Numerical Simulation of a Particle-Laden Impinging Jet: Effect of Wall Curvature on Particle Deposition

2017 ◽  
Author(s):  
Giuliano Agati ◽  
Domenico Borello ◽  
Franco Rispoli ◽  
Alessandro Salvagni ◽  
Paolo Venturini
Keyword(s):  
Numerical Simulation ◽  
Particle Motion ◽  
Particle Deposition ◽  
Turbine Blades ◽  
Jet Impingement ◽  
Impinging Jet ◽  
Industrial Applications ◽  
Surface Curvature ◽  
Internal Cooling ◽  
Orthogonal Direction

Jet impingement against surfaces is uses in several industrial applications, including the internal cooling of turbine blades. Coolant used for blade cooling is air bleed from a compressor and is laden with particles. A numerical simulation of a particle-laden impinging jet is here proposed, aiming at studying and analysing the effect of surface curvature on flow field, particle motion and deposit formation. To this aim, an impinging jet on a flat and a curved walls is considered. Flow motion is be solved using Direct Numerical Simulation, thus no additional model is needed for turbulence effect on particle motion. Results show that the deposit patterns follow some secondary flow structures, showing a series of peaks forming according to those structures. The peaks are present in both the main orthogonal direction of the jet, but they are not symmetrical due to surface curvature.

Impinging Jet Cooled Plate Fin Heat Sinks With Turbulators Enhancement

2009 ◽  
Author(s):  
Ganesh Subbuswamy ◽  
Xianchang Li
Keyword(s):  
Heat Transfer ◽  
Reynolds Number ◽  
Heat Sink ◽  
Numerical Study ◽  
Turbine Blades ◽  
Jet Impingement ◽  
Impinging Jet ◽  
Impinging Jets ◽  
Heat Sinks ◽  
Internal Cooling

Extended surfaces (fins) and impinging jets have been used to enhance heat transfer in many applications. In electronic thermal management, heat sinks can be designed to take advantage of the combined effect of fins and jet impingement such as jets impinging on an array of pin fins or plate fins. Significant studies have been focused on the thermal resistance, pressure drop, and the parametric effect of Reynolds number, fin thickness, density, and height. To further improve the heat sink performance, ribs/turbulators, which are widely employed in internal cooling of gas turbine blades, can be integrated into the plate fins, especially close to the surface area with low heat transfer coefficient. Numerical study is performed in this paper to examine the flow and heat transfer behavior of plate fin heat sinks cooled by an impinging jet and enhanced by the ribs. The height and shape of the turbulators are investigated to achieve the best performance. Parametric studies also include the flow Reynolds number and the spacing between the ribs. Heat transfer mechanism is explored for the confined turbulence jet with and without turbulators. It is expected that the rib enhancement can lead to a more cost-effective heat sink for cooling of electronic components. Further enhancement and optimization are discussed in this paper.

Numerical Simulation Study of Impinging Jet Impact Fin Surface on Heat Transfer Characteristics

2013 ◽  
Vol 663 ◽  
pp. 586-591 ◽  
Author(s):  
Li Ming Zhou ◽  
Lei Zhu ◽  
Jing Quan Zhao ◽  
Meng Zheng
Keyword(s):  
Heat Transfer ◽  
Numerical Simulation ◽  
Thermal Resistance ◽  
Jet Impingement ◽  
Impinging Jet ◽  
Heat Transfer Characteristics ◽  
Transfer Coefficients ◽  
Transfer Characteristics ◽  
Jet Impact ◽  
Jet Array

Three-dimensional numerical simulation was implemented to analyze the heat transfer characteristics for jet impingement impact fin surface. 60 calculation cases were simulated to investigate the effects of different fin surfaces on heat transfer characteristics, and 12 jet array impingement cases were calculated for comparison. The results shown that the fin shape, the height and the fin arrangement were the critical factors to affect the jet impingement and the best combination were existed in a certain range. The thermal resistance of cylinder fin arranged in order was34.7 percent higher than that of cylinder fin arranged staggered. The thermal resistance of square fin arranged in order was38.9 percent higher than that of square fin arranged staggered .The heat transfer coefficients of impinging jet impact fin surface were better than that of jet array impingement. The fitting correlations on heat transfer of impinging jet impact fin surface were given.

