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Abstract:

This paper, reports the numerical results of the turbulent flow characteristics and turbulent quantities when a triangular object is placed at the exit of two nozzles. The fluid flow at the entrance of the nozzles is considered isothermal and incompressible. Three turbulence k-ε models are used to study the jets interaction and its resulting characteristics. The numerical method is first validated with the available experimental results for a configuration where no object is placed between nozzles. Numerical simulations are carried out for fixed turbulence intensity at the nozzles exit (3%), and for Reynolds numbers varied from 2.10³ to 10⁴. Results reveal that the existence of a solid object between the dual jets affects the location of the merge and combined points. The merge point is pushed downstream of the flow, and the corresponding axial velocity of the combined point is reduced for all Reynolds numbers. The turbulent kinetic energy field is also affected, either in the near field or in the far field for all Reynolds numbers. We have concluded also that the Realizable k-ε model overestimates velocity and turbulent kinetic energy fields compared to the other models.

Keywords:

flow interaction,merge point,combined point,turbulence model,

Refference:

I. Abbasalizadeh M., Jafarmadar S. and Shirvani H., “The effects of pressure difference in nozzle’s two phase flow on the quality of exhaust mixture”, International Journal of Engineering Transactions B: Applications, vol. 26, no. 5, pp: 553-562, 2013.
II. Anderson E. A. and Spall R. E., “Experimental and numerical investigation of two-dimensional parallel jets”, Transactions of ASME, Journal of Fluids Engineering, vol. 123, no. 2, pp: 401-406, 2001.
III. Azim M. A., “Characteristics of twin axisymmetric free jets”, Proceedings of the international Conference on Mechanical Engineering, Bangladesh, 2009.
IV. Boussoufi M., Sabeur-Bendehina A., El Ganaoui M., Morsli S. and Ouadha A., Numerical simulation of the flow field analysis in the mixing twin jets, Energy Procedia, vol. 139, pp: 161-166, 2017.
V. Elbanna H., Sabbagh J. A. and Rashed M. I. I, “Interception of two equal turbulent jets”, AIAA Journal, vol. 23, no. 7, pp: 985-986, 1985.
VI. Elbanna H., Gahin S. and Rashed M. I. I., “Investigation of two plane parallel jets”, AIAA Journal, vol. 21, no. 7, 986-991, 1983.
VII. Erdem D. and Ath V., “Interaction of two parallel rectangular jets”, 23rd International Congress of Aeronautical Sciences, Canada, 2002.
VIII. Gao J., Xu X. and Li X., “Numerical simulation of supersonic twin-jet noise with high-order finite difference scheme”, AIAA Journal, vol. 56, no. 1, pp: 290-300, 2018.
IX. Hnaien N., Marzouk Khairallah S., Ben Aissia H and Jay J, “Numerical study of interaction of two plane parallel jets”, International Journal of Engineering TRANSACTIONS A: Basics, vol. 29, no. 10, pp: 1421-1430, 2016.
X. Karnam A., Baier F., Gutmark E. J., Jeun J., Wu G. J. and Lele S. K., “An investigation into flow field interactions between twin supersonic rectangular jets”, AIAA Scitech forum, January 2021.
XI. Kwon S. J. and Seo I. W., “Reynolds number effects on the behavior of a non-buoyant round jet”, Experiments in Fluids, vol. 38, no. 6, pp: 801-812, 2005.
XII. Lin Y. F. and Sheu M. J., “Interaction of parallel turbulent plane jets”, AIAA Journal, vol. 29, no. 9, pp: 1372-1373, 1991.
XIII. Lin Y. F. and Sheu M. J., “Investigation of two plane parallel unventilated jets”, Experiments in Fluids, vol. 10, no. 1, pp: 17-22, 1990.
XIV. Mi J. and Nathan G. J., “Statistical properties of turbulent free jets issuing from nine differently-shaped nozzles”, Flow, Turbulence and Combustion, vol. 84, pp: 583-606, 2010.
XV. Naseri Oskouie R., Tachie M. F. and Wang B. C., “Effect of nozzle spacing on turbulent interaction of low-aspect-ratio twin rectangular jets”, Flow, Turbulence and Combustion, vol. 103, no. 2, pp: 323, 2019.
XVI. Nasr A. and Lai J. C. S., “Two parallel plane jets: mean flow and effects of acoustic excitation”, Experiments in Fluids, vol. 22, no. 3, pp: 251-260, 1997.
XVII. Pandey K. M. and Kumar V., “CFD analysis of four jet flow at Mach 1.74 with Fluent software”, International Journal of Environmental Science and Development, vol. 1, no. 5, pp: 423-428, 2010.
XVIII. Pandey K. M., Kumar V. and Srivastava P., “CFD analysis of twin jet supersonic flow with Fluent software”, Current Trends in Technology and Sciences, vol. 1, no. 2, pp: 84-91, 2012.
XIX. Patankar S. V., Numerical heat transfer and fluid flow, Mac Graw Hill, New York, 1980.
XX. Shih T. H., Liou W. W., Shabbir A., Yang Z. and Zhu J., A new k-ε eddy viscosity model for high Reynolds number turbulent flows, Computer and Fluids, vol. 24, no. 3, pp: 227-238, 1995.
XXI. Sourav S., Hossain Rifat A. and Taher Ali M. A., “Effects of Reynolds number on twin circular jets at a small space ratio”, International Journal of Research and Scientific Innovation, vol. 7, no. 8, pp: 248-252, 2020.
XXII. Spall R. E., Numerical study of buoyant plane parallel jets, Journal of Heat Transfer, vol. 124, no. 6, pp: 1210-1212, 2002.
XXIII. Tanaka E., “Experiments on the combined flow of dual jet: the interference of two-dimensional parallel jets”, Bulletin JSME, vol. 17, no. 109, pp: 920- 927, 1974.
XXIV. Tanaka E., “The interference of two dimensional parallel jets”, Bulletin JSME, vol. 13, no. 56, pp: 272-280, 1970.
XXV. Tenchine D. and Moro J. P., “Experimental and numerical study of coaxial jets”, Proceedings of the 8th Int topical meeting on nuclear reactor thermal-hydraulics, Japan, vol. 3, pp: 1381-1387, 1997.
XXVI. Wang C. S., Lin Y. F. and Sheu M. J., “Measurements of turbulent inclined plane dual jets”, Experiments in Fluids, vol. 16, no. 1, pp: 27-35, 1993.
XXVII. Zheng X., Jian X., Wei J. and Wenzheng D., “Numerical and experimental investigation of near-field mixing in parallel dual round jets”, International Journal of Aerospace Engineering, vol. 1, pp: 1-12, 2016.

