximum at higher I (8 A) and lower T-On (25 µs) conditions. The taper was found to decrease with the increase in current but both lateral overcut and Δ d increased. Both I and T-On are found to be the significant parameters affecting both V and Δ d, whereas current is for θ and lateral overcut. In some cases, it was observed that there is a considerable difference in the θ and the lateral overcut values in the entrance and exit portions for the same channel. It is because of the randomly dispersed B4C particles which alter the material removal mechanism.

Graduation Profiles of Pedagogy Programmes According to the Current Educational Policies

The research analyzes the graduate profiles of pedagogical careers belonging to the universities of the Valparaíso region, Chile. For this purpose, a metrically consistent instrument has been proposed and created, according to the main Education Policies of the country that is called as an integral profile, which includes aspects with which Chilean teachers are evaluated, plus indicators of inclusion and citizen education. These Policies are not always measured, that’s why universities give such importance to these three educational policies. For these reasons, the objective of this article is to analyze, based on quantitative techniques, the relation of similarity between graduation profiles and educational policies, contributing to empower the descended aspects and to visualize the importance that the universities grant to train students with an integral profile. The results of this research invite to promote the Educational Policies related to the exit profiles of the pedagogical careers, since having integral profiles contributes to form a model of teacher training for the country, especially in those with emerging economies, such as those of Latin America.

Kilovoltage transit and exit dosimetry for a small animal image-guided radiotherapy system using built-in EPID.

We investigated the potential use of the built-in electronic portal imaging device (EPID) in the small animal radiation research platform (SARRP) as a dosimeter in the kV energy range. To this end, we developed a method for converting portal images to a two-dimensional (2D) dose maps at the detector plane and object's exit surface and validated them against empirical dose measurements. We calibrated the SARRP's EPID to measure transit dose. The transit dose map was back-projected to calculate 2D dose distribution at the object's exit surface. The accuracy of transit and exit dose distributions was independently validated with a PinPoint ion chamber (IC) and Gafchromic EBT3 film measurements for a range of radiation dose rates (0.43-2.78 cGy/s), cone sizes (5-40 mm), in a homogeneous phantom of varying thickness (0-50 mm) and in an inhomogeneous phantom containing graphite, cork, air, and aluminum. In-air central axis (CAX) transit dose values measured with the EPID showed close agreement with film and IC measurements. The maximum differences in EPID in-air transit measurements with film or IC measurements were 1%. The EPID was capable of accurately measuring phantom transit dose independently of the attenuating phantom thickness, with average discrepancies of 0.5% and 2.9% with IC and film, respectively, where the maximum difference between the EPID and the IC was 1.8%. The results were slightly worse for film, with maximum differences in 4.9%. Output factor measurements using EPID were within 2.9% of both IC and film measurements. In addition, calculated exit doses agreed with film values within ≤3.1%, for attenuating phantom thicknesses ≥15 mm. The agreement became worse with decreasing phantom thickness; for thicknesses of 10 and 5 mm, agreements were ≤5.7% and ≤6.9%, respectively. Compared to film, transit and exit profiles measured with the EPID showed average differences <2% for both homogeneous and inhomogeneous materials. We developed and validated a novel 2D transit/exit dosimetry for a kV SA-IGRT system using an EPID. We verified the accuracy of our method to measure EPID transit and exit dose distributions for a range of dose rates, beam attenuation, and collimation. Our results indicate that the EPID can be used as a simple, convenient device for kV dose delivery verification in small animal radiotherapy.

Combined experimental and numerical study of ethanol laminar flame extinction

ABSTRACTExtinction strain rates of ethanol at atmospheric pressure were investigated in laminar counter-flow diffusion flames as a function of nitrogen dilution through both experiment and two-dimensional axisymmetric full domain numerical analysis. An opposed-jet burner configuration with straight-tube fuel and air nozzles and having two different design nozzle exit flow profiles was used in the experiments. An advanced numerical solution algorithm, which makes use of a block-based parallel implicit finite-volume scheme, was used to obtain the corresponding simulation results. A comparison of the numerical results for two different chemical kinetic mechanisms helped to identify key factors affecting the flame extinction. While the predicted values over estimated the experimentally observed global strain rate extinction limits, the general trends and nozzle flow profiles were well captured. The local strain rates near extinction were also examined numerically and shown to be independent of the nozzle velocity flow profile and a fundamental property of the reactants. The experimental data from the present study were also compared to previous measurements and good agreement was demonstrated. The predicted nozzle exit and axial velocity flow profiles arising from the two-dimensional analysis were examined and limitations of conventional one-dimensional counter-flow analyses were highlighted.

La importancia de la contabilidad electrónica en el currículum

&lt;p&gt;El presente artículo habla sobre la contabilidad electrónica en el sistema tributario de México. Esto es importante para los contribuyentes a partir de 2014, porque obliga a las personas físicas y morales del país a llevar el registro de la contabilidad en medios electrónicos y su envío periódico a través del buzón tributario del Servicio de Administración Tributaria (SAT). El objetivo de este artículo es argumentar la necesidad de incluir la contabilidad electrónica en el currículum de la Licenciatura en Contaduría Pública, al considerar que los perfiles de egreso de la mayoría de las universidades, aún siguen el desarrollo de las competencias tecnológicas que exigen hoy en día las obligaciones tributarias.&lt;/p&gt;&lt;p&gt;Realidad y Reflexión Año 17, No 45, Enero-Junio 2017: 8-16&lt;/p&gt;

