Quasi-1D Compressible Flow of Hydrocarbon Fuel

Cheng, Di; Fan, Xuejun; Yang, Meng

doi:10.2514/6.2012-4090

Cited by 2 publications

(3 citation statements)

References 21 publications

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“…[17]. A similar matrix assessing the effects of heat addition and friction are presented by Cheng et al [19], although the choice of compressibility functions is significantly different. An important thermodynamic property is the fundamental derivative, C, which can be related to the curvature of the isentrope in p-v coordinates through the expression…”

Section: Real Gas Aerothermodynamicsmentioning

confidence: 97%

“…(14) and the number of condensing nuclei. The other time scale is the residence time of the flow, which is defined as t r ¼ l C ave (19) where l is the length of the condensing volume along the blade's camber line and c ave is the average flow velocity. For the candidate compressor stage at supercritical operating conditions, the time scale ratio is found to be t r /t n ¼ 0.01, meaning that the time required for stable liquid droplets to form is significantly larger than the residence time of the flow inside the nucleating region.…”

Section: Condensation Effectsmentioning

confidence: 99%

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An Investigation of Real Gas Effects in Supercritical CO2 Centrifugal Compressors

Baltadjiev

Lettieri

Spakovszky

2015

Journal of Turbomachinery

124

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This paper presents a comprehensive assessment of real gas effects on the performance and matching of centrifugal compressors operating in supercritical CO2. The analytical framework combines first principles based modeling with targeted numerical simulations to characterize the internal flow behavior of supercritical fluids with implications for radial turbomachinery design and analysis. Trends in gas dynamic behavior, not observed for ideal fluids, are investigated using influence coefficients for compressible channel flow derived for real gas. The variation in the properties of CO2 and the expansion through the vapor-pressure curve due to local flow acceleration are identified as possible mechanisms for performance and operability issues observed near the critical point. The performance of a centrifugal compressor stage is assessed at different thermodynamic conditions relative to the critical point using computational fluid dynamics (CFD) calculations. The results indicate a reduction of 9% in the choke margin of the stage compared to its performance at ideal gas conditions due to variations in real gas properties. Compressor stage matching is also impacted by real gas effects as the excursion in corrected mass flow per unit area from inlet to outlet increases by 5%. Investigation of the flow field near the impeller leading edge at high flow coefficients shows that local flow acceleration causes the thermodynamic conditions to reach the vapor-pressure curve. The significance of two-phase flow effects is determined through a nondimensional parameter that relates the time required for liquid droplet formation to the residence time of the flow under saturation conditions. Applying this criterion to the candidate compressor stage shows that condensation is not a concern at the investigated operating conditions. In the immediate vicinity of the critical point however, this effect is expected to become more prominent. While the focus of this analysis is on supercritical CO2 compressors for carbon capture and sequestration (CCS), the methodology is directly applicable to other nonconventional fluids and applications.

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Section: Real Gas Aerothermodynamicsmentioning

confidence: 97%

Section: Condensation Effectsmentioning

confidence: 99%

An Investigation of Real Gas Effects in Supercritical CO2 Centrifugal Compressors

Baltadjiev

Lettieri

Spakovszky

2015

Journal of Turbomachinery

124

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“…Thereby, the intersection point act as an important bridging role in the oscillation flame-anchoring mode. The downstream fuel stream penetrates deeper thus does not intersect with the reacting layer starting from the cavity leading edge, because the momentum flux of the cross flow has been decreased by the upstream heat addition and wall friction [129,130] while isotropic onedimension analysis indicates that a Mach number of √2 , far beyond the current subsonic value, could achieve the maximum momentum flux [131]. Thickened or separated boundary layer can also be visualized in the end part of isolator and the combustor with large negative pressure gradient, while the boundary layer in the expander is thinner.…”

Section: B Temperature Fieldsmentioning

confidence: 99%

Full-scale Detached Eddy Simulation of kerosene fueled scramjet combustor based on skeletal mechanism

Yao¹,

Wang²,

Lu³

et al. 2015

20th AIAA International Space Planes and Hypersonic Systems and Technologies Conference

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Large Eddy Simulation (LES) of kerosene fueled scramjet combustor is generally scare in the literature, due mainly to the formidable computational cost arisen by complex kerosene mechanism. In this study, the skeletal reduction of a detailed reaction mechanism (2185 species/8217 steps) of aviation kerosene is conducted using directed relation graph with error propagation and sensitivity analysis (DRGEPSA) method, resulting a skeletal mechanism consisting of 39 species/153 elemental reactions for China Daqing RP-3 aviation kerosene. The comparisons of adiabatic flame temperature, total heat release, ignition delay and laminar flame speed predicted by the skeletal mechanism show an overall good accordance with the original detailed reaction mechanism. Then a three-dimensional Detached Eddy Simulation (DES) modeling based on the skeletal kerosene mechanism is employed for the numerical analysis of a full-scale scramjet combustor, which has been experimentally tested in a long-time direct connect supersonic combustion test platform (abbreviated as DTZ) assembled in Chinese Academy of Sciences (CAS). Pressure and heat flux measurement systems are attached to the combustor assembly to monitor the real-time combustion performance and provide validation data for the numerical modeling. Three cases with fuel equivalence ratios from 0.8, 1.0 to 1.2 and the same crossflow conditions at Mach 2.0 are modeled. The time-averaged static pressure and heat flux are in generally good agreement with the experiment with the peak heat flux slightly underpredicted. The instantaneous and/or time-averaged pressure, momentum, temperature and turbulence fields, which are difficult to be measured, are analyzed to reveal the main flow and combustion physics, especially those related to the flame distribution and holding. The combustion is identified as in ramjet mode for the investigated cases. With the increasing of fuel equivalence ratio, the shock train propagates upstream in the isolator and the interaction between the upstream and downstream combustion assumes different patterns.

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Quasi-1D Compressible Flow of Hydrocarbon Fuel

Cited by 2 publications

References 21 publications

An Investigation of Real Gas Effects in Supercritical CO2 Centrifugal Compressors

An Investigation of Real Gas Effects in Supercritical CO2 Centrifugal Compressors

Full-scale Detached Eddy Simulation of kerosene fueled scramjet combustor based on skeletal mechanism

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