An Experimental and Numerical Investigation of the Effect of Combustor-Nozzle Platform Misalignment on Endwall Heat Transfer at Transonic High Turbulence Conditions

2016 ◽  
Author(s):  
A. Arisi ◽  
D. Mayo ◽  
Z. Li ◽  
W. F. Ng ◽  
H. K. Moon ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Numerical Study ◽  
Horseshoe Vortex ◽  
Aerodynamic Characteristics ◽  
Secondary Flows ◽  
Navier Stokes ◽  
Vortex System ◽  
Ansys Fluent ◽  
Heat Transfer Augmentation ◽  
Exit Mach Number

A detailed experimental and numerical study has been conducted to investigate the endwall heat transfer characteristics on a nozzle platform that has been misaligned with the combustor exit, resulting in a backward facing step at the nozzle inlet. The study was carried out under transonic engine representative conditions with an exit Mach number of 0.85 (Reexit = 1.5 × 106), and an inlet turbulence intensity of 16%. A transient infrared thermography technique coupled with endwall static pressure ports, were used to map the endwall surface heat transfer and aerodynamic characteristics respectively. A numerical study was also conducted by solving the steady state Reynolds Averaged Navier Stokes (RANS) equations using the commercial CFD solver ANSYS Fluent v.15. The numerical results were then validated by comparing to experiment data and good agreement was observed. The results reveal that the classical endwall secondary flows (endwall crossflows, horseshoe and passage vortices) are weakened and a unique auxiliary vortex system develops within the passage and interacts with the weakened horseshoe vortex. It is observed that heat transfer in the first half of the passage endwall is heavily influenced by this auxiliary vortex system. Heat transfer augmentation of between 15% and 40% was also observed throughout the NGV endwall. Furthermore, the auxiliary vortex system results in a delayed cross-passage migration of the horseshoe vortex which consequently results in large lateral gradient in heat transfer downstream of the throat.

scholarly journals Comparison of Visualized Turbine Endwall Secondary Flows and Measured Heat Transfer Patterns

1984 ◽  
Vol 106 (1) ◽  
pp. 168-172 ◽  
Author(s):  
R. E. Gaugler ◽  
L. M. Russell
Keyword(s):  
Heat Transfer ◽  
Large Scale ◽  
Horseshoe Vortex ◽  
Secondary Flows ◽  
Turbine Vane ◽  
A New Technique ◽  
Exit Mach Number ◽  
Visualization Techniques ◽  
Neutrally Buoyant ◽  
First Time

Various flow visualization techniques were used to define the secondary flows near the endwall in a large scale turbine vane cascade. The cascade was scaled up from one used to generate endwall heat transfer data under a joint NASA-USAF contract. A comparison of the visualized flow patterns and the measured Stanton number distributions was made for cases where the inlet Reynolds number and exit Mach number were matched. Flows were visualized by using neutrally buoyant helium-filled soap bubbles, by using smoke from oil soaked cigars, and by a new technique using permanent marker pen ink dots and synthetic wintergreen oil. For the first time, details of the horseshoe vortex and secondary flows can be directly compared with heat transfer distributions. Near the cascade entrance, there is an obvious correlation between the two sets of data, but well into the passage the effect of secondary flow is not as obvious.

An Experimental Study Heat Transfer in a Large-Scale Turbine Rotor Passage

1994 ◽  
Vol 116 (1) ◽  
pp. 1-13 ◽  
Author(s):  
M. F. Blair
Keyword(s):  
Heat Transfer ◽  
Experimental Study ◽  
Large Scale ◽  
Leading Edge ◽  
Horseshoe Vortex ◽  
Turbine Rotor ◽  
Secondary Flows ◽  
Vortex System ◽  
Tip Leakage ◽  
High Heat Transfer