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Abstract:

This work primarily focuses on the polymer matrix composite comprising Nylon 6 and Basalt fibre pooled together for the purpose of wear reduction in spur gear material. The method employed here using the Nylon 6 and Basalt fibre is employed through the Injection Moulding method, the fibres are combined in the ratio of (80:20) & (70:30). This project aims to focus on the mechanical properties such as tensile, compression, and impact test as per ASTM standards. Later Finite Element models were then developed to simulate the impact, tensile, and wear characteristics behavior of the tested material,

Keywords:

Compressive Strength,Split Tensile Strength,GGBS,Metakaoline,Regression Analysis,

Refference:

I. A. J. Mertens and S. Senthilvelan, “Effect of Mating Metal Gear Surface Texture on the Polymer Gear Surface Temperature,” Mater. Today Proc., vol. 2, no. 4–5, pp. 1763–1769, 2015.

II. K. Mao, W. Li, C. J. Hooke, and D. Walton, “Polymer gear surface thermal wear and its performance prediction,” Tribol. Int., vol. 43, no. 1–2, pp. 433–439, 2009.

III. K. Mao, W. Li, C. J. Hooke, and D. Walton, “Friction and wear behaviour of acetal and nylon gears,” Wear, vol. 267, no. 1–4, pp. 639–645, 2009.

IV. K. Mao, P. Langlois, Z. Hu, K. Alharbi, X. Xu, M. Milson, W. Li, C. J. Hooke, and D. Chetwynd, “The wear and thermal mechanical contact behaviour of machine cut polymer gears,” Wear, vol. 332–333, pp. 822–826, 2015

V. M. C. S. Ribeiro, S. P. B. Sousa, and P. R. O. Nóvoa, “An investigation on fire and flexural mechanical behaviors of nano and micro polyester composites filled with SiO 2 and Al 2 O 3 particles,” Mater. Today Proc., vol. 2, no. 1, pp. 8–19, 2015.