Two-dimensional effects in counterflow methane flames

The effect of flowfield geometry on flame propagation and extinction of atmospheric CH4/N2/air flames was studied in the counterflow configuration. Laminar flame speeds and extinction strain rates for lean premixed and non-premixed flames were measured in axisymmetric burners producing either uniform or non-uniform axial velocity exit profiles. Particle image velocimetry was used to characterize the two-dimensional flowfield between the burners. The experiments were modeled with a one-dimensional code and a detailed C2 hydrocarbon kinetic model. Laminar flame speeds were found to be insensitive to the burner exit velocity profile shape but extinction measurements were strongly affected. In non-uniform flows, two-dimensional flow field measurements revealed significant radial dependence of flow quantities and high-speed video captured off-center initiation of extinction. Thus, centerline measurements did not represent the extinction state properly, given the direct contradiction to one-dimensional modeling assumptions, and the data was deemed unreliable for kinetic model validation. Flames in uniform flows were found to exhibit minimal radial dependence with extinction initiating at near-centerline locations.

PIV and electrodiffusion diagnostics of flow field, wall shear stress and mass transfer beneath three round submerged impinging jets

This paper reports on measurements of velocities, wall shear rates and mass transfer in an impinging round jet issued from a round nozzle. The effect of the nozzle shape on transfer phenomena was investigated. A round orifice perforated either on a flat plate (RO/P) or on a hemispherical surface (RO/H) was compared to a reference convergent nozzle (CONV). All the nozzles have the same exit diameter D. The exit volumetric flow rate was also conserved and led to the same Reynolds number based on the exit bulk velocity, Reb=5620. The nozzle-to-wall distance was constant and equal to 2D.The Particle Image Velocimetry technique (PIV) was used to capture the jet flow field. The limitations of the PIV technique in the vicinity of the target disk are addressed by using the electrodiffusion technique (ED) to obtain the wall shear rate distribution. The ED technique was extended for the measurement of local mass transfer distribution and global mass transfer on the target disk.The whole velocity field, wall shear rates and mass transfer in the three impinging round jets were compared. It was shown that at constant volumetric flow rate, the use of an orifice nozzle not only improves wall shear rate, but also increases local and global mass transfer. The global mass transfer on a target disk of a 3.2D diameter is 25% and 31% higher for RO/H and RO/P nozzles, respectively, compared to the reference CONV nozzle.The orifice nozzles generate narrower exit profiles relatively to the convergent nozzle. The vena contracta effect in orifice jets, more intense with RO/P than with RO/H, generates an increase of the exit centerline velocity. The hemispherical surface of RO/H nozzle stretches the flow at the exit and somewhat attenuates the vena contracta effect. The characteristic scale representation of the data confirms the origin of the observed differences between the three jets.A link between the wall shear stress and the mass transfer is revealed. The wall shear rate and the mass transfer are in a close relationship with the near field flow features, themselves affected by the nozzle geometry. Time-resolved tomographic PIV technique reveals that the wall shear rate fluctuation is related to the dynamics of the jet coherent structures.The instantaneous PIV fields indicates the formation of secondary vortices in the region where a secondary peak in local mass transfer emerges. The level of this secondary peak is sensitive to the nozzle shape. The higher is the jet acceleration, the more intense is the level of the secondary peak.

English

Thermochemical exploration of mixing and combustion of parallel hydrogen injection into supersonic vitiated air stream in a divergent duct is presented. Three-dimensional Navier Stokes equations along with twoequation turbulence models and Eddy dissipation concept (EDC)-based combustion models are solved using commercial CFD software. Chemical reaction for H2-air system is modelled by two different simple chemical kinetic schemes namely; infinitely fast rate kinetics as well as the single-step finite rate kinetics. Grid convergence of the solution is demonstrated and a grid convergence index-based error estimate has been provided. Insight into the mixing and combustion of high-speed turbulent reacting flow is obtained through the analysis of various thermochemical variables. Very good comparisons are obtained for the exit profiles for various fluid dynamical and chemical variables for the mixing case. For reacting case, the comparison between the experimental and the numerical values are reasonable. Parametric studies were carried out to study the effect of different turbulence models and turbulent Schmidt numbers. It is seen that Wilcox k-w turbulence model performed better than the other two-equation turbulence models in its class. Strong dependence of flow behaviour on turbulent Schmidt number was observed. The results indicate that simple chemical kinetics is adequate to describe the H2-air reaction in the scramjet combustor. Defence Science Journal, 2010, 60(5), pp.465-475 , DOI:http://dx.doi.org/10.14429/dsj.60.57

Numerical and experimental studies on DC plasma spray torch

One of the challenging problems in the plasma spray technique is reproducibility of the coating quality. This problem is mainly associated with arc fluctuations, which affect the plasma jet temperature and velocity, inside the plasma torch. In this study, 3D numerical models are developed to study the arc behavior inside the torch and effect of arc fluctuations on plasma jet temperature and velocity. Plasma arc is simulated for different operating parameters. Different arc sizes are predicted by using thermo-dynamical principle of minimum entropy production for given torch power. The influence of arc current and gas flow rate on the Ar–N 2 plasma arc characteristics, plasma jet and torch efficiency is presented. Predicted torch efficiencies and arc voltages are comparable with measurements. At the nozzle exit, velocity shows stronger three-dimensional effect than temperature. Plasma jets are simulated using different nozzle exit profiles obtained from the plasma arc model and their temperature and velocity distributions are clarified.