Henning Bockhorn

Henning Bockhorn
Karlsruhe Institute of Technology | KIT · Engler Bunte Institute

Professor Dr.-Ing. Dr.-Ing. habil.

About

510
Publications
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8,520
Citations

Publications

Publications (510)
Conference Paper
While a fast and non-intrusive diagnostics of morphological particle properties, i.e., P(dP), may be realized using time-resolved laser-induced incandescence (TiRe-LII), which involves particle heating by a nanosecond laser pulse and collecting the resulting blackbody radiation, the analysis of the sub-nm layers forming CNPs demands time-consuming...
Article
A premixed and thermo-diffusively unstable turbulent hydrogen-air flame-in-a-box case is simulated in conjunction with the flame particle tracking (FPT) method. The flame is located in the flamelet regime. The focus lies on the assessment of memory effects in local flame dynamics. By tracking flame particles on an iso-surface of the flame during fl...
Article
Fully resolved numerical simulations have been conducted for laminar premixed hydrogen-air flames, in order to study the influence of unsteadiness of the flow on the local and global flame dynamics. The flames are excited with oscillating inflows at pre-defined frequencies f to assess the effect of unsteady stretch on flame dynamics, while the Damk...
Article
The impact of chemical reactions at low-temperature (i.e., low-temperature chemistry, LTC) and LTC-induced cool flames on autoignition and premixed flame propagation has been investigated extensively. However, much less analysis is made to explore the role of LTC in forced ignition of non-premixed fuel/oxidizer systems. The objective of this work i...
Article
Full-text available
The aim of this study is to investigate the impact of global operating parameters, e.g., engine speed, brake mean effective pressure, and air–fuel ratio, of a turbocharged 4-cylinder GDI engine on the reactivity of soot particles against oxidation. The knowledge of soot reactivity is crucial for optimizing gasoline particulate filter regeneration s...
Conference Paper
This work presents the further development and the validation of the Discrete Ordinates Model for thermal radiation which is implemented in OpenFOAM ® for application to packed beds of biomass particles. This radiation model is an important part of a more comprehensive model which simulates the thermal conversion of discrete phase (here for instanc...
Article
Numerical simulations have been conducted for a novel double-concentric swirl burner, which is specifically designed for combustion of sulfur with a high power density. The burner serves as a major component of an enclosed conversion cycle, which uses elemental sulfur as a carbon-free chemical energy carrier for storing solar energy. The focus of t...
Article
Full-text available
Motivated by the recent success in finding coherent structures in turbulent flows and describing their noise emission using the Resolvent Analysis (RA), the method is applied to a turbulent jet flame at Re = 15 , 0 0 0 and a corresponding non-reacting flow to investigate their axisymmetric dynamics. The RA, which in this study assumes a passive fla...
Article
Presumed probability density function (PDF) and transported PDF methods are commonly applied to model the turbulence chemistry interaction in turbulent reacting flows. However, little focus has been given to the turbulence chemistry interaction PDF closure for flame-wall interaction. In this study, a quasi-DNS of a turbulent premixed, stoichiometri...
Article
In this work a dual-pulse laser-induced incandescence method is presented, which is potentially suitable for the in-situ determination of E(m,λUV)/E(m,λNIR) in transient flows. The dual-pulse LII is irradiating a particle ensemble by two subsequent laser pulses of different wavelengths with a time delay long enough to ensure cooling of the particle...
Article
This paper is a continuation of the work we carried out in Part I (Wen et al., 2021), studying the flame structure analysis and composition space modeling of an outwardly expanding thermodiffusively unstable premixed hydrogen flame at atmospheric pressure. In this work, we focus on the case of elevated pressure (5 atm), which is particularly challe...
Article
This work focuses on flame structure analysis and composition space modeling of a multidimensional premixed hydrogen flame transitioning from a laminar stable condition to a thermodiffusively unstable state. Specifically, budget and a priori analyses are conducted based on a detailed chemistry simulation of a 2D expanding, thermodiffusively unstabl...
Conference Paper
Full-text available
Highly-resolved numerical simulations have been performed for a coaxial, twin-fluid nozzle, which is designed for fundamental research of the atomization process in entrained flow gasification (EFG). Objective of the work is to reveal specifically the influence of the relative injection angle α between the central liquid jet and the annular airflow...
