scholarly journals Combustion in a supersonic flow using a pylon equipped with a plasma actuator

2021 ◽  
Vol 2100 (1) ◽  
pp. 012017
Author(s):  
A A Firsov ◽  
N S Kolosov
Keyword(s):  
Supersonic Flow ◽  
Flow Rate ◽  
Energy Input ◽  
Supersonic Flows ◽  
Plasma Actuator ◽  
Combustion Chambers ◽  
Fuel Flow Rate ◽  
Plasma Assisted Combustion ◽  
Fuel Flow ◽  
Wide Range

Abstract Plasma-assisted combustion approach is well known for organizing stable ignition and flame holding in supersonic flows in model scramjet combustion chambers. In this work, a new geometry of pylon equipped by electrodes relative to developed earlier was proposed and experimentally investigated. Stable ignition and flame holding were obtained over a wide range of fuel flow rate and discharge currents. Reducing of the energy input in comparison with the previously considered configurations was also demonstrated.

An Experimental Investigation of HCCI Combustion Stability Using N-Heptane

2007 ◽  
Author(s):  
Hailin Li ◽  
W. Stuart Neill ◽  
Wally Chippior ◽  
Joshua D. Taylor
Keyword(s):  
Heat Release ◽  
Flow Rate ◽  
Combustion Process ◽  
Operating Conditions ◽  
Combustion Stability ◽  
Fuel Flow Rate ◽  
Fuel Flow ◽  
Air Temperatures ◽  
Wide Range ◽  
Cyclic Variations

In this paper, cyclic variations in the combustion process of a single-cylinder HCCI engine operated with n-heptane were measured over a range of intake air temperatures and pressures, compression ratios, air/fuel ratios, and exhaust gas recirculation (EGR) rates. The operating conditions produced a wide range of combustion timings from overly advanced combustion where knocking occurred to retarded combustion where incomplete combustion was detected. Cycle-to-cycle variations were shown to depend strongly on the crank angle phasing of 50% heat release and fuel flow rate. Combustion instability increased significantly with retarded combustion phasing especially when the fuel flow rate was low. Retarded combustion phasing can be tolerated when the fuel flow rate is high. It was also concluded that the cyclic variations in imep are primarily due to the variations in the total heat released from cycle-to-cycle. The completeness of the combustion process in one cycle affects the in-cylinder conditions and resultant heat release in the next engine cycle.

Formation of Soot in Ethylene–Air Partially Premixed Flames Over a Wide Range of Premixedness

2017 ◽  
Vol 139 (12) ◽  
Author(s):  
Aritra Chakraborty ◽  
Satya R. Chakravarthy
Keyword(s):  
Flow Rate ◽  
Volume Fraction ◽  
Premixed Flames ◽  
Soot Volume Fraction ◽  
Premixed Flame ◽  
Fuel Flow Rate ◽  
Fuel Flow ◽  
Wide Range ◽  
Partially Premixed Flames ◽  
Partially Premixed

This paper reports an investigation of soot formation in ethylene–air partially premixed flames (PPFs) over a wide range of premixedness. An axisymmetric co-flow configuration is chosen to establish PPFs from the fully nonpremixed to fully premixed conditions. Reducing the fuel flow rate as a percentage of the maximum from the core stream and supplying the same to the annular stream leads to stratification of the reactant concentrations. The thermal power, overall equivalence ratio, and the average velocity in both the streams are maintained constant under all conditions. The soot volume fraction is estimated by light attenuation method, and laser-induced incandescence (LII) is performed to map the soot distribution in the flow field. The soot volume fraction is observed to exhibit an “S”-type trend as the conditions are traversed from near the premixed to the nonpremixed regimes. That is, when traversing from the nonpremixed to near-premixed regime, below 60% fuel flow rate in core, the soot volume fraction drops drastically. The onset of sooting in the PPFs is clearly seen to be at the tip of the rich-premixed flame (RPF) branch of their triple flame structure, which advances upstream toward the base of the flame as the premixing is reduced. The S-type variation is clearly the effect of partial premixing, more specifically due to the presence of the lean premixed flame (LPF) branch of the triple flame. LII intensities are insufficient to capture the upstream advance of the soot onset with decreased premixedness. So, a quick and inexpensive technique to isolate soot luminescence through flame imaging is presented in the paper involving quasi-simultaneous imaging with a 650 nm and a BG-3 filter using a normal color camera.

