Prapamonthon, Prasert

Preferred name

Alternative Name

PRAPAMONTHON, Prasert

Prapamonthon, P.

Main Affiliation

International Academy of Aviation Industry

prasert.pr@kmitl.ac.th

Now showing 1 - 10 of 16

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Numerically thermal analysis of a turbine vane at high temperature
(2019-11-26)
Prapamonthon, P.
;
Yooyen, S.
;
Sleesongsom, S.
Using conjugate heat transfer, thermal analysis of a turbine vane coated with thermal barrier coating (TBC) at a high temperature is presented. Numerical results are carried out at two turbine inlet temperatures (T <inf>∞</inf>) i.e. 783 K (low) and 1566 K (high) under two turbulence intensities (Tus) i.e. 8.3% and 16.6%. The main findings of this research are that for both Tus, the metal surface temperature reduction at the high temperature is higher than that at the low temperature because of the lower heat-flux ratio at the higher temperature. Based on the metal temperature reduction, the increasing inlet temperature has a greater influence than the increasing turbulence intensity. The results also indicate that at T <inf>∞</inf> = 783 K, on the pressure side (PS) the metal surface temperature reduction at Tu = 8.3% is lower than that at Tu = 16.6%, while on the suction side (SS) no significant difference happens when Tu increases. Interestingly, an inverse phenomenon happens for both PS and SS, that is the metal surface temperature reduction at Tu = 8.3% increases above that at Tu = 16.6% when T <inf>∞</inf> increases. This discrepancy may suggest the instability of the surface heat-flux ratio due to complex heat convection at the different inlet temperatures.
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Numerical prediction of cooling performance sensitivity of 1st stage nozzle guide vane under aerothermal conditions
(2019-01-01)
Prapamonthon, Prasert
;
Yin, Bo
;
Yang, Guowei
;
Zhang, Mohan
To obtain high power and thermal efficiency, the 1st stage nozzle guide vanes of a high-pressure turbine need to operate under serious circumstances from burned gas coming out of combustors. This leads to vane suffering from effects of high thermal load, high pressure and turbulence, including flow-separated transition. Therefore, it is necessary to improve vane cooling performance under complex flow and heat transfer phenomena caused by the integration of these effects. In fact, these effects on a high-pressure turbine vane are controlled by several factors such as turbine inlet temperature, pressure ratio, turbulence intensity and length scale, vane curvature and surface roughness. Furthermore, if the vane is cooled by film cooling, hole configuration and blowing ratio are important factors too. These factors can change the aerothermal conditions of the vane operation. The present work aims to numerically predict sensitivity of cooling performances of the 1st stage nozzle guide vane under aerodynamic and thermal variations caused by three parameters i.e. pressure ratio, coolant inlet temperature and height of vane surface roughness using Computational Fluid Dynamics (CFD) with Conjugate Heat Transfer (CHT) approach. Numerical results show that the coolant inlet temperature and the vane surface roughness parameters have significant effects on the vane temperature, thereby affecting the vane cooling performances significantly and sensitively.
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A web-based semi-empirical numerical tool for accessible liquid swirl injector design
(2025-01-01)
Uhthalye, Thitut
;
Prapamonthon, Prasert
Swirl injectors are vital components to liquid rocket engine combustion intensification, offering high-performance propellant atomisation with relative ease of manufacture. However, despite their widespread use and utility, comprehensive, publicly available practical design methodologies remain scarce in the literature. To address this gap, this paper presents a web-based JavaScript tool employing an iterative semi-empirical numerical method for rapid first-order approximation design of general tangential inlet-type monopropellant and bipropellant liquid swirl injector geometries, based chiefly on the approach described by Bazarov et al. (2004). The tool calculates key geometric and flow parameters—including nozzle radius, radial inlet positions, spray cone angle, and Reynolds numbers—based on user-specified operating conditions such as pressure drop, fluid properties, and geometric coefficients. Special emphasis is given to the efficient implementation of the algorithm for rapid iteration. A computational fluid dynamics validation comparing the computed values against expected flow characteristics is ongoing, with initial results showing promising agreement in limited test cases. Analyses quantifying variances and defining valid regimes of sensible results are in-progress. Additionally, a structured design workflow is also proposed, addressing key limitations such as model prediction deviation due to insufficient air core formation in small injectors. This accessible computation tool aims to assist engineers and students in the predictable and iterative development of swirl injectors.
