scholarly journals The Influence of Mixedness on Ignition for Hydrogen Direct Injection in a Constant Volume Combustion Chamber

2018 ◽  
Author(s):  
Martia Shahsavan ◽  
Mohammadrasool Morovatiyan ◽  
John Hunter Mack
Keyword(s):  
Combustion Chamber ◽  
Ignition Delay ◽  
Gas Turbines ◽  
Flame Temperature ◽  
Constant Volume ◽  
Working Fluid ◽  
Scalar Dissipation ◽  
Mixing Rate ◽  
Constant Volume Combustion ◽  
Constant Volume Combustion Chamber

The ignition behavior of the fuel in non-premixed turbulent combustion applications such as diesel engines and gas turbines is dependent on the mixing rate of the injected fuel and the working fluid. In this study, three-dimensional modeling of hydrogen injection into a constant volume combustion chamber (CVCC) is used to investigate the correlation between the mixing rate and important parameters of non-premixed combustion, such as ignition delay. Mixedness is quantified using mean spatial variation, which reflects the homogeneity of the mixture, and mean scalar dissipation, which represents the local gradients of the scalar. The case studies include nitrogen and argon as working fluids; injection velocities and nozzle diameters are varied for comparison. For consistency, the injected mass is kept constant and the injection duration is adjusted accordingly. The results indicate that a strong correlation exists between ignition delay and the defined mixedness parameters. The cases with higher mixedness values lead to a shorter ignition delay and a higher maximum flame temperature. Changing the working fluid and injection parameters can effectively modify the mixedness, and consequently affect the ignition onset and flame properties.

Experimental Investigation of Spray and Combustion Characteristics of Soybean Biodiesel in a Constant-Volume Combustion Chamber: The Effects of Fuel and Ambient Gas Temperature

2013 ◽  
Author(s):  
Yifeng Wu ◽  
Ronghua Huang ◽  
Chia-fon F. Lee
Keyword(s):  
Combustion Chamber ◽  
Ignition Delay ◽  
Combustion Characteristics ◽  
Constant Volume ◽  
Gas Temperature ◽  
Soot Mass ◽  
Soybean Biodiesel ◽  
Constant Volume Combustion ◽  
Constant Volume Combustion Chamber ◽  
Ambient Gas

Effects of fuel and ambient gas temperature on the spray and combustion characteristics of soybean biodiesel were studied in a constant-volume combustion chamber. Four different fuels or fuel blends including B0, B20, B50 and B100 were investigated experimentally. The soot mass data were obtained via a new technique called forward illumination light extinction (FILE). The ambient gas temperature was varied from 700 K to 1200 K. To simulate the engine operating conditions, the ambient oxygen concentration and its density were kept at 21 % and 15 kg/m3, respectively. A higher peak pressure is found as the biodiesel content decreases. B20, B50 and B100 have a shorter ignition delay than B0 and the ignition delay decreases with increasing biodiesel content. The liquid penetration decreases with decreasing biodiesel content. Moreover, the integrated natural flame luminosity (INFL) increases with decreasing biodiesel content. Shorter flame (i.e., soot luminosity) duration and a longer delay between start of combustion (SOC) and the appearance of flame are found as the biodiesel content increases. The flame duration also increases with increasing ambient gas temperature for all fuels. Soot is lower and appears later at a lower ambient gas temperature, while it is burned out at around the same time. Near-zero soot mass was observed for all tested fuels at 700 K. A shorter soot formation process is observed for biodiesel fuels. The soot reduction using B20 and B50 is not obvious compared to B0 at a low temperature. But under the ordinary diesel engine operating condition at 1000 K, the soot reduction is significant. It is also found that the soot can be reduced by 60% and above when B100 is used in this study.

scholarly journals The Effect of Working Fluids on Premixed Hydrogen Combustion in a Constant Volume Combustion Chamber

2019 ◽  
Author(s):  
Mohammadrasool Morovatiyan ◽  
Martia Shahsavan ◽  
Jonathan Aguilar ◽  
John Hunter Mack
Keyword(s):  
Combustion Chamber ◽  
Internal Combustion Engines ◽  
Burning Velocity ◽  
Constant Volume ◽  
Partial Substitution ◽  
Partial Replacement ◽  
Working Fluid ◽  
Laminar Burning Velocity ◽  
Constant Volume Combustion ◽  
Constant Volume Combustion Chamber

