scholarly journals Numerical Investigation of Inlet Thermodynamic Conditions on Solid Fuel Ramjet Performances

2021 ◽  
Vol 2021 ◽  
pp. 1-20
Author(s):  
Weixuan Li ◽  
Dan Zhao ◽  
Xiong Chen ◽  
Liang Zhu ◽  
Siliang Ni
Keyword(s):  
Heat Transfer ◽  
Chemical Reaction ◽  
Solid Fuel ◽  
Swirl Flow ◽  
Navier Stokes ◽  
Inlet Temperature ◽  
Combustion Heat ◽  
Flow Recirculation ◽  
Flow Field Characteristics ◽  
Inlet Conditions

In this work, 2D numerical RANS (Reynolds Average Navier-Stokes) simulations were carried out to investigate the thermodynamic performance of a solid fuel ramjet (SFRJ) with different inlet conditions. This is achieved by using an in-house FORTRAN code to simulate a 2D turbulent, reacting, unsteady flow in the ramjet engine. The inlet conditions are characterized by three key parameters: (1) swirl number ( S N ), (2) mass flow rate ( m ̇ air ), and (3) inlet temperature ( T in ). With the code numerically validated by benchmarking with a number of computed cases, it is applied to perform systematic studies on the turbulent flow recirculation, combustion, and heat transfer characteristics. It is found that increasing S N , m ̇ air , or T in can dramatically enhance the combustion heat release rate, regression rate, and combustor average temperature. Furthermore, the analysis on the chemical reaction intermediate (CO) reveals that the chemical reaction is more sufficient with increased m ̇ air , but S N = 0 . In addition, a secondary vortex is generated at the corner of the backward facing step in the presence of a swirl flow resulting from the instability of the shear layer. Finally, the nonlinear correlations between the heat transfer, combustion characteristics, and flow field characteristics and the corresponding inlet thermodynamic parameters are identified.

Effect of NGV Lean Under Influence of Inlet Temperature Traverse

2013 ◽  
Author(s):  
A. Rahim ◽  
B. Khanal ◽  
L. He ◽  
E. Romero
Keyword(s):  
Heat Transfer ◽  
Computational Study ◽  
Navier Stokes ◽  
Tangential Displacement ◽  
Inlet Temperature ◽  
Heat Transfer Characteristics ◽  
Transfer Characteristics ◽  
Inlet Conditions ◽  
Hot Streak ◽  
The Impact

One of the most widely studied parameters in turbine blade shaping is blade lean, i.e. the tangential displacement of spanwise sections. However, there is a lack of published research that investigates the effect of blade lean under non-uniform temperature conditions (commonly referred to as a ‘hot-streak’) that are present at the combustor exit. Of particular interest is the impact of such an inflow temperature profile on heat transfer when the NGV blades are shaped. In the present work a computational study has been carried out for a transonic turbine stage using an efficient unsteady Navier-Stokes solver (HYDRA). The configurations with a nominal vane and a compound leaned vane under uniform and hot-streak inlet conditions are analysed. After confirming the typical NGV loading and aero-loss redistributions as seen in previous literature on blade lean, the focus has been directed to the rotor aerothermal behavior. Whilst the overall stage efficiencies for the configurations are largely comparable, the results show strikingly different rotor heat transfer characteristics. For a uniform inlet, a leaned NGV has a detrimental effect on the rotor heat transfer. However, once the hot-streak is introduced, the trend is reversed; the leaned NGV leads to favourable heat transfer characteristics in general and for the rotor tip region in particular. The possible causal links for the observed aerothermal features are discussed. The present findings also highlight the significance of evaluating NGV shaping designs under properly conditioned inflow profiles, rather than extrapolating the wisdom derived from uniform inlet cases. The results also underline the importance of including rotor heat transfer and coolability during the NGV design process.