VI. S. Xue and I. Howard, “Dynamic modelling of flexibly supported gears using iterative convergence of tooth mesh stiffness,” Mech. Syst. Signal Process., pp. 1–22, 2016.

VII. S. Senthilvelan and R. Gnanamoorthy, “Effect of rotational speed on the performance of unreinforced and glass fiber reinforced Nylon 6 spur gears,” Mater. Des., vol. 28, no. 3, pp. 765–772, 2007.

VIII. V. Savaria, F. Bridier, and P. Bocher, “Predicting the effects of material properties gradient and residual stresses on the bending fatigue strength of induction hardened aeronautical gears,” Int. J. Fatigue, pp. 1–39, 2015.

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Abstract:

 In this article, the effect of temperature-dependent viscosity (TVD) on the unsteady laminar flow and heat transfer (HT) of a viscous incompressible fluid due to a rotating disc (RD) has been investigated numerically by exploiting an in-house numerical code. A set of time-dependent, axisymmetric, and non-linear partial differential equations which govern the fluid flows and heat transfer are reduced to non-linear local non-similarity ordinary differential equations by introducing a newly developed group of transformations for different time regimes. Three different solution methods, such as, (i) perturbation solution method for small t, (ii) asymptotic solution method for large t, and (iii) implicit finite difference method for the entire t regime, have been applied to solve the resulting equations treating t as the time-dependent rotating parameter. The local radial skin friction, tangential skin friction and the heat transfer are computed at the surface of the disc for different numerical parameters, such as, Prandtl number, Pr and the viscosity-variation parameter, e. Besides, the key dimensionless quantities such as velocity and temperature profiles, which are inherently linked with the boundary layer thickness, are presented graphically for different values of e while Pr = 0.72. It is found that the dimensionless radial, tangential and axial velocity profiles decrease as e increases, and consequently, the momentum boundary layer thickness is decreased. On the other hand, the non-dimensional temperature profiles are increased owing to the increasing values of e, and this effect eventually leads to a small increment in the thermal boundary layer thickness.  

Keywords:

Unsteady flow,heat transfer (HT),temperature-dependent viscosity (TDV),laminar flow,rotating disc (RD),

Refference:

I. A. Mehmood, M. Usman, Heat transfer enhancement in rotating disk boundary-layer, Thermal Sciences, vol. 22 pp: 2467-248, 2018.

II. A. Nilankush, B. Raju, P. K. Kundu, Influence of hall current on radiative nanofluid flow over a spinning disk: a hybrid approach, Physica E: Low dimensional systems and nanostructures, vol. 111,
pp: 103-112, 2019.

III. E. R. Benton, On the flow due to a rotating disc, Journal of Fluid Mechanics, vol. 24, pp: 781- 800, 1966.

IV. E. M. Sparrow, J. L. Gregg, Heat transfers from a rotating disk to a fluid of any Prandtl number, ASME Journal of Heat Transfer, vol. 81, pp: 249-251, 1959.

V. F. Kreith, Convection heat transfer in rotating systems, Advances in Heat Transfer, vol. 5, pp:129–251, 1969.

VI. G. K. Batchelor, Note on a class of solutions of the Navier-Stokes equations representing steady non-rotationally symmetric flow, The Quarterly Journal of Mechanics and Applied Mathematics, vol. 4, pp. 29-41, 1951.

VII. H. Ockendon, An asymptotic solution for steady flow above an infinite rotating disc with suction, The Quarterly Journal of Mechanics and Applied Mathematics, vol. 25, pp: 291-301, 1972.

VIII. H. B. Keller, Numerical methods in the boundary layer theory, Annual Annual Review of Fluid Mechanics, vol. 10, pp: 417-433, 1978.

IX. I. V. Shevchuk, Convective heat and mass transfer in rotating disk systems, Lecture Notes in Applied and Computational Mechanics, vol. 45, Springer-Verlag Berlin Heidelberg, 2009.