An experimental study of the heat transfer distribution in a turbine rotor passage was conducted in a large-scale, ambient temperature, rotating turbine model. Heat transfer was measured for both the full-span suction and pressure surfaces of the airfoil and for the hub endwall surface. The objective of this program was to document the effects of flow three dimensionality on the heat transfer in a rotating blade row (versus a stationary cascade). Of particular interest were the effects of the hub and tip secondary flows, tip leakage, and the leading-edge horseshoe vortex system. The effect of surface roughness on the passage heat transfer was also investigated. Midspan results are compared with both smooth-wall and rough-wall finite-difference two-dimensional heat transfer predictions. Contour maps of Stanton number for both the rotor airfoil and endwall surfaces revealed numerous regions of high heat transfer produced by the three-dimensional flows within the rotor passage. Of particular importance are regions of local enhancement (as much as 100 percent over midspan values) produced on the airfoil suction surface by the secondary flows and tip-leakage vortices and on the hub endwall by the leading edge horseshoe vortex system.

scholarly journals Numerical study of the aerodynamic characteristics of an axisymmetric profile of an optimized shape

2021 ◽  
pp. 5-11
Keyword(s):  
Gas Flow ◽  
Aerodynamic Drag ◽  
Numerical Study ◽  
Aerodynamic Characteristics ◽  
Navier Stokes ◽  
Ansys Fluent ◽  
Inviscid Gas ◽  
Speed Up ◽  
The Cost ◽  
Different Characteristics

Today, one of the important and urgent tasks of the aerodynamics science is the study and op-timization of aerodynamic characteristics of optimized profile shapes in a gas flow. This problem arises in the design of aircraft and various vessels and is associated with a rational choice of profile shape for a large number of different characteristics and, in particular, in terms of aerodynamic drag. In this paper, consider methods for optimizing an axisymmetric aerodynamic profile in a sta-tionary laminar inviscid gas flow at different angles of attack. The proposed method of solv-ing such a problem of optimization and numerical study of aerodynamic characteristics of the described body in the flow is relevant due to the complexity of its solution, for example, by traditional methods based on the Navier-Stokes system of differential equations. Experi-mental methods are based on expensive and time-consuming tools that do not guarantee find-ing the optimum. Such a computing tool as Ansys Fluent is well suited for solving such prob-lems of hydroaerodynamics and allows not only to speed up and reduce the cost of the compu-tational experiment, but also to increase the efficiency of its implementation. The article describes the process of finding the optimum, which reduces to minimizing the drag force of the previously described axisymmetric profile. A description is also given of the wing

An Investigation of the Effect of interrupted fin arrangements on the Thermal Performance of a Heat Sink under a Free Convection Condition

2019 ◽  
Vol 7 (1) ◽  
pp. 43-53
Author(s):  
Abbas Jassem Jubear ◽  
Ali Hameed Abd
Keyword(s):  
Heat Transfer ◽  
Steady State ◽  
Natural Convection ◽  
Thermal Performance ◽  
Heat Sink ◽  
Numerical Study ◽  
Ansys Fluent ◽  
Fluent Software ◽  
Steady State Heat ◽  
Steady State Heat Transfer

The heat sink with vertically rectangular interrupted fins was investigated numerically in a natural convection field, with steady-state heat transfer. A numerical study has been conducted using ANSYS Fluent software (R16.1) in order to develop a 3-D numerical model.  The dimensions of the fins are (305 mm length, 100 mm width, 17 mm height, and 9.5 mm space between fins. The number of fins used on the surface is eight. In this study, the heat input was used as follows: 20, 40, 60, 80, 100, and 120 watts. This study focused on interrupted rectangular fins with a different arrangement and angle of the fins. Results show that the addition of interruption in fins in various arrangements will improve the thermal performance of the heat sink, and through the results, a better interruption rate as an equation can be obtained.

Numerical study of the aerodynamic and power characteristics of the cycloidal rotor, under incoming flow

2019 ◽  
pp. 25-34
Author(s):  
Александр Анатольевич Дектерев ◽  
Артем Александрович Дектерев ◽  
Юрий Николаевич Горюнов
Keyword(s):  
Flow Velocity ◽  
Numerical Study ◽  
Lift Coefficient ◽  
Simulation Method ◽  
Aerodynamic Characteristics ◽  
Incoming Flow ◽  
Ansys Fluent ◽  
Energy Characteristics ◽  
Power Characteristics ◽  
Calculation Results