Uncertainty Analysis of Heat Transfer Predictions Using Statistically Modeled Data From a Cooled 1-1/2 Stage High-Pressure Transonic Turbine

2013 ◽  
Vol 136 (6) ◽  
Author(s):  
Harika S. Kahveci ◽  
Kevin R. Kirtley
Keyword(s):  
Heat Transfer ◽  
Surface Roughness ◽  
High Pressure ◽  
Wall Temperature ◽  
Temperature Measurements ◽  
Navier Stokes ◽  
Inlet Temperature ◽  
Statistical Representation ◽  
Computational Fluid Dynamics Analysis ◽  
Transonic Turbine

This paper compares predictions from a 3D Reynolds-averaged Navier–Stokes code and a statistical representation of measurements from a cooled 1-1/2 stage high-pressure transonic turbine to quantify predictive process sensitivity. A multivariable regression technique was applied to both the inlet temperature measurements obtained at the inlet rake, the wall temperature, and heat transfer measurements obtained via heat-flux gauges on the blade airfoil surfaces. By using the statistically modeled temperature profiles to generate the inlet boundary conditions for the computational fluid dynamics analysis, the sensitivity of blade heat transfer predictions due to the variation in the inlet temperature profile and uncertainty in wall temperature measurements and surface roughness is calculated. All predictions are performed with and without cooling. Heat transfer predictions match reasonably well with the statistical representation of the data, both with and without cooling. Predictive precision for this study is driven primarily by inlet profile uncertainty followed by surface roughness and gauge position uncertainty.

scholarly journals Heat transfer and pressure drop evaluation of different triangular baffle placement angles in cross-corrugated triangular channels

2020 ◽  
Vol 24 (1 Part A) ◽  
pp. 355-365
Author(s):  
Koray Karabulut
Keyword(s):  
Heat Transfer ◽  
Pressure Drop ◽  
Heat Exchangers ◽  
Navier Stokes ◽  
Working Fluid ◽  
Inlet Temperature ◽  
Ansys Fluent ◽  
Number Range ◽  
Plate Heat ◽  
Corrugated Channel

Plate heat exchangers have a widespread usage and the simplest parallel plate channel structures. Cross-corrugated ducts are basic channel geometries used in the plate heat exchangers. In this study, the increasing of heat transfer from the cross-corrugated triangular ducts by inserting triangular baffles with different placement angles into the channel upper side and pressure drop have been numerically investigated. Numerical calculations have been carried out to solve Navier-Stokes and energy equations by employing k-? turbulence model as 3-D and steady with ANSYS-FLUENT program. While inlet temperature of the air used as working fluid is 293 K, constant surface temperature values of the the lower corrugated channel walls are 373 K. The height of the baffle and apex angle of the corrugated duct have been taken constant as 0.5 H and 60?, respectively. Investigated Reynolds number range is 1000-6000 while the baffle placement angles are 30?, 45?, 60?, and 90?. Numerical results of this study are within 3.53% deviation with experimental study existed in literature. The obtained results have been presented as mean Nusselt number temperature and pressure variations of the fluid for each baffle angle. The temperature and velocity vector contour distributions have been also assessed for different Reynolds numbers and baffle angles. The value of the Num for the corrugated channel with 60? baffle angle is 8.2% higher than that of the 90? for the Re = 4000. Besides, for Re = 1000 the value of the pressure drop is 39% lower in the channel with 60? baffle angle than that of 90?.

scholarly journals Numerical Investigation of the Effect of Sudden Expansion Ratio of Solid Fuel Ramjet Combustor with Swirling Turbulent Reacting Flow

Energies ◽  
2019 ◽  
Vol 12 (9) ◽  
pp. 1784 ◽  
Author(s):  
Weixuan Li ◽  
Xiong Chen ◽  
Wenxiang Cai ◽  
Omer Musa
Keyword(s):  
Heat Transfer ◽  
Solid Fuel ◽  
Expansion Ratio ◽  
Swirl Flow ◽  
The Self ◽  
Sudden Expansion ◽  
Reacting Flow ◽  
Reattachment Point ◽  
Regression Rate ◽  
Ramjet Combustor

In this paper, the effect of sudden expansion ratio of solid fuel ramjet (SFRJ) combustor is numerically investigated with swirl flow. A computational fluid dynamics (CFD) code is written in FORTRAN to simulate the combustion and flow patterns in the combustion chamber. The connected-pipe facility is used to perform the experiment with swirl, and high-density Polyethylene (HDPE) is used as the solid fuel. The investigation is performed with different sudden expansion ratios, in which the port and inlet diameters are independently varied. The results indicated that the self-sustained combustion of the SFRJ occurs around the reattachment point at first, and then the heat released in reattachment point is used to achieve the self-sustained combustion in the redevelopment zone. The average regression rate is proportional to the sudden expansion ratio for the cases with a fixed port diameter, which is mainly dominated by the enhancement of heat transfer in backward-facing step. However, the average regression rate is inversely proportional to the sudden expansion ratio for the cases with fixed inlet diameter, which is influenced by the heat transfer mechanism of developed turbulent flow in the redevelopment zone.