Premixed combustion of hydrogen was investigated with the purpose of examining the effect of the full or partial substitution of argon for nitrogen in air on laminar burning velocity. Theoretically, this partial replacement decreases the NOx emissions and increases the thermal efficiency of internal combustion engines due to the high specific heat ratio of noble gases. An optically-accessible constant volume combustion chamber (CVCC) with central ignition was used to study flame propagation, flame morphological structure, and instability. The spherical flame development was studied using a high-speed Z-type Schlieren visualization system. Moreover, a numerical model was developed to convert the pressure rise data to laminar burning velocity. Coupling the model to a chemical equilibrium code aids in determining the burned gas properties. The experimental and numerical investigations indicate that increasing the concentration of argon as the working fluid in the mixture can increase the laminar burning velocity and extend the lean flammability limit.

scholarly journals Evaluation of the possibilities of adapting a constant volume combustion chamber for research on ignition of hypergolic propellants under low and high-pressure conditions

2018 ◽  
Vol 173 (2) ◽  
pp. 9-13
Author(s):  
Maciej KRZESICKI ◽  
Łukasz BORUC ◽  
Łukasz KAPUSTA
Keyword(s):  
High Pressure ◽  
Combustion Chamber ◽  
Ignition Delay ◽  
State Of The Art ◽  
Constant Volume ◽  
Drop Test ◽  
Test Rig ◽  
Constant Volume Combustion ◽  
Constant Volume Combustion Chamber ◽  
Hypergolic Propellants

In this study, the adaptation possibilities of a constant volume combustion chamber (CVCC) for research on the ignition of hypergolic propellants are presented. The application of hypergolic bipropellants and crucial parameters regarding their ignition behaviour are discussed. The initial studies on ignition delay measurements presented here does not cover the whole range of conditions present in practical systems where hypergolic ignition occurs. In the study, a need for an evaluation of the influence of pressure on the ignition delay was indicated as the reason to conduct research on hypergolic ignition in low and high-pressure environments. Moreover, the study reviews the state-of-the-art experimental methods of investigating the ignition under atmospheric, low and high-pressure conditions, including those utilizing a constant volume combustion chamber. The drop test was pointed out as the most commonly used method; this makes it advantageous in terms of comparing the results with those obtained by other researchers. Therefore, the drop test was selected as a method to be used in a CVCC. The test rig developed here was designed based on a CVCC initially designed for diesel sprays’ visualization in high-pressure conditions. All the required modifications, especially the design of the oxidizer dosing unit, are presented in the study.

Demonstrating a Direct-Injection Constant-Volume Combustion Chamber As a Validation Tool for Chemical Kinetic Modeling of Liquid Fuels

2018 ◽  
Author(s):  
Aaron E. Suttle ◽  
Brian T. Fisher ◽  
Dennis R. Parnell ◽  
Joshua A. Bittle
Keyword(s):  
High Pressure ◽  
Combustion Chamber ◽  
Ignition Delay ◽  
Constant Volume ◽  
Liquid Fuels ◽  
Fuel Vapor ◽  
Bulk Temperature ◽  
Validation Data ◽  
Constant Volume Combustion ◽  
Constant Volume Combustion Chamber

Supporting chemical kinetics model development with robust experimental results is the job of shock-tube, rapid compression machine, and other apparatus operators. A key limitation of many of these systems is difficulty with preparation of a fuel vapor-air mixture for heavy liquid fuels. Previous work has suggested that the Cetane Ignition Delay (CID) 510 system is capable of providing data useful for kinetics validation. Specifically, this constant-volume combustion chamber (1) can be characterized by a single bulk temperature, and (2) uses a high-pressure diesel injector to generate rapid fuel-air mixing and thus create a homogeneous mixture well before ignition. In this study, initial experiments found relatively good agreement between experiments and kinetic models for n-heptane and poor agreement for iso-octane under nominally the same ignition delay ranges for ambient conditions under which the mixture is determined to be effectively homogeneous. After excluding potential non-kinetic fuel properties as causes, further experiments highlight the high pressure sensitivity of the negative temperature coefficient (NTC) behavior. While this challenge is well known to kinetic mechanism developers, the data set included in this work (n-heptane at 5 bar and iso-octane at 5–20 bar, each for various equivalence ratios) can be added to those used for validation. The results and system characterization presented demonstrate that this combustion system is capable of capturing kinetic effects decoupled from the spray process for these primary reference fuels. Future work can leverage this capability to provide kinetics validation data for most heavy, exotic, or otherwise difficult to test liquid fuels.