Dynamic Simulation of a HRSG System for a Given Start-Up/Shut Down Curve

2011 ◽  
Author(s):  
Hun Cha ◽  
Yoo Seok Song ◽  
Kyu Jong Kim ◽  
Jung Rae Kim ◽  
Sung Min KIM
Keyword(s):  
Dynamic Analysis ◽  
Gas Turbine ◽  
Flow Rate ◽  
Exhaust Gas ◽  
Fuel Flow Rate ◽  
Fuel Flow ◽  
Start Up ◽  
Gas Turbine Exhaust ◽  
Main Steam ◽  
Duct Burner

An inappropriate design of HRSG (Heat Recovery Steam Generator) may lead to mechanical problems including the fatigue failure caused by rapid load change such as operating trip, start-up or shut down. The performance of HRSG with dynamic analysis should be investigated in case of start-up or shutdown. In this study, dynamic analysis for the HRSG system was carried out by commercial software. The HRSG system was modeled with HP, IP, LP evaporator, duct burner, superheater, reheater and economizer. The main variables for the analysis were the temperature and mass flow rate from gas turbine and fuel flow rate of duct burner for given start-up (cold/warm/hot) and shutdown curve. The results showed that the exhaust gas condition of gas turbine and fuel flow rate of duct burner were main factors controlling the performance of HRSG such as flow rate and temperature of main steam from final superheater and pressure of HP drum. The time delay at the change of steam temperature between gas turbine exhaust gas and HP steam was within 2 minutes at any analysis cases.

Model Analysis of Syngas Combustion and Emissions for a Micro Gas Turbine

2015 ◽  
Vol 137 (6) ◽  
Author(s):  
Chi-Rong Liu ◽  
Hsin-Yi Shih
Keyword(s):  
Gas Turbine ◽  
Flow Rate ◽  
Heat Input ◽  
Emission Characteristics ◽  
Nox Emissions ◽  
Fuel Flow Rate ◽  
Micro Gas Turbine ◽  
Fuel Flow ◽  
Temperature Distributions ◽  
Flame Structures

The purpose of this study is to investigate the combustion and emission characteristics of syngas fuels applied in a micro gas turbine, which is originally designed for a natural gas fired engine. The computation results were conducted by a numerical model, which consists of the three-dimension compressible k–ε model for turbulent flow and PPDF (presumed probability density function) model for combustion process. As the syngas is substituted for methane, the fuel flow rate and the total heat input to the combustor from the methane/syngas blended fuels are varied with syngas compositions and syngas substitution percentages. The computed results presented the syngas substitution effects on the combustion and emission characteristics at different syngas percentages (up to 90%) for three typical syngas compositions and the conditions where syngas applied at fixed fuel flow rate and at fixed heat input were examined. Results showed the flame structures varied with different syngas substitution percentages. The high temperature regions were dense and concentrated on the core of the primary zone for H2-rich syngas, and then shifted to the sides of the combustor when syngas percentages were high. The NOx emissions decreased with increasing syngas percentages, but NOx emissions are higher at higher hydrogen content at the same syngas percentage. The CO2 emissions decreased for 10% syngas substitution, but then increased as syngas percentage increased. Only using H2-rich syngas could produce less carbon dioxide. The detailed flame structures, temperature distributions, and gas emissions of the combustor were presented and compared. The exit temperature distributions and pattern factor (PF) were also discussed. Before syngas fuels are utilized as an alternative fuel for the micro gas turbine, further experimental testing is needed as the modeling results provide a guidance for the improved designs of the combustor.

scholarly journals A Method to Measure the Fuel Distribution and the Fuel Captured by V–Gutter Flameholder in High Speed Airstream

1985 ◽  
Author(s):  
Gu Shan-Jian ◽  
Yang Mao-Lin ◽  
Li Xiang-Yi
Keyword(s):  
Flow Rate ◽  
Experimental Error ◽  
High Speed ◽  
Fuel Flow Rate ◽  
Fuel Distribution ◽  
Fuel Flow ◽  
Sampling Condition ◽  
Detailed Determination

A method to measure the fuel distribution and the percentage of fuel flow rate captured by a V-gutter flameholder in a high speed airstream has been developed. The effects of configuration and size of the probe and temprature of the sample mixture in the probe on measurement have been investigated. The detailed determination of isokinetic sampling condition is described. The effects of V-gutter geometry on flowfield have been considered. The total experimental error is of the order ±5%.