Experimental and Numerical Study of Jet Impingement Cooling for Improved Gas Turbine Blade Internal Cooling With In-Line and Staggered Nozzle Arrays

2020 ◽  
Vol 143 (1) ◽  
Author(s):  
Abdel Rahman Salem ◽  
Farah Nazifa Nourin ◽  
Mohammed Abousabae ◽  
Ryoichi S. Amano
Keyword(s):  
Heat Transfer ◽  
Nusselt Number ◽  
Gas Turbine ◽  
Numerical Study ◽  
Turbine Blades ◽  
Jet Impingement ◽  
Target Surface ◽  
Internal Cooling ◽  
Impingement Cooling ◽  
Gas Turbine Blades

Abstract Internal cooling of gas turbine blades is performed with the combination of impingement cooling and serpentine channels. Besides gas turbine blades, the other turbine components such as turbine guide vanes, rotor disks, and combustor wall can be cooled using jet impingement cooling. This study is focused on jet impingement cooling, in order to optimize the coolant flow, and provide the maximum amount of cooling using the minimum amount of coolant. The study compares between different nozzle configurations (in-line and staggered), two different Reynold's numbers (1500 and 2000), and different stand-off distances (Z/D) both experimentally and numerically. The Z/D considered are 3, 5, and 8. In jet impingement cooling, the jet of fluid strikes perpendicular to the target surface to be cooled with high velocity to dissipate the heat. The target surface is heated up by a direct current (DC) power source. The experimental results are obtained by means of thermal image processing of the captured infra-red (IR) thermal images of the target surface. Computational fluid dynamics (CFD) analysis were employed to predict the complex heat transfer and flow phenomena, primarily the line-averaged and area-averaged Nusselt number and the cross-flow effects. In the current investigation, the flow is confined along with the nozzle plate and two parallel surfaces forming a bi-directional channel (bi-directional exit). The results show a comparison between heat transfer enhancement with in-line and staggered nozzle arrays. It is observed that the peaks of the line-averaged Nusselt number (Nu) become less as the stand-off distance (Z/D) increases. It is also observed that the fluctuations in the stagnation heat transfer are caused by the impingement of the primary vortices originating from the jet nozzle exit.

Numerical Simulation of Two Pass Gas Turbine Blade Internal Cooling Channels With 90 Degree Varying Height Ribs

2012 ◽  
Author(s):  
Sourabh Kumar ◽  
R. S. Amano
Keyword(s):  
Heat Transfer ◽  
Numerical Simulation ◽  
Gas Turbine ◽  
Thermal Stresses ◽  
Turbine Blades ◽  
Simulation Software ◽  
Inlet Temperature ◽  
Internal Cooling ◽  
Ribbed Channel ◽  
Smooth Channel

Improvement in thermal efficiency of gas turbine can be obtained by operating it at high inlet temperatures. In addition to improving the performance, the cons of high inlet temperature is high thermal stresses on the turbine blades. To improve life and performance of the blade, improved cooling technologies are desired. The main objective of this paper is to perform computational analysis of the ribs with varying height and compare this with 90 degree ribbed channel and smooth channels. The numerical analysis is carried out using ANSYS-Fluent, a flow modeling simulation software. The flow is assumed to be steady state and flow turbulence is modeled using the k-ε with Standard Wall Functions. Local heat transfer and friction loss in a square duct roughened with 90 degree ribs with varying height is investigated for different Reynolds number. The pitch of the rib is considered to be 10 times the height of rib which is 0.0635 m. The square cross section of the channel is .0508x .0508 m2. The pitch of rib to rib height ratio varies from 10 to 20 at the center of the channel. There is a rib considered at the turn section as well. The numerical simulation produced higher heat transfer for the varying height ribs as compared to 90 degree ribbed channel and smooth channel.

scholarly journals Effect of Rotation Number on Heat Transfer Characteristics of a Row of Impinging Jets in Confined Channel

2020 ◽  
Vol 77 (1) ◽  
pp. 161-171
Author(s):  
Thantup Nontula ◽  
Natthaporn Kaewchoothong ◽  
Wacharin Kaew-apichai ◽  
Chayut Nuntadusit
Keyword(s):  
Heat Transfer ◽  
Nusselt Number ◽  
Rotation Number ◽  
Turbine Blades ◽  
Jet Impingement ◽  
Impinging Jets ◽  
Internal Cooling ◽  
Heat Transfer Characteristics ◽  
Transfer Characteristics ◽  
Impingement Surface

Jet impingement has been applied for internal cooling in gas turbine blades. In this study, heat transfer characteristics of impinging jets from a row of circular orifices were investigated inside a flow channel with rotations. The Reynolds number (Re) based on the jet mean velocity was fixed at 6,700. Whereas, the rotation number (Ro) of a channel was varied from 0 to 0.0099. The jet-to-impingement distance ratio (L/Dj) and jet pitch ratio (P/Dj) were respective 2 and 4, Dj is a jet diameter of 5 mm. The thermochromic liquid crystals (TLCs) technique was used to measure the heat transfer coefficient distributions on an impingement surface. The results show that heat transfer enhancement on a jet impingement surface depended on the effects of crossflow and Coriolis force. The local Nusselt number at X/Dj?20 on the leading side (LS) was higher than on the trailing side (TS) while heat transfer on the LS at 20?X/Dj?40 gained the lowest, compared to on the TS. The average Nusselt number ratios ( ) on the TS at Ro = 0.0049 gave higher than on the LS of around 2.17%. On the other hand, the on the TS at Ro = 0.0099 was less than the LS of about 0.08%.