Исследование направлено на разработку и апробацию методики численного моделирования аэродинамических и энергетических характеристик циклоидального ротора. За основу взята конфигурация ротора IAT21 L3. Для нее с использованием CFD-пакета ANSYS Fluent построена математическая модель и выполнен расчет. Проанализировано влияние скорости набегающего потока воздуха на движущийся ротор. Математическая модель и полученные результаты исследования могут быть использованы при создании летательных аппаратов с движителями роторного типа. This article addresses the study of the aerodynamic and energy characteristics of a cycloidal rotor subject to the influence of the incoming flow. Cycloidal rotor is one of the perspective devices that provide movement of aircrafts. Despite the fact that the concept of a cycloidal rotor arose in the early twentieth century, the model of a full-scale aircraft has not been yet realized. Foreign scientists have developed models of aircraft ranging in weight from 0.06 to 100 kg. The method of numerical calculation of the cycloidal rotor from the article [1] is considered and realized in this study. The purpose of study was the development and testing of a numerical simulation method for the cycloidal rotor and study aerodynamic and energy characteristics of the rotor in the hovering mode and under the influence of the oncoming flow. The aerodynamic and energy characteristics of the cycloidal rotor, rotating at a speed of 1000 rpm with incoming flow on it with velocities of 20-80 km/h, were calculated. The calculation results showed a directly proportional increase of thrust with an increase of the incoming on the rotor flow velocity, but the power consumed by the rotor was also increased. Increase of the incoming flow velocity leads to the proportional increasing of the lift coefficient and the coefficient of drag. Up to a speed of 80 km/h, an increase in thrust and power is observed; at higher speeds, there is a predominance of nonstationary effects and difficulties in estimating the aerodynamic characteristics of the rotor. In the future, it is planned to consider the 3D formulation of the problem combined with possibility of the flow coming from other sides.

Numerical Study on Control of Sunroof Buffeting

2021 ◽  
Vol 13 (2) ◽  
Author(s):  
K. Vijaykumar ◽  
S. Poonkodi ◽  
A.T. Sriram
Keyword(s):  
Numerical Study ◽  
Leading Edge ◽  
Dominant Frequency ◽  
Navier Stokes ◽  
Navier Stokes Equation ◽  
Ansys Fluent ◽  
Flow Modification ◽  
Numerical Result ◽  
Modification Technique ◽  
Commercial Solver

Sunroof has become one of the essential features of a luxury car, and it provides natural air circulation and good illumination into the car. But the primary problem associated with it is the buffeting noise which causes discomfort to the passengers. Though adequate studies were carried out on sunroof buffeting, efficient control techniques are needed to be developed from fundamental mechanism. To reduce the buffeting noise, flow modifications at the entrance of the sunroof is considered in this study. The internal portion of the car with sunroof is simplified into a shear driven open cavity, and two-dimensional numerical simulations are carried out using commercial solver, ANSYS Fluent. Reynolds averaged Navier-Stokes equation is used with the realizable k-? turbulence model. The unsteady numerical result obtained in this study is validated with the available experimental results for the dominant frequency. The prediction is good agreement with experiment. Flow modification technique is proposed to control the sunroof buffeting by implementing geometric modifications. A hump has been placed near the leading edge of the cavity which resulted in significant reduction of pressure oscillations. Parametric studies have been performed by varying the height of hump and the distance of hump from the leading edge. There is no prominent difference when the height of the hump is varied. As the distance of the hump from the leading edge is reduced, the sound pressure level decreases.

A Numerical Study of Turbulent Boundary Layer Flow Over a Flat Surface With a Single Dimple

2000 ◽  
Author(s):  
Mark E. Kithcart ◽  
David E. Klett
Keyword(s):  
Heat Transfer ◽  
Boundary Layer ◽  
Turbulent Boundary Layer ◽  
Boundary Layer Flow ◽  
Flat Surface ◽  
Numerical Study ◽  
Heat Transfer Augmentation ◽  
Study Results ◽  
Turbulent Boundary Layer Flow ◽  
Layer Flow