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EFFECTS OF VANE TRAILING EDGE DETERIORATION ON FLOW PHENOMENA: A CFD SIMULATION OF BROKEN SCENARIOS
(2023-01-01)
Thammachote, Benyapa
;
Premyothin, Jitlada
;
Tanpradit, Ditthaphat
;
Wongsatanawarid, Atikorn
;
Dipasquale, Daniele
To achieve high thermal and propulsive efficiencies from an aircraft powerplant using an air-breathing system, the turbine inlet temperature (TIT), a critical design-limit variable, must rise. However, the increment of the TIT is limited by the survivability of the turbine material. Beyond the safety zone of the material, the operation can end in failure. For this reason, the turbine nozzle guide vane (NGV) is a critical component of gas turbine engines because it must operate in hot gas environments. Due to the constraints of effective cooling and the thinnest possible shape of the trailing edge (TE), this region can be suddenly or gradually deteriorated by cracks when the turbine is in long-term operation. This situation can have a seriously negative effect on the engine's performance because the flow field and heat phenomena are different from the usual conditions. Therefore, the problem of vane TE damage is very challenging, and sustainable solutions require a thorough understanding of flow physics and heat transfer mechanisms. A three-dimensional CFD simulation with the SST k-ω turbulence model is used in this work to investigate flow phenomena at the vane trailing edge while subjected to damage effects. The profile of the Mark II vane is used to create vane boundaries in the computational domain. The computational mesh is generated by ICEM and 18 layers are added to the vane surface to capture the flow in the boundary layer. The minimum quality of the mesh is 0.2 and y+ is less than 4.5. The FLUENT software is used as the solver, with second order upwind discretization. Under the compressible flow model, air is used as the burned gas. Broken scenarios in both the streamwise and spanwise directions are presented in a very simplistic manner, with a short, shallow cutback expanding into a long, deep one, namely, 0.1 cm x 1 cm to 0.3 cm x 3 cm. The convergence of the numerical results is considered by the residual of the governing equations. Boundary conditions are set to be the same as experimental data reported by NASA so that numerical results in terms of the pressure distribution along the vane midspan can be validated. The results predicted by the SST k-w turbulence model can provide an acceptable agreement with the experiment. For subsequent simulations, numerical results involving turbulent flow, such as turbulent viscosity, turbulent kinetic energy, vorticity, and streamlines, are compared, and discussed. The findings show that vane TE damage has a significant impact on fluid in motion, particularly the phenomenon of turbulent viscosity. This suggests that heat convection is disrupted.
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NUMERICAL INVESTIGATION ON DAMAGE SCENARIOS OF VANE TRAILING EDGE USING THERMO-FLUID-STRUCTURAL ANALYSIS
(2025-01-01)
Jeatrakul, Karn
;
Tanpradit, Ditthaphat
;
Prapamonthon, Prasert
;
Raja, Vijayanandh
;
Ke, Zhaoqing
Gas-turbine nozzle vanes are used to increase the velocity magnitude of hot gas exiting the combustor. Thus, the vanes must operate at high turbine inlet temperatures (TITs). Essentially, the higher the turbine inlet temperature, the greater the thermal efficiency and propulsive efficiency. Nonetheless, this situation can cause severe damage to the vane material because of the repeated high thermal loads. Using thermo-mechanical analysis, this paper presents damage scenarios of a nozzle vane's trailing edge (TE) and their impact on flow and heat phenomena, including mechanical behavior of the vane material. As the upstream process, computational fluid dynamics (CFD) simulation with conjugate heat transfer (CHT) is used to numerically investigate flow physics and heat transfer phenomena. Then, for the downstream calculations, a static structure model for a steady temperature analysis is used. The NASA-MARK II vane profile is used to define vane boundaries in the computational domain. Broken vane TE scenarios are presented in both the streamwise and spanwise directions, with a short, shallow cutback expanding into a long, deep one from 0.1 cm x 1 cm to 0.3 cm x 3 cm. The numerical results are mainly presented and discussed in terms of variations in surface and internal temperatures, as well as von Mises equivalent stress and strain. The damaged TE, according to the findings, has a significant impact on the thermo-mechanical variations of the vane material. This emphasizes the severity of a damaged vane TE if the turbine is still operating without maintenance.
