Shailendra Rana | Tribhuvan University (IOE PULCHOWK CAMPUS) (original) (raw)
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Papers by Shailendra Rana
Nucleation and Atmospheric Aerosols, 2023
International Journal of Chemical Engineering, 2021
Two-dimensional numerical simulations are conducted to study forced convection flow of different ... more Two-dimensional numerical simulations are conducted to study forced convection flow of different water-based nanofluids (ZnO, Al2O3, and SiO2) with volume fractions ( ϕ ) = 0–5% and fixed nanoparticle size (dp) = 20 nm for Reynolds numbers (Re) = 50–225 over a double backward-facing step with an expansion ratio (ER) = 2 under constant heat flux (q″ = 3000 W/m2) condition using the finite volume method. Results indicate that the local Nusselt number increases with volume fraction and Reynolds number for all working fluids. In comparison to water, the maximum heat transfer augmentation of about 21.22% was achieved by using water-SiO2 nanofluid at Re = 225 with ϕ = 5% and dp = 20 nm. Under similar conditions, the Al2O3 and ZnO nanofluids demonstrated 14.23% and 11.86% augmentation in heat transfer in comparison to water. The skin friction coefficient decreases with the increase in Re for all working fluids. No significant differences are observed in the values of skin friction coeffic...
Jordan Journal of Mechanical and Industrial Engineering, 2021
The laminar, viscous and incompressible flow of an electrically conducting fluid across an unconf... more The laminar, viscous and incompressible flow of an electrically conducting fluid across an unconfined wedge structure in the presence of a transverse magnetic field has been studied. Two-dimensional numerical simulations have been performed for Reynolds number (Re) = 1-150 and Hartmann number (Ha) = 0-10 for a fixed blockage ratio (β) = d/W = 1/30. The magnetic induction method in magnetohydrodynamics module built in ANSYS FLUENT solver has been employed to compute the flow fields. Results show that the vortex shedding can be completely eliminated if the applied magnetic field is strong enough. In the steady flow regime, it has been found that the recirculation length reduces with the increase in Ha. A minimal reduction in the drag coefficient is observed with the increase in Ha as long as unsteady flow is maintained (Ha < 7.3). However, the drag coefficient has a tendency to significantly increase with the increase in Ha for steady flow. Similarly, the lift amplitude decreases with the increase in Ha indicating a diminishing effect on the strength of vortices. A critical Hartmann number (Hacr) of 7.3 has been found for Re = 100 at which complete suppression of vortex shedding is observed.
Hindawi Publishing, 2021
Two-dimensional numerical simulations are conducted to study forced convection flow of different ... more Two-dimensional numerical simulations are conducted to study forced convection flow of different water-based nanofluids (ZnO, Al 2 O 3 , and SiO 2) with volume fractions (ϕ) � 0-5% and fixed nanoparticle size (d p) � 20 nm for Reynolds numbers (Re) � 50-225 over a double backward-facing step with an expansion ratio (ER) � 2 under constant heat flux (q″ � 3000 W/m 2) condition using the finite volume method. Results indicate that the local Nusselt number increases with volume fraction and Reynolds number for all working fluids. In comparison to water, the maximum heat transfer augmentation of about 21.22% was achieved by using water-SiO 2 nanofluid at Re � 225 with ϕ � 5% and d p � 20 nm. Under similar conditions, the Al 2 O 3 and ZnO nanofluids demonstrated 14.23% and 11.86% augmentation in heat transfer in comparison to water. e skin friction coefficient decreases with the increase in Re for all working fluids. No significant differences are observed in the values of skin friction coefficient among all working fluids at a particular Re. ese results indicate that the heat transfer enhancement has been achieved with no increased energy requirements. In addition, the velocity increases with the rise in Re, with SiO 2 nanofluid exhibiting the highest velocity as compared to other working fluids.
Two dimensional laminar viscous steady flow of an electrically conducting fluid past a square cyl... more Two dimensional laminar viscous steady flow of an electrically conducting fluid past a square cylinder placed in magnetic field have been studied. Computational simulations have been performed for Reynolds numbers and Hartmann numbers ranging from 1 to 200 and from 0 to 8 respectively for a fixed blockage ratio β = d/W = 1/8. The magnetic induction method in magnetohydrodynamics (MHD) module of ANSYS Fluent solver has been employed to compute the flow fields. The effects of transverse magnetic field on vorticity, streamlines and flow coefficients such as drag and lift coefficients have been studied. Results show that the complete suppression of vortex shedding can be achieved and establish a steady flow if a sufficiently strong magnetic field is applied. The average drag coefficient is decreased from 1.3742 to 1.0069 with the increase in Hartmann number from 0 to 3.0 as long as the flow remains unsteady. For flows in the steady regime, the drag coefficient is found to increase with ...