scholarly journals A study on the influence of ignition energy on ignition delay time and laminar burning velocity of lean methane/air mixture in a constant volume combustion chamber

2021 ◽  
pp. 1-4
Author(s):  
Nguyen Minh Tien Nguyen
Keyword(s):  
Combustion Chamber ◽  
Ignition Delay ◽  
Delay Time ◽  
Ignition Delay Time ◽  
Burning Velocity ◽  
Constant Volume ◽  
Laminar Burning Velocity ◽  
Ignition Energy ◽  
Constant Volume Combustion ◽  
Constant Volume Combustion Chamber

This study presents the effect of ignition energy (Eig) on ignition delay time (tdelay) and uncertainty of laminar burning velocity (Su0) measurement of lean methane/air mixture in a constant volume combustion chamber. The mixture at an equivalence ratio of 0.6 is ignited using a pair of electrodes at the 2-mm spark gap. Eig is measured by integrating the product of voltage V(t) and current I(t) signals during a discharge period. The in-chamber pressure profiles are analyzed using the pressure-rise method to obtain tdelay and Su0. Su0 approximates 8.0 cm/s. Furthermore, the increasing Eig could shorten tdelay, leading to a faster combustion process. However, when Eig is greater than a critical value, called minimum reliable ignition energy (MRIE), the additional elevating Eig has the marginal effect on tdelay and Su0. The existence of MRIE supports to optimize the ignition systems and partly explains why extreme-high Eig>> MRIE has less contribution to engine performance.

scholarly journals Effect of Cylinder Air Pressure and Hot Surface Temperature on Ignition Delay of Diesel Spray in a Constant Volume Combustion Chamber

Energies ◽  
2019 ◽  
Vol 12 (13) ◽  
pp. 2565
Author(s):  
Mohammad Salman ◽  
Sung Chul Kim
Keyword(s):  
Combustion Chamber ◽  
Diesel Engines ◽  
Ignition Delay ◽  
Strong Dependence ◽  
Injection Pressure ◽  
Constant Volume ◽  
Fuel Additive ◽  
Constant Volume Combustion ◽  
Constant Volume Combustion Chamber ◽  
Hot Surface

Present-day direct injection (DI) diesel engines with a high power density of displacement are not just promoting an expansion in the utilization of high-temperature resistant alloys in pistons yet, in addition, the expanded cylinder air pressures. When the temperature of the diesel engines piston exceeds a certain limit, it assumes a critical role at the start of sprays. The target of the present investigation was to look at the effects of cylinder air pressures (CAP) (10–25 bar) and high hot surface temperatures (HST) (350–450 °C). The ignition delay (ID) of pure diesel and that of diesel with Iftex clean system D (a cetane enhancer) are investigated experimentally. The experiments are performed by using a constant volume combustion chamber (CVCC) with a single hole pintle-type nozzle mounted on its head. A strong dependence of ID on the CAPs and HSTs was observed. A CAP of 25 bar is much inferior to the precombustion pressure of DI diesel engines; however, it is the case that combustion typical features are the same in spite of an inferior CAP, HST, and injection pressure. The ID tends to decrease to very small values with an increase in either of the two parameters. At a CAP of 25 bar, the measured ID of diesel with fuel additive is 45.8% lower than the pure diesel. Further, the ID of diesel with fuel additive at a 300 bar injection pressure and 25 bar CAP decreases at a rate of close to 0.2 ms/bar.

scholarly journals Evaluation of the impact of initial temperature of the constant volume combustion chamber on a determination of ignition delay of N-heptane

2021 ◽  
Vol 1826 (1) ◽  
pp. 012077
Author(s):  
Monizi C. Lima ◽  
Jackson S. Oliveira ◽  
Carlos S. Nunes ◽  
Paulo L. F. Simões ◽  
Paulo Roberto. G. Couto ◽  
...  
Keyword(s):  
Combustion Chamber ◽  
Ignition Delay ◽  
Initial Temperature ◽  
Constant Volume ◽  
Constant Volume Combustion ◽  
Constant Volume Combustion Chamber ◽  
The Impact
Sign in / Sign up

Export Citation Format

Share Document