Article
Full-text available
The article Quasi-DNS Dataset of a Piloted Flame with Inhomogeneous Inlet Conditions written by Thorsten Zirwes, Feichi Zhang, Peter Habisreuther, Maximilian Hansinger, Henning Bockhorn, Michael Pfitzner, Dimosthenis Trimis, was originally published Online First without Open Access.
Article
Full-text available
The objective of this study is to derive morphological and nanostructural properties of soot as well as the reactivity against low-temperature oxidation by O2 from easily measurable optical properties. First, ex-situ experiments utilizing thermogravimetric analysis (TGA) and high-resolution transmission electron microscopy (HRTEM) serve to evaluate...
Article
This study presents numerical simulations of rotary kiln reactors for wet biomass carbonization. For this, a numerical tool has been developed resolving the carbonization process in time and space. Biomass particles are represented by Lagrangian particles that collide and form a moving bed. The gas phase is treated as an Eulerian phase. Both phases...
Article
To comply with future emission regulations for internal combustion engines, system-related cold-start conditions in short-distance traffic constitute a particular challenge. Under these conditions, pollutant emissions are seriously increased due to internal engine effects and unfavorable operating conditions of the exhaust aftertreatment systems. A...
Article
Full-text available
Large eddy simulations (LES) have been carried out to calculate turbulent flame propagation in a fan-stirred combustion bomb and a Bunsen-type burner. Objective of the work is to reveal the main mechanism of increased flame wrinkling due to elevated pressure and to assess the ability of the turbulent flame-speed closure (TFC-class) combustion model...
Article
Full-text available
Due to worldwide increasingly sharpened emission regulations, the development of Gasoline Direct Injection and Diesel Direct Injection engines not only aims at the reduction of the emission of nitrogen oxides but also at the reduction of particulate emissions. Regarding present regulations, both tasks can be achieved solely with the help of exhaust...
Article
Full-text available
The numerical investigation of quenching distances in laminar flows is mainly concerned with two setups: head-on quenching (HOQ) and side-wall quenching (SWQ). While most of the numerical work has been conducted for HOQ with good agreement between simulation and experiment, far less analysis has been done for SWQ. Most of the SWQ simulations used s...
Article
Full-text available
Identifying combustion regimes in terms of premixed and non-premixed characteristics is an important task for understanding combustion phenomena and the structure of flames. A quasi-DNS database of the compositionally inhomogeneous partially premixed Sydney/Sandia flame in configuration FJ-5GP-Lr75-57 is used to directly compare different types of...
Article
To comply with future emission regulations for internal combustion engines, system-related cold-start conditions in short-distance traffic constitute a particular challenge. Under these conditions, pollutant emissions are seriously increased due to internal engine effects and unfavorable operating conditions of the exhaust aftertreatment systems. A...
Article
Full-text available
A burner system for the efficient and clean combustion of sulfur is introduced, which serves as a key component in a novel solar power cycle using sulfur as chemical storage medium of solar energy. In order to validate the proposed design concept, highly-resolved numerical simulations have been performed. The current setup is operated with a therma...
Article
In this paper the evolution of morphological and nanostructural properties of soot primary particles during low-temperature oxidation with oxygen is presented. Soot primary particles and aggregates from three soot samples with varying morphological and nanostructural initial properties were investigated by highresolution transmission electron micro...
Article
The numerical investigation of quenching distances in laminar flows is mainly concerned with two setups: head-on quenching (HOQ) and side-wall quenching (SWQ). While most of the numerical work has been conducted for HOQ with good agreement between simulation and experiment, far less analysis has been done for SWQ. Most of the SWQ simulations used s...
Article
Full-text available
Large Eddy Simulations of the Sydney mixed-mode flame with inhomogeneous inlet (FJ200-5GP-Lr75-57) are performed using the Eulerian Stochastic Fields (ESF) transported probability functions method to account for the sub-grid scale turbulence–chemistry interaction, to demonstrate the suitability of the ESF method for mixed-mode combustion. An analyt...
Article
Flame particles (FP) are massless, virtual particles which follow material points on the flame surface. This work presents a tracking algorithm for FPs which utilizes barycentric coordinates. The methodology can be used with any cell shape in the computational mesh and allows computationally fast spatial interpolation as well as efficient determina...
