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 - 5 of 5

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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 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 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/m<sup>2</sup> 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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Numerical Solutions of Heat Convection Problems in Film Cooling Flow Over Adiabatic and Diabatic Flat Plates
(2026-03-06)
Jeatrakul, Karn
;
Prapamonthon, Prasert
;
Wongsatanawarid, Atikorn
;
Wang, Yeteng
;
Hao, Zhanzhou
This paper presents numerical solutions for film cooling flow over a flat plate subjected to heat convection problems, namely (1) adiabatic, and (2) diabatic plates with constant heat fluxes of 500 and 1000 W/m<sup>2</sup>. The governing equations and realizable k-ε turbulence model are solved to provide numerical solutions in terms of film effectiveness for the adiabatic case, and dimensionless temperature and Nusselt number for the diabatic case. Numerical solutions are carried out at two film hole angles i.e. α = 25° and 35° and two blowing ratios i.e. BR = 0.3 and 0.6. The numerical solutions indicate that the smaller angle and lower blowing ratio can provide better effective cooling on the flat plate for both problem conditions. In addition, the strong influence of the blowing ratio on the film cooling flow is observed. When the heat flux is included, the Nusselt number increases in spanwise and streamwise direction with the heat flux.
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Effects of commercial fin patterns to air-side performance of outdoor air unit (OAU) for operating room during dehumidification in tropical region
(2026-01-07)
Boonsuk, Krittawit
;
Wongsatanawarid, Atikorn
;
Prapamonthon, Prasert
The design of the outdoor air unit (OAU) for the operating room is always challenging in tropical countries where they should be operated in a wide range of humidity. In this study, the design of the cooling coil for the outdoor air unit has performed with its performance to satisfy the national and international guidelines. The geometrical details of each component and the air-side performance of the OAU main cooling coil are obtained from calculation results performed in commercial software and then validated with experimental results. The validation results show that they are in good agreement for total cooling capacity and sensible cooling capacity within the bound of error of ±7.5% and ±10.0% respectively. Therefore, the condensation rate data validation results show a wider band of error of ±15.0% to cover all experimental results especially for the condensation rate higher that 6 kg/hr. The effects of five different fin patterns on the air-side performance of the OAU main cooling coil are investigated. Based on the determined conditions, the pyramid fin pattern provides the highest total cooling capacity with slightly higher than the corrugated fin. Louvred fin pattern performs the highest sensible cooling capacity and the highest sensible heat ratio among five fin patterns, and pyramids give the lowest. For the condensation rate, the pyramid fin pattern demonstrates the highest value among the rest but slightly higher than the smooth fin. The obtained result from this study is interesting that the pyramid fin pattern demonstrates the highest performance in dehumidifying application.

Prapamonthon, Prasert

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