System Level Analysis of Acoustically Forced Nonpremixed Swirling Flames

2014 ◽  
Vol 6 (3) ◽  
Author(s):  
Uyi Idahosa ◽  
Saptarshi Basu ◽  
Ankur Miglani
Keyword(s):  
Heat Release ◽  
Flow Rate ◽  
Ccd Camera ◽  
Time Dependent ◽  
Fuel Flow Rate ◽  
Fuel Flow ◽  
Flame Response ◽  
Rate Oscillations ◽  
Swirling Flames ◽  
Flame Sheet

This paper reports an experimental investigation of dynamic response of nonpremixed atmospheric swirling flames subjected to external, longitudinal acoustic excitation. Acoustic perturbations of varying frequencies (fp = 0–315 Hz) and velocity amplitudes (0.03 ≤ u′/Uavg ≤ 0.30) are imposed on the flames with various swirl intensities (S = 0.09 and 0.34). Flame dynamics at these swirl levels are studied for both constant and time-dependent fuel flow rate configurations. Heat release rates are quantified using a photomultiplier (PMT) and simultaneously imaged with a phase-locked CCD camera. The PMT and CCD camera are fitted with 430 nm ±10 nm band pass filters for CH* chemiluminescence intensity measurements. Flame transfer functions and continuous wavelet transforms (CWT) of heat release rate oscillations are used in order to understand the flame response at various burner swirl intensity and fuel flow rate settings. In addition, the natural modes of mixing and reaction processes are examined using the magnitude squared coherence analysis between major flame dynamics parameters. A low-pass filter characteristic is obtained with highly responsive flames below forcing frequencies of 200 Hz while the most significant flame response is observed at 105 Hz forcing mode. High strain rates induced in the flame sheet are observed to cause periodic extinction at localized regions of the flame sheet. Low swirl flames at lean fuel flow rates exhibit significant localized extinction and re-ignition of the flame sheet in the absence of acoustic forcing. However, pulsed flames exhibit increased resistance to straining due to the constrained inner recirculation zones (IRZ) resulting from acoustic perturbations that are transmitted by the co-flowing air. Wavelet spectra also show prominence of low frequency heat release rate oscillations for leaner (C2) flame configurations. For the time-dependent fuel flow rate flames, higher un-mixedness levels at lower swirl intensity is observed to induce periodic re-ignition as the flame approaches extinction. Increased swirl is observed to extend the time-to-extinction for both pulsed and unpulsed flame configurations under time-dependent fuel flow rate conditions.

scholarly journals A new generation of F1 race engines – hybrid power units

2016 ◽  
Vol 167 (4) ◽  
pp. 22-37 ◽  
Author(s):  
Zbigniew STĘPIEŃ
Keyword(s):  
Flow Rate ◽  
Regulatory Framework ◽  
Fuel Flow Rate ◽  
Maximum Performance ◽  
Engine Efficiency ◽  
Hybrid Power ◽  
Fuel Flow ◽  
New Generation ◽  
Technical Regulations

The paper aims at reviewing the evolution of the F1 engine technology and the associated regulatory framework governing the sport over the last 10 years. Technical regulations, in force since 2014, replaced the 2.4-liter V8 naturally aspirated engines with sophisticated hybrid units such as the 1.6-liter V6 turbocharged engines supported with energymanagement and recovery systems. Since 2014 the fundamental trend in the development of powertrains has been the advancement of their efficiency. Due to the fact that the fuel flow rate has been restricted, the maximum performance is now entirely dependent on the engine efficiency.

Effects of Burner Diameter and Fuel Type on Smoke Point and Radiation Characteristics of Diffusion Flames

2002 ◽  
Author(s):  
S. F. Goh ◽  
S. Kusadomi ◽  
S. R. Gollahalli
Keyword(s):  
Mass Flow Rate ◽  
Mass Flow ◽  
Flow Rate ◽  
Critical Mass ◽  
Smoke Point ◽  
Fuel Type ◽  
Fuel Flow Rate ◽  
Flame Radiation ◽  
Fuel Mass ◽  
Fuel Flow

The main purpose of this study was to comprehend the effects of burner diameter and fuel type on smoke point characteristics of a hydrocarbon diffusion flame and its radiation emission. The critical mass flow rate of pure fuel at this smoke point was measured. At nine different fractions of the critical mass flow rate, nitrogen gas was supplied along with the fuel to achieve smoke point. At each condition, flame radiation and flame height were measured. The axial radiation profile at the critical fuel mass flow rate for one burner was also measured. Three fuels of differing sooting propensities were used: ethylene (C2H4), propylene (C3H6), and propane (C3H8). Three different burners with inner diameters of 1.2 mm, 3.2 mm and 6.4 mm were used. Results showed that propylene had the highest critical fuel flow rate and the highest nitrogen dilution required to suppress smoking and total flame radiation, followed by ethylene and propane. For all fuels, the curves of nitrogen flow rate required for smoke suppression versus fuel flow rate exhibited a skewed bell shape. The variation of Reynolds number at the critical fuel mass flow rate with the burner diameter showed a linear relation. On the other hand, the variation of total flame radiation with burner diameter was nonlinear.

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