Article
Full-text available
Understanding and characterizing ignition of flammable mixtures by hot particles is important for assessing and reducing the risk of accidental ignition and explosion in industry and aviation. Recently, many studies have been conducted for ignition of gaseous mixtures by hot particles. However, the effects of low-temperature chemistry (LTC) on igni...
Article
Highly-resolved numerical simulations employing detailed reaction kinetics and molecular transport have been applied to flame-wall interaction (FWI) of laminar premixed flames. A multiple plane-jet flame (2D) has been considered, which is operated with premixed methane/air mixtures at atmospheric conditions and with different equivalence ratios. Fr...
Conference Paper
Carbonization is a key process to increase the energy density of high moisture-containing biomasses and biogenic wastes and to provide multipurpose raw chemicals for further applications. Steam-assisted carbonization is a kind of slow pyrolysis, in which wet biomass is treated continuously in superheated steam at elevated temperature and atmospheri...
Article
Full-text available
Recently we demonstrated the simultaneous detection of the chemiluminescence of the radicals OH* (310 nm) and CH* (430 nm), as well as the thermal radiation of soot in laminar and turbulent methane/air diffusion flames. As expected, a strong spatial and temporal coupling of OH* and CH* in laminar and moderate turbulent flames was observed. Taking a...
Article
Full-text available
In recent years, the tomographic visualization of laminar and turbulent flames has received much attention due to the possibility of observing combustion processes on-line and with high temporal resolution. In most cases, either the spectrally non-resolved flame luminescence or the chemiluminescence of a single species is detected and used for the...
Article
The gradual global tightening of emission legislation for particulate matter emissions requires the development of new gasoline engine exhaust aftertreatment systems. For this reason, the development of gasoline direct injection engines aims at the reduction of particulate emissions by application of a Gasoline Particulate Filter (GPF). The regener...
Article
Full-text available
A quasi-DNS of the partially premixed turbulent Sydney flame in configuration FJ200-5GP-Lr75-57 has been conducted using detailed molecular diffusion for multi-component mixtures and complex reaction mechanisms. In order to study flame dynamics like regime transition in this flame for the development of new combustion models and to directly compare...
Article
Spark discharge generators enable a fast, reliable, continuous, and highly reproducible production of nanoparticle aerosols along with a widely tunable size distribution. Graphite spark discharge generators have been particularly applied for studies of instrument calibration, filter testing, soot reactivity studies, and in toxicological risk evalua...
Article
Full-text available
In many applications like gas turbines, the combustion process can take place in partially‐premixed environments, where fuel and oxidizer are not fully mixed before combustion. These partially‐premixed or mixed‐mode flames have become a focus of combustion research in the last few years. In this work, a quasi‐DNS of an experimentally measured burne...
Conference Paper
Side-wall quenching (SWQ) is investigated numerically with steady-state 2D and 3D simulations of an experimental flame setup [1, 2]. The simulations fully resolve the flame and employ detailed reaction mechanisms as well as molecular diffusion models. Quenching distances are determined based on different markers: chemiluminescent species, temperatu...
Conference Paper
In recent years, the tomographic visualization of laminar and turbulent flames has received much attention. In most cases, either the integral flame luminescence or the chemiluminescence of a single species is detected and used for the tomographic reconstruction. In this work, we present a novel 2D emission tomographic setup that allows for the sim...
Conference Paper
Rotary reactors are known for their flexibility with regard to process conditions and for reliable, easily adjustable product quality. This paper presents and validates the implementation of an Euler-Lagrange method for the numerical simulation of dense particle flows with OpenFOAM, which can efficiently simulate moving-bed flow behavior in large-s...
Article
Jatropha curcas cultivation is being undertaken mainly for fuel oil production, but it also results in biomass residues such as fruit husks, seed shell, seed cake or kernel meal, together making up >80% of the dry fruit weight. Additionally, plant biomass from crop management is also generated. The various biomass residue fractions have gross energ...
Article
This work presents a numerical study of the initial turbulent flow characteristics prior to ignition in a fan-stirred combustion vessel. The moving mesh methodology has been applied to account for the rotational movement of eight fans mounted within the vessel. The transient, highly-resolved numerical simulations resolve the 3D turbulent flow field...