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Numerical analysis of airside heat and mass transfer characteristics of fin-and-tube heat exchanger under dehumidifying conditions using VOF method
(2026-01-07)
Boonsuk, Krittawit
;
Wongsatanawarid, Atikorn
;
Ke, Zhaoqing
;
Prapamonthon, Prasert
This paper presents a numerical study of the air-side heat and mass transfer characteristics of a single-row plain fin-and-tube heat exchanger with specific geometrical details under dehumidifying conditions using the volume of fluid (VOF) method with species transport. Moist air, a combination of dry air and water vapor, is used as a working fluid. The Lee model, which is embedded in ANSYS Fluent, is used to implement the phase change model. Without additional source terms defined by user-defined functions, the default value is replaced with mass transfer time relaxation for condensation based on the density of the water liquid phase, the water vapor phase, and mass transfer time relaxation for evaporation. The effects of relative humidity and frontal velocity on heat and mass transfer are presented and discussed. The numerical results in terms of heat and mass transfer-based Colburn factors are validated against those found in the open literatures. The findings indicate that the effect of inlet relative humidity to temperature distribution, flow field and distribution pattern of water vapor mass fraction is small. The air-side heat and mass transfer coefficient are higher while the frontal velocity and inlet relative humidity are higher. The inlet relative humidity has little influence on air-side heat and mass performance when the frontal velocity is low.
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Numerical Study on Flow Physics of Damaged Vane Trailing Edge
(2024-01-01)
Thammachote, B.
;
Premyothin, J.
;
Khumhaeng, S.
;
Tanpradit, D.
;
Dipasquale, D.
According to practical applications in gas turbines, the turbine's nozzle guide vane (NGV) is the first downstream component of the combustor that experiences high thermal loads from burned gases. This situation can severely damage the vane material, particularly the trailing edge (TE). This is because of the limitation of TE thickness and the difficulty of effective cooling in that region. Moreover, the deterioration of the TE surface leads to vane fatalities and has a negative impact on turbine performance because the flow field is unfavorably changed during the operation. This paper aims to numerically study the flow physics of a damaged vane TE using a 3D steady-flow CFD simulation with the SST k-turbulence model. Under the assumptions of ideal gas and compressible flow, air is used as the burned gas. To simplify the vane damage shape, the broken pattern at the TE is given in a long cutback geometry in the simulation. Numerical results in terms of turbulent kinetic energy (TKE), vorticity magnitude, turbulent viscosity, and streamlines are compared and discussed. The interesting findings show that with the inclusion of the damaged TE, the TKE and turbulent viscosity in the broken region increase dramatically on both the midspan and vertical planes. Furthermore, an increment in the vortex size is observed on the midspan plane. However, the vortex centers along the broken region disappear and are replaced by smooth streamlines.
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Extra-low Reynolds number vane separation using immersed boundary method
(2019-01-01)
Prapamonthon, Prasert
;
Yin, Bo
;
Yang, Guowei