X. J. P. Hartnett, Heat transfer from a non-isothermal rotating disc in still air, ASME Journal of Applied Mechanics, vol. 26, no. 4, pp: 672-673,
1959.

XI. J. T. Stuart, On the effect of uniform suction on the steady flow due to a rotating disc, The uarterly Journal of Mechanics and Applied Mathematics, vol. 7, pp: 446-457, 1954.

XII. J. C. Butcher, Implicit Rungee-Kutta process, Journal of Mathematics of Computation, vol. 18, no. 85, pp. 50-64,1964.

XIII. J. M. Owen, R. H. Rogers, Flow and heat transfer in rotating disc systems: Rotor-stator systems, Research Studies, Taunton, U.K. and John Wiley, NY, USA, 1989.

XIV. J. F. Brady, L. Durlofsky, On rotating disk flow, Journal of Fluid Mechanics, vol. 175, pp: 363-394, 1987.

XV. J. X. Ling, A. Dybbs, Forced convection flow over a flat plate submerged in a porous medium with variable viscosity case, Conference of ASME, paper no. 87- WA/TH-23, New York, 1987.

XVI. J. Herrero, J. A. C. Humphrey, F. Giralt, Comparative analysis of coupled flow and heat transfer between co-rotating discs in rotating and fixed cylindrical enclosures, ASME Heat Transfer Division, vol. 300, pp: 111-121, 1994.

XVII. M. G. Rogers, G. N. Lance, The rotationally symmetric flow of a viscous fluid in presence of infinite rotating disc, Journal of Fluid Mechics, vol. 7, pp: 617-631, 1960.

XVIII. M. A. Hossain, S. M. Munir, Mixed convection flow from a vertical flat plate with temperature dependent viscosity, International Journal of Thermal Sciences, vol. 39, no. 2, pp: 173-183, 2000.

XIX. M. A. Hossain, A. Hossain, M. Wilson, Unsteady flow of viscous incompressible fluid with temperature-dependent viscosity due to arotating disc in presence of transverse magnetic field and heat transfer,
International Journal of The rmal Sciences, vol. 40, no. 1, pp: 11-20, 2001.

XX. M. A. Hossain, S. Kabir, D. A. S. Rees, Natural convection of fluid with variable viscosity from a heated vertical wavy surface, Journal of Applied Mathematics and Physics, Vol. 53 pp: 48-52, 2002.

XXI. M. M. Awad, Heat transfer from a rotating disk to fluids for a wide range of Prandtl numbers using the asymptotic model, ASME Journal Heat Transfer, vol. 130, no.014505, pp: 1-4, 2008.

XXII MD. Shamshuddin, S. R. Mishra, O. A. Bég, A. Kadir, Numerical study of heat transfer and viscous flow in a dual rotating extendable disk system with a non‐Fourier heat flux model, Heat Transfer Asian
Research, vol. 48, pp: 1-25, 2018.

XXIII. M. Ibrahim, Numerical analysis of time-dependent flow of viscous fluid due to a stretchable rotating disk with heat and mass transfer, Results in Physics, vol. 18 , no. 103242, pp:1-6, 2020.

XXIV. M. Ramzan, N. S. Khan, P. Kumam, A numerical study of chemical reaction in a nanofluid flow due to rotating disk in the presence of magnetic field, Scientific Reports, vol. 11, no. 19399, pp:1-24, 2021.

XXV. N. G. Kafoussias, D. A. S. Rees, J. E. Daskalakis, Numerical study of the combined free and forced convective laminar boundary layer flow past a vertical isothermal flat plate with temperature dependent viscosity, Acta Mechanica, vol. 127, pp: 39-50, 1998.

XXVI. P. R. Nachtshiem, P. Swigert, Satisfaction of the asymptotic boundary conditions in numerical solution of the system of non-linear equations of boundary layer type, NASA TND-3004, 1965.

XXVII. P. R. N. Childs, Rotating flow, 1st Edition, Butterworth–Heinemann, UK, 2010.

XXVIII. S. Ostrach, P. R. Thorton, Compressible laminar flow and heat transfer about a rotating isothermal disc, NACA Technical Note 4320, 1958.

XXIX S. P. Anjali Devi1, R. Uma Devi, On hydromagnetic flow due to a rotating disk with radiation effect, Nonlinear Analysis: Modelling and Control, vol. 16, pp: 17–29, 2011.