Numerical Study on Particles Deposition in the U-bend Ribbed Passage

2020 ◽  
Vol 143 (2) ◽  
Author(s):  
Lin Li ◽  
Cun-liang Liu ◽  
Bing-ran Li ◽  
Hui-ren Zhu ◽  
Zhuang Wu ◽  
...  
Keyword(s):  
Particle Deposition ◽  
Numerical Study ◽  
Turbine Blades ◽  
Reynolds Numbers ◽  
Navier Stokes ◽  
Internal Cooling ◽  
Cfd Simulations ◽  
Cooling Effectiveness ◽  
Phase Calculation ◽  
Discrete Phase

Abstract The accumulation of particles in the internal cooling channel reduces the cooling effectiveness of the turbine blades and even affects the safe operation of the aero engine. Discrete phase-CFD simulations of particles deposition were performed in the U-bend ribbed passage by applying Euler–Lagrange method. Reynolds Average Navier–Stokes method was used for the gas phase calculation. The realizable k–ε turbulence model and enhanced wall treatment were adopted. The discrete phase was solved by using Lagrangian with random walk model. A particle deposition model was implemented by using user-defined functions. The Reynolds numbers of 30,000, 23,000, and 15,500 were studied. Particles diameters in the range 1–20 μm were considered. The particles deposition distribution of different locations is obtained in this study, and the influence of the Reynolds numbers and particle diameters on particles deposition performance are analyzed. Results show that the first row of ribs has a protective effect on the back row of ribs. The increased Reynolds number and increased particles diameter promote the deposition of particles on the wall.

Review of Gas Turbine Internal Cooling Improvement Technology

2020 ◽  
Vol 143 (8) ◽  
Author(s):  
Farah Nazifa Nourin ◽  
Ryoichi S. Amano
Keyword(s):  
Gas Turbine ◽  
Turbine Blade ◽  
Cooling System ◽  
Guide Vane ◽  
Turbine Blades ◽  
Jet Impingement ◽  
Internal Cooling ◽  
Gas Turbine Blade ◽  
Pin Fins ◽  
Rib Turbulators

Abstract The higher firing temperature reflects the higher efficiency of the gas turbine. However, using higher temperatures is limited as it may cause a rupture, bending, or failure of the turbine blades. Hence, the development of an effective internal cooling system of the gas turbine blade is essential. At the same time, it is necessary to ensure the lowest possible penalty on the thermodynamics performance cycle. Researchers are working over the years to find out the efficient cooling channel design with high transfer while the lowest pressure drop. They ran several cases both numerically and experimentally. This paper reviews the published research in the various methods of gas turbine internal cooling, such as using rib turbulators, dimples, jet impingement, pin fins, and guide vane, of the gas turbine blade.

Numerical Investigation on Sand Particles Deposition in a U-Bend Ribbed Internal Cooling Passage of Turbine Blade

2019 ◽  
Author(s):  
Lin Li ◽  
Cun-liang Liu ◽  
Xiao-Yu Shi ◽  
Hui-ren Zhu ◽  
Bing-ran Li
Keyword(s):  
Reynolds Number ◽  
Turbine Blade ◽  
Particle Deposition ◽  
Flow Direction ◽  
Turbine Blades ◽  
Deposition Flux ◽  
Internal Cooling ◽  
Sand Particles ◽  
Cooling Passage ◽  
Internal Cooling Passage

Abstract Sand particles impinge the internal cooling passage of the turbine blade and easily deposit, which lead to the decrease of cooling efficiency of the turbine blade and the increase of turbine blade temperature. In order to explore sand particles deposition mechanism in the internal cooling passage of turbine blades, the numerical simulation was performed in a U-bend passage with rib turbulators by means of a commercial CFD code. The fluid phase was modelled employing Reynolds-averaged Navier-Stokes approach. The discrete phase was solved using Lagrangian particle tracking method and a continuous random walk model. A particle deposition model was implemented using user-defined functions. The Reynolds numbers of 30000, 23000 and 15500 are considered. Particles sizes in the range 1–20 microns are considered. Results show that the particles deposition flux decreases gradually along the flow direction. The particles significantly deposit on the rib wall and the bend wall, especially on the windward rib wall and the upstream wall of the bend, with less deposition on the leeward rib wall. This is because the rib wall hinders the movement of fluid and sand particles impact the wall due to inertia, which lead to the energy loss. The particles deposition flux on the windward rib wall increases with the increase of Reynolds number and particles diameter, while the deposition flux on the leeward rib wall decreases. With the increase of the particles diameter, the particles deposition flux increases. The deposition rate increases with the increase of Reynolds number and particles diameter.

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