Journal of Thermal Engineering, 2022
Numerical simulations have been carried out to investigate the thermal-hydraulic characteristics ... more Numerical simulations have been carried out to investigate the thermal-hydraulic characteristics using water-based CuO nanofluid with volume fraction (ϕ) = 0 - 5% and fixed nanoparticle size (dp) = 20 nm at Reynolds numbers (Re) = 100 - 389 in a micro-scale backward facing step channel with and without a baffle using finite volume method. The flow is steady, laminar, and incompressible. The channel has an expansion ratio (ER) = 1.9423with a fixed step height (S) of 490 μm. To study the effect of the baffle, different geometrical configurations have been developed by varying its height and location. The height of the baffle is varied as Hb = 160 - 640 μm. The baffle is stationed on the upper wall of the channel at a dimensionless distance (D)= 1, 2, 3 and 4. The upstream, step and upper walls are thermally insulated while the lower wall downstream of the step is under a constant heat flux (qs") = 20000 W/m2. The parameters of interest for analysis are Nusselt number, skin friction coefficient and velocity distribution under different flow conditions. Results indicate that the rise in volume fraction and Reynolds number enhances the Nusselt number, indicating improved heat transfer. However, the skin friction coefficient decreases with the increment in Reynolds number. The increase in baffle height causes the Nusselt number and skin friction coefficient to rise. As the baffle is moved away from the step, the Nusselt number tends to decrease. In comparison to water, the heat transfer improved by about 164% using CuO nanofluid at Re = 389 with ϕ = 5% in the presence of the baffle with Hb = 640 μm and D = 1. However, the heat transfer enhancement has been achieved at the cost of higher pumping power requirements.
The main purpose of the paper is to study the aerodynamic and stability characteristics of a blen... more The main purpose of the paper is to study the aerodynamic and stability characteristics of a blended-wing-body (BWB) aircraft. This paper presents the estimation and selection of aircraft design parameters, planform design, reflex airfoils, and conduct thorough stability investigation of the aircraft. A conceptual design of BWB aircraft has been done and the design was analyzed and refined to achieve static stability. The CFD analysis of the BWB aircraft was done at three different values of angle-of-attack (AOA) and thus the stall AOA was determined from the computational results. The dynamic stability of the aircraft has been studied under five modes namely-short period, phugoid, Dutch-roll, roll and spiral. The static stability has been achieved with a wide positive value of static margin. Results also show that the aircraft is dynamically stable for longitudinal and lateral modes when subjected to disturbances in respective conditions. The BWB aircraft fulfils the criteria of Class I Category B aircraft and shows flight level 1 characteristics in all stability modes.
The main purpose of the paper is to study the aerodynamic and stability characteristics of a blen... more The main purpose of the paper is to study the aerodynamic and stability characteristics of a blended-wing-body (BWB) aircraft. This paper presents the estimation and selection of aircraft design parameters, planform design, reflex airfoils, and conduct thorough stability investigation of the aircraft. A conceptual design of BWB aircraft has been done and the design was analyzed and refined to achieve static stability. The CFD analysis of the BWB aircraft was done at three different values of angle-of-attack (AOA) and thus the stall AOA was determined from the computational results. The dynamic stability of the aircraft has been studied under five modes namely-short period, phugoid, Dutch-roll, roll and spiral. The static stability has been achieved with a wide positive value of static margin. Results also show that the aircraft is dynamically stable for longitudinal and lateral modes when subjected to disturbances in respective conditions. The BWB aircraft fulfils the criteria of Class I Category B aircraft and shows flight level 1 characteristics in all stability modes.
Air crash has been the subject of real concern since the development of aviation. Although airpla... more Air crash has been the subject of real concern since the development of aviation. Although airplanes, helicopters, jet planes etc. are ensured with a high level of safety, aviation accidents are likely to occur anytime and result in loss of life. Several researches and investigations have shown that human errors have been the most contributing factor of air crashes. This paper presents an analysis of all the accidents involving different kinds of aircrafts such as commercial jet planes, military aircrafts, cargo carriers etc. from 1955 to 2015 in Nepal. The probable causes stated by AAIC reports and preliminary reports are studied and analyzed, and classified under four categories namely: human factors, environmental factors, structural factors and system factors. In addition, the statistics of fatalities and accident rates is also presented in the paper.