Analysis on the Effect of a Non-Uniform Inlet Profile on Heat Transfer and Fluid Flow in Turbine Stages

2010 ◽  
Author(s):  
Salvadori Simone ◽  
Francesco Montomoli ◽  
Francesco Martelli ◽  
Kam S. Chana ◽  
Imran Qureshi ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Temperature Profile ◽  
Thermal Load ◽  
Thermal Loading ◽  
Radial Profile ◽  
Experimental Studies ◽  
Test Facility ◽  
Inlet Temperature ◽  
Inlet Conditions ◽  
Hot Streak

This paper presents an investigation of the aerothermal performance of a modern unshrouded high pressure (HP) aeroengine turbine subject to non-uniform inlet temperature profile. The turbine used for the study was the MT1 turbine installed in the QinetiQ Turbine Test Facility (TTF) based in Farnborough (UK). The MT1 turbine is a full scale transonic HP turbine, and is operated in the test facility at the correct non-dimensional conditions for aerodynamics and heat transfer. Datum experiments of aero-thermal performance were conducted with uniform inlet conditions. Experiments with nonuniform inlet temperature were conducted with a temperature profile that had a non-uniformity in the radial direction defined by (Tmax−Tmin)/T = 0.355, and a non-uniformity in the circumferential direction defined by (Tmax−Tmin)/T = 0.14. This corresponds to an extreme point in the engine cycle, in an engine where the non-uniformity is dominated by the radial distribution. Accurate experimental area surveys of the turbine inlet and exit flows were conducted, and detailed heat transfer measurements were obtained on the blade surfaces and end-walls. These results are analysed with the unsteady numerical data obtained using the in-house HybFlow code developed at the University of Firenze. Two particular aspects are highlighted in the discussion: prediction confidence for state of the art computational fluid dynamics (CFD) and impact of real conditions on stator-rotor thermal loading. The efficiency value obtained with the numerical analysis is compared with the experimental data and a 0.8% difference is found and discussed. A study of the flow field influence on the blade thermal load has also been detailed. It is shown that the hot streak migration mainly affects the rotor pressure side from 20% to 70% of the span, where the Nusselt number increases by a factor of 60% with respect to the uniform case. Furthermore, in this work it has been found that a nonuniform temperature distribution is beneficial for the rotor tip, contrary to the results found in the open literature. Although the hot streak is affected by the pressure gradient across the tip gap, the radial profile (which dominates the temperature profile being considered) is not fully mixed out in passing through the HP stage, and contributes significantly to cooling the turbine casing. A design approach not taking into account these effects will underestimate to rotor life near the tip and the thermal load at mid-span. The temperature profile that has been used in both the experiments and CFD is the first simulation of an extreme cycle point (more than twice the magnitude of distortion all previous experimental studies): it represents an engine-take-off condition combined with the full combustor cooling. The research was part of the EU funded TATEF2 (Turbine Aero-Thermal External Flows 2) programme.

Finite Analytic Numerical Solution Axisymmetric Navier-Stokes and Energy Equations

1983 ◽  
Vol 105 (3) ◽  
pp. 639-645 ◽  
Author(s):  
Ching-Jen Chen ◽  
Young Hwan Yoon
Keyword(s):  
Heat Transfer ◽  
Numerical Solution ◽  
Numerical Method ◽  
Stream Function ◽  
Analytic Solution ◽  
Numerical Solutions ◽  
Stokes Equations ◽  
Navier Stokes ◽  
Inlet Temperature ◽  
Local Analytic Solution

Connective heat transfer for steady-state laminar flow in axisymmetric coordinates is considered. Numerical solutions for flow pattern and temperature distribution are obtained by the finite analytic numerical method applied to the Navier-Stokes equations expressed in terms of vorticity and stream function, and the energy equation. The finite analytic numerical method differs from other numerical methods in that it utilizes a local analytic solution in an element of the problem to construct the total numerical solution. Finite analytic solutions of vorticity, stream function, temperature, and heat transfer coefficients for flow with Reynolds numbers of 5, 100, 1000, and 2000, and Prandtl numbers of 0.1, 1.0, and 10.0 with uniform grid sizes, are reported for an axisymmetric pipe with a sudden expansion and contraction. The wall temperature is considered to be isothermal and differs from the inlet temperature. It is shown that the finite analytic is stable, converges rapidly, and simulates the convection of fluid flow accurately, since the local analytic solution is capable of simulating automatically the influence of skewed convection through the element boundary on the interior nodal values, thereby minimizing the false numerical diffusion.