Abstract Turbulent boundary layer flow over a flat surface with a single dimple has been investigated numerically using the FLUENT CFD software package, and compared to an experiment by Ezerskii and Shekhov [1989], which studied the same configuration. The impetus for this work developed as a result of previous studies. Kithcart and Klett [1996], and Afanas’yev and Chudnovskiy [1992], showed that dimpled surfaces enhance heat transfer comparably to surfaces with protrusion roughness elements, but with a much lower drag penalty. However, the actual physical mechanisms involved in this phenomena were only partially known prior this study. Results obtained numerically are in good agreement with the experiment, most notably the confirmation of the existence of a region of enhanced heat transfer created by interaction of the flow with the dimple. In particular, the simulation indicates that heat transfer augmentation is a consequence of the development of a stagnation flow region within the dimple geometry, and the existence of coherent vortical structures which create a periodic flow-field within and immediately downstream of the dimple. This periodicity appears to govern the magnitude of the heat transfer augmentation.

Conjugate Free Convection Heat Transfer and Thermodynamic Analysis of Infrared Suppression Device with Cylindrical Funnels

2022 ◽  
Author(s):  
Vikrant Chandrakar ◽  
Arnab Mukherjee ◽  
Jnana Ranjan Senapati ◽  
Ashok Kumar Barik
Keyword(s):  
Heat Transfer ◽  
Entropy Generation ◽  
Convection Heat Transfer ◽  
Navier Stokes ◽  
Bejan Number ◽  
Navier Stokes Equation ◽  
Ansys Fluent ◽  
Geometric Ratio ◽  
Flow Rate Increase ◽  
Free Convection Heat

Abstract A convection system can be designed as an energy-efficient one by making a considerable reduction in exergy losses. In this context, entropy generation analysis is performed on the infrared suppression system numerically. In addition, results due to heat transfer are also shown. The numerical solution of the Navier-stokes equation, energy equation, and turbulence equation is executed using ANSYS Fluent 15.0. To perform the numerical analysis, different parameters such as the number of funnels, Rayleigh number (Ra), inner surface temperature, and geometric ratio are varied in the practical range. Results are shown in terms of heat transfer, entropy generation, irreversibility (due to heat transfer and fluid friction), and Bejan number with some relevant parameters. Streamlines and temperature contours are also provided for better visualization of temperature and flow field around the device. Results show that heat transfer and mass flow rate increase with the increase in Ra. Entropy generation and the irreversibility rise with an increase in the number of funnels and geometric ratio. Also, the Bejan number decreases with an increase in Ra and the number of funnels. A cooling time is also obtained using the lumped capacitance method.

Arriving at the Optimum Overlap Ratio for an Elliptical-Bladed Savonius Rotor

2017 ◽  
Author(s):  
Nur Alom ◽  
Ujjwal K. Saha
Keyword(s):  
Numerical Study ◽  
Superior Performance ◽  
Navier Stokes ◽  
Speed Ratio ◽  
Small Scale ◽  
Efficient Manner ◽  
Ansys Fluent ◽  
Savonius Rotor ◽  
Velocity Magnitude ◽  
Overlap Ratio

The Savonius rotor appears to be particularly promising for the small-scale applications because of its design simplicity, good starting ability, and insensitivity to wind directions. There has been a growing interest in recent times to harness wind energy in an efficient manner by developing newer blade profiles of Savonius rotor. The overlap ratio (OR), one of the important geometric parameters, plays a crucial role in the turbine performance. In a recent study, an elliptical blade profile with a sectional cut angle (θ) of 47.5° has demonstrated its superior performance when set at an OR = 0.20. However, this value of OR is ideal for a semicircular profile, and therefore, requires further investigation to arrive at the optimum overlap ratio for the elliptical profile. In view of this, the present study attempts to make a systemic numerical study to arrive at the optimum OR of the elliptical profile having sectional cut angle, θ = 47.5°. The 2D unsteady simulation is carried out around the elliptical profile considering various overlap ratios in the range of 0.0 to 0.30. The continuity, unsteady Reynolds Averaged Navier-Stokes (URANS) equations and two equation eddy viscosity SST (Shear Stress transport) k-ω model are solved by using the commercial finite volume method (FVM) based solver ANSYS Fluent. The torque and power coefficients are calculated as a function of tip speed ratio (TSR) and at rotating conditions. The total pressure, velocity magnitude and turbulence intensity contours are obtained and analyzed to arrive at the intended objective. The numerical simulation demonstrates an improved performance of the elliptical profile at an OR = 0.15.

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