Nucleation and Atmospheric Aerosols, 2023
International Journal of Chemical Engineering, 2021
Two-dimensional numerical simulations are conducted to study forced convection flow of different ... more Two-dimensional numerical simulations are conducted to study forced convection flow of different water-based nanofluids (ZnO, Al2O3, and SiO2) with volume fractions ( ϕ ) = 0–5% and fixed nanoparticle size (dp) = 20 nm for Reynolds numbers (Re) = 50–225 over a double backward-facing step with an expansion ratio (ER) = 2 under constant heat flux (q″ = 3000 W/m2) condition using the finite volume method. Results indicate that the local Nusselt number increases with volume fraction and Reynolds number for all working fluids. In comparison to water, the maximum heat transfer augmentation of about 21.22% was achieved by using water-SiO2 nanofluid at Re = 225 with ϕ = 5% and dp = 20 nm. Under similar conditions, the Al2O3 and ZnO nanofluids demonstrated 14.23% and 11.86% augmentation in heat transfer in comparison to water. The skin friction coefficient decreases with the increase in Re for all working fluids. No significant differences are observed in the values of skin friction coeffic...
Jordan Journal of Mechanical and Industrial Engineering, 2021
The laminar, viscous and incompressible flow of an electrically conducting fluid across an unconf... more The laminar, viscous and incompressible flow of an electrically conducting fluid across an unconfined wedge structure in the presence of a transverse magnetic field has been studied. Two-dimensional numerical simulations have been performed for Reynolds number (Re) = 1-150 and Hartmann number (Ha) = 0-10 for a fixed blockage ratio (β) = d/W = 1/30. The magnetic induction method in magnetohydrodynamics module built in ANSYS FLUENT solver has been employed to compute the flow fields. Results show that the vortex shedding can be completely eliminated if the applied magnetic field is strong enough. In the steady flow regime, it has been found that the recirculation length reduces with the increase in Ha. A minimal reduction in the drag coefficient is observed with the increase in Ha as long as unsteady flow is maintained (Ha < 7.3). However, the drag coefficient has a tendency to significantly increase with the increase in Ha for steady flow. Similarly, the lift amplitude decreases with the increase in Ha indicating a diminishing effect on the strength of vortices. A critical Hartmann number (Hacr) of 7.3 has been found for Re = 100 at which complete suppression of vortex shedding is observed.
Hindawi Publishing, 2021
Two-dimensional numerical simulations are conducted to study forced convection flow of different ... more Two-dimensional numerical simulations are conducted to study forced convection flow of different water-based nanofluids (ZnO, Al 2 O 3 , and SiO 2) with volume fractions (ϕ) � 0-5% and fixed nanoparticle size (d p) � 20 nm for Reynolds numbers (Re) � 50-225 over a double backward-facing step with an expansion ratio (ER) � 2 under constant heat flux (q″ � 3000 W/m 2) condition using the finite volume method. Results indicate that the local Nusselt number increases with volume fraction and Reynolds number for all working fluids. In comparison to water, the maximum heat transfer augmentation of about 21.22% was achieved by using water-SiO 2 nanofluid at Re � 225 with ϕ � 5% and d p � 20 nm. Under similar conditions, the Al 2 O 3 and ZnO nanofluids demonstrated 14.23% and 11.86% augmentation in heat transfer in comparison to water. e skin friction coefficient decreases with the increase in Re for all working fluids. No significant differences are observed in the values of skin friction coefficient among all working fluids at a particular Re. ese results indicate that the heat transfer enhancement has been achieved with no increased energy requirements. In addition, the velocity increases with the rise in Re, with SiO 2 nanofluid exhibiting the highest velocity as compared to other working fluids.
Two dimensional laminar viscous steady flow of an electrically conducting fluid past a square cyl... more Two dimensional laminar viscous steady flow of an electrically conducting fluid past a square cylinder placed in magnetic field have been studied. Computational simulations have been performed for Reynolds numbers and Hartmann numbers ranging from 1 to 200 and from 0 to 8 respectively for a fixed blockage ratio β = d/W = 1/8. The magnetic induction method in magnetohydrodynamics (MHD) module of ANSYS Fluent solver has been employed to compute the flow fields. The effects of transverse magnetic field on vorticity, streamlines and flow coefficients such as drag and lift coefficients have been studied. Results show that the complete suppression of vortex shedding can be achieved and establish a steady flow if a sufficiently strong magnetic field is applied. The average drag coefficient is decreased from 1.3742 to 1.0069 with the increase in Hartmann number from 0 to 3.0 as long as the flow remains unsteady. For flows in the steady regime, the drag coefficient is found to increase with ...