Effect of Simulated Combustor Temperature Nonuniformity on HP Vane and Endwall Heat Transfer: An Experimental and Computational Investigation

2010 ◽  
Author(s):  
Imran Qureshi ◽  
Arrigo Beretta ◽  
Thomas Povey
Keyword(s):  
Heat Transfer ◽  
Guide Vane ◽  
Research Programme ◽  
Test Facility ◽  
Inlet Temperature ◽  
Computational Investigation ◽  
Nozzle Guide Vane ◽  
Inlet Conditions ◽  
Nozzle Guide ◽  
Computational Predictions

This paper presents experimental measurements and computational predictions of surface and endwall heat transfer for a high-pressure (HP) nozzle guide vane (NGV) operating as part of a full HP turbine stage in an annular rotating turbine facility, with and without inlet temperature distortion (hot-streaks). A detailed aerodynamic survey of the vane surface is also presented. The test turbine was the unshrouded MT1 turbine, installed in the Turbine Test Facility (previously called Isentropic Light Piston Facility) at QinetiQ, Farnborough UK. This is a short duration facility, which simulates engine representative M, Re, non-dimensional speed and gas-to-wall temperature ratio at the turbine inlet. The facility has recently been upgraded to incorporate an advanced second-generation combustor simulator, capable of simulating well-defined, aggressive temperature profiles in both the radial and circumferential directions. This work forms part of the pan-European research programme, TATEF II. Measurements of HP vane and endwall heat transfer obtained with inlet temperature distortion are compared with results for uniform inlet conditions. Steady and unsteady CFD predictions have also been conducted on vane and endwall surfaces, using the Rolls-Royce CFD code HYDRA to complement the analysis of experimental results. The heat transfer measurements presented in this paper are the first of their kind in the respect that the temperature distortion is representative of an extreme cycle point measured in the engine situation, and was simulated with good periodicity and with well defined boundary conditions in the test turbine.

Gas Turbines Blade Heat Transfer and Internal Swirl Cooling Flow Experimental Study Using Liquid Crystals and Three-Dimensional Stereo-Particle Imaging Velocimetry

2021 ◽  
pp. 1-31
Author(s):  
Daisy Galeana ◽  
Asfaw Beyene
Keyword(s):  
Heat Transfer ◽  
Liquid Crystals ◽  
Gas Turbine ◽  
Gas Turbines ◽  
Convective Heat Transfer Coefficient ◽  
Swirl Flow ◽  
Inlet Temperature ◽  
Cooling Flow ◽  
Blade Cooling ◽  
The Impact

Abstract The challenging engineering intricacies related to improving efficiency of a gas turbine engine comes with the need to maximize the internal cooling of the turbine blade to withstand the high turbine inlet temperature. Understanding the fluid mechanics and heat transfer of internal blade cooling is therefore of paramount importance. This paper presents the impact of swirl cooling flow on the heat transfer of a gas turbine chamber to understand the mechanics of internal blade cooling. The focus is the continuous swirl flow that must be maintained via nonstop injection of tangential flow, whereby swirl flow is generated. The impact of swirl cooling flow variation considers the velocity fields measured using stereo particle image velocimetry, the wall temperature and the convective heat transfer coefficient measured by liquid crystals and system of infrared thermography. Flow behavior and heat transfer at three Reynolds numbers ranging from 7,000 to 21,000 and the average profiles of axial and radial, magnitudes of velocity, and Nusselt numbers are given to research the direct effects of the circular chamber shape. Heat transfer results are measured and collected continuously after the system is heat-soaked to the required temperature. As part of the results relatively low heat transfer rates were observed near the upstream end of the circular chamber, resulting from a low momentum swirl flow as well as crossflow effects. The Thermochromic Liquid Crystal heat transfer results exemplify how the Nu measured favorably at the midstream of the chamber and values decline downstream.