Nowadays, mini unmanned aerial vehicles (MUAVs) and micro air vehicles (MAVs) are not only beneficially used as aviation models but also as modern drones for military missions and other civilian applications. Hence, research and development of propulsion sources for MUAVs and MAVs dynamically increase with a future trend of high performance, but low energy consumption. Certainly, using micro and ultra-small-size gas turbine is a good option for the propulsion source. To achieve ideal flight of MUAVs and MAVs powered by micro and ultra-small-size gas turbines under this trend, understanding of flow phenomena at wide ranges of Reynolds number is essential. This research presents a 2D numerical study of characteristics of laminar flow separation and the trailing-edge vortex on a turbine vane at extra-low Reynolds numbers (Res) i.e. Re = 1800 and 3600, and three rotational angles (a) i.e. a = 0º, 15º and 30º using immersed boundary method (IBM). With this method, the problem of incompressible flow is addressed by a sharp interface IBM. Numerical results indicate that IBM can characterize phenomena of laminar separation flow, which usually happens on the turbine airfoil when laminar boundary layer cannot overcome adverse pressure gradients and viscous effects. To our current knowledge, this may be the first research to study flow behavior at such low Res for gas turbine vanes using IBM. Even though it is now not common to operate micro and ultra-small-size gas turbines under these conditions, it is important to know how aerodynamic performance may be if micro and ultra-small-size gas turbines need to run under such conditions in the near future.
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Numerical Solutions of Transonic to Supersonic Flow over Backward-Forward Facing Step with Heat Flux Conditions
(2026-03-06)
Jeatrakul, Karn
;
Prapamonthon, Prasert
;
Tanpradit, Ditthaphat
;
Wongsatanawarid, Atikorn
;
Hao, Zhanzhou
Flows phenomena over a backward-facing step (BFS) and a forward-facing step (FFS) are critical for understanding flow physics in engine, aerodynamic, heat transfer systems. Given the rapid advancement of high-speed technology, the presence of shock waves and aerodynamic heat can have an impact on flow physics, thereby emphasizing the importance of high-speed flow over BFS and FFS with heat transfer. This paper presents numerical solutions of steady two-dimensional viscous turbulent flow over a continuous backward-forward facing step (BFFS) in the transonic to supersonic regime with heat flux conditions using STAR-CCM+. The compressible air and k-ϵ turbulence model are used for the simulations. The effects of inlet Mach numbers ranging from 0.8 to 3.0 and bottom step heat fluxes varying from 0.5 to 10.0 kW/m2 on flow physics are investigated. Numerical results depict flow phenomena such as flow separation, recirculation, and shock wave, as well as thermal distribution. Furthermore, the results show that variations in the inlet Mach number affect flow behaviors, while higher heat fluxes cause dramatical changes in Nusselt number, especially, in the BFS corner for transonic flow.
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Parametric study on wing-lambda-shock formation
(2021-01-01)
Chainok, Sirikorn
;
Rungroch, Thanapol
;
Chairach, Pattarasuda
;
Prapamonthon, Prasert
;
Yooyen, Soemsak
It is well-known that a wing is one of the most important parts of an aircraft as it is used to generate lift force. According to a wing moving at sufficiently high subsonic speeds, the flow speed on the wing's upper surface can be supersonic due to acceleration through the curvature-created suction, thereby forming a shock wave in a lambda shape. Additionally, the lambda shock can interact with the boundary layer flow. These phenomena relate to disturbances in the flow field, including flow separation, thus causing undesirable effects on lift production. Hence, a better understanding of the phenomenon of wing-lambda-shock formation and its nature is essential. This study presents a numerical investigation of the lambda-shock formation on an ONERA M6 wing, which is known as a swept, semi-span wing with no twist, under parametric effects of angleof-attack, and free-stream Mach number, which is increased up to the supersonic regime. The pressure coefficients obtained by simulations are validated by open data. Then, numerical results in terms of the local pressure coefficient, local Mach number, averaged lift and drag coefficients, and?-shape characteristics based on Mach number and pressure coefficients are discussed under an investigated range of the parameters. Results show that the angle-of-attack and free-stream Mach number can affect the lambda shock formation on the wing upper surface physically. Specifically, an iso-sonic surface with lambda shock waves is disturbed when the angle-of-attack and free-stream Mach number vary in an investigated range. This also affects lift and drag coefficients of the wing.

Prapamonthon, Prasert

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