Journal of Thermal Engineering, 2022
Numerical simulations have been carried out to investigate the thermal-hydraulic characteristics ... more Numerical simulations have been carried out to investigate the thermal-hydraulic characteristics using water-based CuO nanofluid with volume fraction (ϕ) = 0 - 5% and fixed nanoparticle size (dp) = 20 nm at Reynolds numbers (Re) = 100 - 389 in a micro-scale backward facing step channel with and without a baffle using finite volume method. The flow is steady, laminar, and incompressible. The channel has an expansion ratio (ER) = 1.9423with a fixed step height (S) of 490 μm. To study the effect of the baffle, different geometrical configurations have been developed by varying its height and location. The height of the baffle is varied as Hb = 160 - 640 μm. The baffle is stationed on the upper wall of the channel at a dimensionless distance (D)= 1, 2, 3 and 4. The upstream, step and upper walls are thermally insulated while the lower wall downstream of the step is under a constant heat flux (qs") = 20000 W/m2. The parameters of interest for analysis are Nusselt number, skin friction coefficient and velocity distribution under different flow conditions. Results indicate that the rise in volume fraction and Reynolds number enhances the Nusselt number, indicating improved heat transfer. However, the skin friction coefficient decreases with the increment in Reynolds number. The increase in baffle height causes the Nusselt number and skin friction coefficient to rise. As the baffle is moved away from the step, the Nusselt number tends to decrease. In comparison to water, the heat transfer improved by about 164% using CuO nanofluid at Re = 389 with ϕ = 5% in the presence of the baffle with Hb = 640 μm and D = 1. However, the heat transfer enhancement has been achieved at the cost of higher pumping power requirements.
The main purpose of the paper is to study the aerodynamic and stability characteristics of a blen... more The main purpose of the paper is to study the aerodynamic and stability characteristics of a blended-wing-body (BWB) aircraft. This paper presents the estimation and selection of aircraft design parameters, planform design, reflex airfoils, and conduct thorough stability investigation of the aircraft. A conceptual design of BWB aircraft has been done and the design was analyzed and refined to achieve static stability. The CFD analysis of the BWB aircraft was done at three different values of angle-of-attack (AOA) and thus the stall AOA was determined from the computational results. The dynamic stability of the aircraft has been studied under five modes namely-short period, phugoid, Dutch-roll, roll and spiral. The static stability has been achieved with a wide positive value of static margin. Results also show that the aircraft is dynamically stable for longitudinal and lateral modes when subjected to disturbances in respective conditions. The BWB aircraft fulfils the criteria of Class I Category B aircraft and shows flight level 1 characteristics in all stability modes.
The main purpose of the paper is to study the aerodynamic and stability characteristics of a blen... more The main purpose of the paper is to study the aerodynamic and stability characteristics of a blended-wing-body (BWB) aircraft. This paper presents the estimation and selection of aircraft design parameters, planform design, reflex airfoils, and conduct thorough stability investigation of the aircraft. A conceptual design of BWB aircraft has been done and the design was analyzed and refined to achieve static stability. The CFD analysis of the BWB aircraft was done at three different values of angle-of-attack (AOA) and thus the stall AOA was determined from the computational results. The dynamic stability of the aircraft has been studied under five modes namely-short period, phugoid, Dutch-roll, roll and spiral. The static stability has been achieved with a wide positive value of static margin. Results also show that the aircraft is dynamically stable for longitudinal and lateral modes when subjected to disturbances in respective conditions. The BWB aircraft fulfils the criteria of Class I Category B aircraft and shows flight level 1 characteristics in all stability modes.
Air crash has been the subject of real concern since the development of aviation. Although airpla... more Air crash has been the subject of real concern since the development of aviation. Although airplanes, helicopters, jet planes etc. are ensured with a high level of safety, aviation accidents are likely to occur anytime and result in loss of life. Several researches and investigations have shown that human errors have been the most contributing factor of air crashes. This paper presents an analysis of all the accidents involving different kinds of aircrafts such as commercial jet planes, military aircrafts, cargo carriers etc. from 1955 to 2015 in Nepal. The probable causes stated by AAIC reports and preliminary reports are studied and analyzed, and classified under four categories namely: human factors, environmental factors, structural factors and system factors. In addition, the statistics of fatalities and accident rates is also presented in the paper.