XXX. S. Imayama, P. H. Alfredsson, R. J. Lingwood, Experimental study of rotating-disk boundary-layer flow with surface roughness,
Journal of Fluid Mechanics, vol. 786, no. 5, pp:5-28, 2016.

XXXI. T. Von Karman, Üeber laminare und turbulente reibung, ZAMM, vol.
4, pp: 233-252, 1921.

XXXII. T. Cebeci, P. Bradshaw, Physical and computational aspects of
convective heat transfer, Springer-Verlag, New-York, 1984.

XXXIII. T. Hayat, M. Ijaz Khan, A. Alsaedi, M. Imran Khan, Joule heating and
viscous dissipation in flow of nanomaterial by a rotating disk,
International Communications in Heat Mass Transfer, vol. 89, pp: 190-
197, 2017.

XXXIV. U. T. Bödewat, Die drehströmung üeber festem grunde, ZAMM, vol. 20 , pp: 241-253, 1940.

XXXV. W. G. Cochran, The flow due to a rotating disc, Proceedings of the
Cambridge Philosophical Society, vol.30, pp.365-37, 1934.

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Abstract:

In this paper, we consider a system with two heterogeneous servers Markovian queue. In which the system breakdown occurs when the system is in busy mode. Immediately the system undergoes repair. After completion of the repair, the system either undergoes optional repair mode or becomes busy mode based on a Bernoulli schedule. It is assumed that the number of repairs follows the Poisson process and the repair periods follow an exponential distribution. The model has been solved in steady-state using the matrix analytic method. Some performance measures and numerical results are obtained.

Keywords:

Markovian queue,heterogeneous server,breakdown,repair,steady-state solution,matrix-Geometric method,

Refference:

I. Cheng, C.Y., and Liu, H.H., (2010) The-finite – time -period preventive maintenance policies with failiure rate reduction under a warranty consideration, Journal of the Chinese institute of industrial Engineers, v.27, 81-89.
II. Desmit, J.H.A., (1983) A numerical solution for the multi server queue with hyper exponential service times, Oper. Res. Lett, v.2, 217-224.
III. Durilk,I., (2005) Inżynieria zarządzania Cz. II – strategie wytwarzania.Gdańsk: Wydawnictwo Placet.
IV. Heffer, J.C., (1969) Steady state solution of the M/Ek/C (F1F0) queuing system, CORSJ. v.7, 16-30.
V. Kalyanaraman, R., and Senthilkumar, R., (2018a) Heterogeneous server Markovian queue with switching of service modes,Annamalai University Science Journal, v.51(1), 1-8.
VI. Kalyanaraman, R., and Senthilkumar, R., (2018b) Heterogeneous server Markovian queue with restricted Admissibility and with Reneging, Mathematical Sciences International Research Journal, v.7 (1), 309-315.
VII. Kalyanaraman, R., and Senthilkumar, R., (2018c) Heterogeneous server Markovian queue with restricted Admissibility of customers,Journal of Applied Mathematics Analysis and Applications, v.7(1), 85-97.
VIII. Latouche, G and Neuts, M.F., (1980) Efficient algorithmic solutions to exponential tandem queues with blocking, SIAM J. Algebraic Discrete Math., v.1, 93-106.
IX. Lucantoni, D.M., (1979) A GI/M/C queue with a different service rate for customers who need not wait an algorithmic solution, Technical Rep. Univ. of Delware, USA.
X. Mitrany, I.L., and Avi-Itzhak, B., (1968) A many-server queue with service interruptions. Operations Research, v.16, pp. 628-638.
XI. Neuts, M.F., (1978) Markov chains with applications in queueing theory which have a matrix-geometric invariant probability vector, Adv. Appl. Probab., 10, 185-212.
XII. Neuts, M.F., (1981) Matrix-Geometric solution in stochastic models,Vol 2 of John Hopkins series in the Mathematical Sciences,John Hopkins University press, Baltimore,Md,USA. J. Mech. Cont. & Math. Sci., Vol.-17, No.-5, May (2022) pp 43-55 Kalyanaraman. R 55
XIII. Neuts, M.F., and Lucantoni, D.M., (1979) A Markovian queue with N servers subject to breakdowns and repairs. Management Science, v.25, pp. 849-861.
XIV. Schouten, F.A.V.D.D., and Wartenhorst, P., (1993) A two machine repair model with variable repair rate,Noval Research Logistics, v.40, 495-23.
XV. Sheng, Li .Lv., Jing, Bo.Li., and De, Quan.Yue., (2011) Unreliable multiserver machine repairable system with variable breakdown rates,Journal of the Chinese Institute Industrial Engineers, V.28(5), pp-400-409.
XVI. Singh, V.P., (1970) Two servers Markovian queues with balking, Heterogeneous vs Homogeneous servers, Oper.Res., v.18(1), 145-159.
XVII. Singh, V.P., (1973) Queue dependence-servers, Jr. of Eng. Maths, v.7 (2), 123-126.
XVIII. Vinod, B., (1985) Unreliable queueing systems. Computers and Operations Research, v.12, pp. 322-340.
XIX. Wang, K.H., and Chang, Y.C., (2002) Cost analysis of a finite M/M/R queueing system with balking, reneging and server breakdowns. Mathematical Methods of Operations Research, v.56, 169-180.
XX. Wartenhosrt, P., (1995) N parallel Queueing systems with server breakdowns and repair. European Journal of Operational Research, v.82, pp. 302-322.
XXI. Witold BIAŁY and Juraj RUŽBARSKÝ (2018) Breakdown Cause and Effect Analysis. Case Study, Management Systems in Production Engineering, v.26 (2), pp. 83-87.
XXII. Wu, C.H., Lee, W.C., Ke, J.C., and Liu,T.H., (2014) Optimization analysis of on unreliable multi server queue with a controllable repair policy, Computer and Operation research, v.49, pp-83-96.