The Effect of the Corrugation Rib Angle of Attack on the Fluid Flow and Heat Transfer Characteristics Inside Corrugated Ribbed Passage

2011 ◽  
Vol 133 (8) ◽  
Author(s):  
A. M. I. Mohamed ◽  
R. Hoettiba ◽  
A. M. Saif
Keyword(s):  
Heat Transfer ◽  
Fluid Flow ◽  
Heat Transfer Enhancement ◽  
Angle Of Attack ◽  
Navier Stokes ◽  
Transfer Enhancement ◽  
Heat Transfer Characteristics ◽  
Transfer Characteristics ◽  
Flow And Heat Transfer ◽  
Flow Field Characteristics

Heat transfer enhancement using corrugated ribbed passages is one of the common enhancement techniques inside heat exchangers. The present study investigated numerically the effect of the corrugation rib angle of attack on the fluid flow and heat transfer characteristics inside the corrugated ribbed passage. The commercial computational fluid dynamics code PHOENICS 2006 was used to perform the numerical analysis by solving the Navier–Stokes and energy equations. The experimental part of this study was used only to validate the numerical model, and a good agreement between the experimental results and the model was obtained. The flow field characteristics and heat transfer enhancement were numerically investigated for different corrugated rib angles of attack as follows: 90 deg, 105 deg, 120 deg, 135 deg, and 150 deg. The corrugation rib angle of attack has a great effect on the reversed flow zone, the flow reattachments, and the enhancement of the heat transfer coefficient through the duct. The recommended rib angle of attack, which gives the optimum thermohydraulic performance, is found to be between 135 deg and 150 deg. The value of the maximum thermohydraulic performance is about 3.6 for the 150 deg rib angle of attack at a Reynolds number equal to 10,000.

Analysis on the Effect of a Nonuniform Inlet Profile on Heat Transfer and Fluid Flow in Turbine Stages

2011 ◽  
Vol 134 (1) ◽  
Author(s):  
Salvadori Simone ◽  
Francesco Montomoli ◽  
Francesco Martelli ◽  
Kam S. Chana ◽  
Imran Qureshi ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Temperature Profile ◽  
Thermal Load ◽  
Thermal Loading ◽  
Radial Profile ◽  
Experimental Studies ◽  
Test Facility ◽  
Inlet Temperature ◽  
Inlet Conditions ◽  
Hot Streak

This paper presents an investigation of the aerothermal performance of a modern unshrouded high-pressure (HP) aero-engine turbine subject to nonuniform inlet temperature profile. The turbine used for this study was the MT1 turbine installed in the QinetiQ turbine test facility based in Farnborough (UK). The MT1 turbine is a full scale transonic HP turbine, and is operated in the test facility at the correct nondimensional conditions for aerodynamics and heat transfer. Datum experiments of aerothermal performance were conducted with uniform inlet conditions. Experiments with nonuniform inlet temperature were conducted with a temperature profile that had a nonuniformity in the radial direction defined by (Tmax−Tmin)/T¯=0.355, and a nonuniformity in the circumferential direction defined by (Tmax−Tmin)/T¯=0.14. This corresponds to an extreme point in the engine cycle, in an engine where the nonuniformity is dominated by the radial distribution. Accurate experimental area surveys of the turbine inlet and exit flows were conducted, and detailed heat transfer measurements were obtained on the blade surfaces and end-walls. These results are analyzed with the unsteady numerical data obtained using the in-house HybFlow code developed at the University of Firenze. Two particular aspects are highlighted in the discussion: prediction confidence for state of the art computational fluid dynamics (CFD) and impact of real conditions on stator-rotor thermal loading. The efficiency value obtained with the numerical analysis is compared with the experimental data and a 0.8% difference is found and discussed. A study of the flow field influence on the blade thermal load has also been detailed. It is shown that the hot streak migration mainly affects the rotor pressure side from 20% to 70% of the span, where the Nusselt number increases by a factor of 60% with respect to the uniform case. Furthermore, in this work, it has been found that a nonuniform temperature distribution is beneficial for the rotor tip, contrary to the results found in open literature. Although the hot streak is affected by the pressure gradient across the tip gap, the radial profile (which dominates the temperature profile being considered) is not fully mixed out in passing through the HP stage, and contributes significantly to cooling the turbine casing. A design approach not taking into account these effects will underestimate the rotor life near the tip and the thermal load at midspan. The temperature profile that has been used in both experiments and CFD is the first simulation of an extreme cycle point (more than twice the magnitude of distortion of all previous experimental studies): It represents an engine-take-off condition combined with the full combustor cooling. This research was part of the EU funded Turbine AeroThermal External Flows 2 program.

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