Article
Full-text available
The thermoacoustic sound generation mechanisms of lean premixed laminar and turbulent flames are investigated by a two-step approach. First, the conservation equations of a reacting compressible fluid are solved. This solution is used to determine the acoustic source terms of the acoustic perturbation equations (APE). Second, the contributions of t...
Chapter
The computation of chemical reaction rates is commonly the performance bottleneck in CFD simulations of turbulent combustion with detailed chemistry. Therefore, an optimization method is used where C++ source code is automatically generated for arbitrary reaction mechanisms. The generated code is highly optimized for the chosen mechanism and contai...
Article
Thermochemistry and kinetic pathways on the 2‐butanone‐4‐yl (CH3C(=O)CH2CH2•) + O2 reaction system are determined. Standard enthalpies, entropies, and heat capacities are evaluated using the G3MP2B3, G3, G3MP3, CBS‐QB3 ab initio methods, and the B3LYP/6‐311g(d,p) density functional calculation method. The CH3C(=O)CH2CH2• radical + O2 association re...
Conference Paper
Side-wall quenching (SWQ) is investigated with 2D and 3D simulations of an experimentally measured flame setup. Quenching distances are identified by different markers, based on OH, OH* and CH* concentration profiles as well as temperature, which show qualitatively good agreement with measurements for two flames at different equivalence ratios. 3D...
Conference Paper
Full-text available
This paper presents a HRTEM image analysis method for quantitative and reproducible analysis of the carbon nanostructure in soot and Carbon Black nanoparticles. The method applies top-hat transformation and Gaussian low-pass filtering and eliminates the negative impacts of both methods by image comparison. The subsequent binarization uses a thresho...
Article
This work assesses the effect of using different closure concepts for the spatially filtered mean reaction rate on the resolved spectral response of turbulent heat release in large eddy simulations (LESs). Two well-known combustion models, the turbulent flame speed closure (TFC) and the dynamically thickened flame (DTF) models have been applied to...
Article
The paper presents a study on the combustion (oxidation) of S2 over a wide range of air/fuel ratios using a sulfur oxygen mechanism and numerical flame calculations; reaction zone structures, as well as the corresponding laminar burning velocities are reported. The numerical simulations employed a detailed reaction mechanism derived from an H/O/S-c...
Article
Full-text available
The pyrolysis of chlorobenzene under dilute atmosphere and quasi-atmospheric pressure was studied at temperatures from 800 to 1150 K using a fused silica jet stirred reactor (JSR) and from 800 to 1250 K in an alumina tubular reactor. Chlorobenzene was chosen as a surrogate to model the thermal decomposition of polychlorinated biphenyls (PCBs). In t...
Article
Several chemical reactions related to the oxidation and combustion of sulfur are investigated using a number of computational chemistry methods with the objective of determining appropriate methods for use in developing an elementary reaction mechanism for oxidation of sulfur. Calculations are focused on thermochemical properties and reaction energ...
Article
Full-text available
Exposure to exogenous noxae, such as particulate matter, can trigger acute aggravations of allergic asthma-a chronic inflammatory airway disease. We tested whether Carbon Black nanoparticles (CBNP) with or without surface polycyclic aromatic hydrocarbons (PAH) aggravate an established allergic airway inflammation in mice. In an ovalbumin mouse mode...
Article
Detailed numerical simulations have been performed to study the ignition behavior of hot spherical particles at atmospheric conditions. The particles move relative to a combustible gas with a velocity of 0–30 m s , which spans different flow regimes, from creeping flow to unsteady vortex shedding. The temperature of the particles’ surface increases...
Chapter
In this chapter the kinetics of underground coal gasification will be discussed. Underground gasification is characterized as a zonal process with time and space dependent state variables. This creates operating and boundary conditions for the different gasification processes, which cause changes in the reaction mechanisms and, hence, the kinetic r...
Chapter
In direct numerical simulation of turbulent combustion, the majority of the total simulation time is often spent on evaluating chemical reaction rates from detailed reaction mechanisms. In this work, an optimization method is presented for speeding up the calculation of chemical reaction rates significantly, which has been implemented into the open...
Article
The objective of the work is to validate the feasibility and the performance gain of a multi-regional approach, which has the potential to improve computing performance significantly for large-scale modelling of combustion processes. The basic idea is to solve the non-reactive, less CPU-intensive domain within the burner and the much more CPU-inten...