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Abstract:

In the present work, the preliminary finding of possibilities of heat transfer and pressure drop is reported across the shell and tube arrangement cross-flow heat exchanger. The heat exchanger consists of cold-water flows through the bundle of circular tubes and hot air across the shell. Like in the conventional arrangement, the flow in adjacent rows of tubes is normal to the fluid flow in the shell in the cross-flow arrangement. The three-dimensional turbulent flow region is modelled by employing ANSYS FLUENT 21.0. The standard k-ε model is used to model the turbulence flow. A SIMPLE algorithm scheme is applied to link the pressure and velocity fields inside the domain for air fluids. The heat transfer in the water inside the tubes is represented by a convective boundary condition. The tube flow Reynolds number was fixed at 2200 and the shell flow Reynolds number was varied from 6000 to 10000 in the turbulent zone.  The purpose of this paper is to determine temperature reduction and pressure drop across the tube bundle. The simulation will predict the temperature of the airstream at the heat exchanger exit and the pressure drop. The results indicated that there is a significant amount of temperature drop in the air that releases the heat due to forced convection and temperature drop continues in the turbulent region of the incoming fluid.

Keywords:

Cross flow heat exchanger,Temperature drop,Pressure drop,Turbulent flow,

Refference:

I. Alok Vyas et al. (2013). An Experimental Analysis Study to Improve Performance of Tubular Heat Exchanger. Journal of Engineering Research and Applications, Vol. 3, Issue 6, pp.1804-1809.

II. A. Dewan, P. Mahanta, Sumithra, K. Raju, Suresh, P. Kumar. (2004). Review of passive heat transfer augmentation techniques. Proc. Instn. Mech. Engrs, Part A – J. Power Energy, 218(7), 509-526.

III. A.S. Krishnan, P. Gowtham. (2017). Computational study of the staggered and double cross flow heat exchanger, Defence Science Journal, Vol. 67, No. 4, pp. 396-400.
IV. A. Taufiq, P.S. Dhakar. (2020). CFD analysis of plate heat exchanger by using Ansys, International Journal of Research and Analytical Reviews (IJRAR), Volume 7, Issue 3.
V. P. Paikert. (1986). Air cooled heat exchanger: thermal and hydraulic design of heat exchanger. Vol. 3, Hemisphere Publishing Corporation.

VI. W.M. Kays, A.L. London. (1984). Compact Heat Exchanger 3rd edition, McGraw-Hill Book Co.

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