Pulse Detonation Engine Research Articles

Development of beam arrangement design for tunable diode laser absorption tomography reconstruction based on Tikhonov regularization parameter matrix

Beam arrangement with limited projections is a critical part of research on tunable diode laser absorption tomography reconstruction for combustion diagnosis. Based on the efforts to regularize this rank-deficient and ill-posed problem with Tikhonov regularization, a novel approach to using the regularization parameter matrix is developed for designing optical component layout and predicting the reconstruction accuracy. Objective function of beam arrangement is established by the rigorous mathematical derivation, and genetic algorithm is adopted to realize the optimization of function to overcome the difficulty associated with the multimodal nature of the problem. Nonuniform distribution properties of matrix elements in physical space relate to location and alignment of the laser/detector pairs, and form a basis for adjusting the weight between measurement and regularization to improve the reconstruction performance. A mathematical model of double Gauss distributions is established in a 10 × 10 element discrete tomography domain, and typically 20 measurement beams scanning the H<sub>2</sub>O transition at 7185.6 cm<sup>–1</sup> are available to probe the domain of interest. The systematic comparison between optimized beam array here and four existing beam arrangements in the literature is analyzed to validate the method. The reconstruction with Tikhonov regularization parameter matrix shows obvious advantages of reducing errors especially under the condition of fewer projections. The validation of reconstruction performance of the optimized beam array is also examined by simulating the laser absorption measurement which is carried out on phantoms generated using a simulation of external flow field of an air-gasoline pulsed detonation engine. The result shows that the optimized beam array consistently outperforms other arrangements reported in complicated fluid field. A demonstration reconstruction experiment is performed on the distribution from small gas burners. Both locations and amplitudes are in good agreement with those in the actual case. This proposed design method will be valuable in broadening the scope of applications of tunable diode laser absorption tomography reconstruction for engine diagnosis and combustion efficiency improvement.

Study of plasma-assisted detonation initiation by quasi-direct current discharge

To study the effects of quasi-direct current discharge plasma on the initiation of a pulse detonation engine at multiple locations, we proposed a double-zones quasi-direct current discharge plasma ignition scheme. Based on the establishment of the plasma-assisted detonation initiation model, the process of detonation wave formation in the mixture of hydrogen and air by single and double ignition zone were studied by numerical method. The wave structure, component evolution history, and Zeldovich–von Neumann–Döring curve after forming a stable detonation wave were all discussed. The simulation results indicate that due to its higher total ignition energy and the synchronous propagation of multiple compression waves, double-zone plasma ignition has a 17.9% shorter deflagration to detonation transition time and 14.2% lower detonation distance compared to the single-zone scheme. The double-zone scheme does not modify the peak flow field temperature and pressure when the stable detonation wave is formed, resulting in smoother pressure and temperature increases.

Technological advancements in Pulse Detonation Engine Technology in the recent past: A Characterized Report

Pulse Detonation Engine (PDE), is an emerging and promising propulsive technology all over the world in the past few decades. A pulse detonation engine (PDE) is a type of propulsion system that uses detonation waves to combust the fuel and oxidizer mixture. Theoretically, a PDE can be operate from subsonic to hypersonic flight speeds. Pulsed detonation engines offer many advantages over conventional air-breathing engines and are regarded as potential replacements for air-breathing and rocket propulsion systems, for platforms ranging from subsonic unmanned vehicles, long-range transportation, high-speed vehicles, space launchers to space vehicles. This article highlights the operating cycle of PDE, starting with the fuel-oxidizer mixture, combustion and Deflagration to detonation transition (DDT) followed by purging. PDE combustion process, a unique process, leads to consistent and repeatable detonation waves. This pulsed detonation combustion process causes rapid burning of the fuel-oxidizer mixture, which cannot be seen in any other combustion process as it is a thousand times faster than any other mode of combustion. PDE not only holds the capability of running effectively up to Mach 5 but it also changes the technicalities in space propulsion. The present paper is the extension of the previous study which is also a well characterized status report of PDE in different areas. The present study deals with the categorization of the design approach, computations & simulations, flow visualization, DDT & Thrust enhancement, PDRE’s, experimental detonation engines with some of the experience and research undertaken in Punjab Engineering College under the complete supervision and guidance of Prof. Tejinder Kumar Jindal followed by applications of PDE technology.

Analysis of Equivalence Ratio in an Oxygen Acetylene Mixture

The paper presents an exclusive approach to analyze the oxygen and acetylene mixture in a Pulse Detonation Engine setup at PEC. The experiment was carried out by varying the amount of mass flow of acetylene and oxygen into the tube at different pressures in the settling chamber. The equivalence ratio of the acetylene-oxygen mixture with respect to the valve opening time of acetylene and oxygen was plotted. The analysis of equivalence ratio also defines the procedure which involved the cycle of valves and pressure supply to attain different values of filling fraction of the tube. The results experimentally predicted the feasible range of operation at different pressures in the settling chamber of the pulse detonation engine.

Acoustic characteristics of pulse detonation engine sound propagating in enclosed space**Project supported by the National Natural Science Foundation of China (Grant Nos. 11372141 and 11472138), the Fundamental Research Funds for the Central Universities, China (Grant No. 30919011258), and the Young Scientists Fund of the Natural Science Foundation of Jiangsu Province, China (Grant No. BK20190439).

Acoustic characteristics of pulse detonation engine (PDE) sound propagating in enclosed space are numerically and experimentally investigated. The finite element software LS-DYNA is utilized to numerically simulate the PDE sound propagating in enclosed space. Acoustic measurement systems are established for testing the PDE sound in enclosed space, and the time-frequency characteristics of PDE sound in enclosed space are reported in detail. The experimental results show that the sound waveform of PDE sound in enclosed space are quite different from those in open space, and the reflection and superposition of PDE sound on the walls of enclosed space results in the sound pressure oscillating obviously. It is found that the peak sound pressure level (PSPL) and overall sound pressure level (OASPL) of PDE sound in enclosed space are higher than those in open space and their difference increases with the rise of propagation distance. The results of the duration of PDE sound indicate that the A duration of PDE sound in enclosed space is higher than that in open space except at measuring points located at 2-m and 5-m while the B duration is higher at each of all measuring points. Results show that the enclosed space has a great influence on the acoustic characteristic of PDE sound. This research is helpful in performing PDE experiments in enclosed laboratories to prevent the PDE sound from affecting the safety of laboratory environment, equipment, and staffs.

Numerical investigation of flame propagation in pulse detonation engine with variation of obstacle clearance

The objective of present research work is to investigate the combustion flame acceleration and performance of pulse detonation engine (PDE). The PDE tube consisting of obstacles of varying gap with fixed blockage ratio is analyzed in the current study. The three-dimensional reactive Navier–Stokes equation along with realizable k–e turbulence model is used to simulate the combustion phenomena of hydrogen–air mixture. The one-step irreversible chemical kinetics model analyzes detailed mechanism of exothermic reaction. The propagation of flame and deflagration-to-detonation transition (DDT) run-up length is based on normal propagating regime. As the gap between combustor inner surface and obstacle outer diameter increases, the propagating area near the combustor axis reduces. Therefore, loss of momentum of turbulence combustion particle and unburnt fuel particles (voids) are increased at the wake of obstacle due to the increase in gap (or reduction in obstacle outer diameter), which results reduction in detonation wave velocity and detonation total pressure. However, DDT flame run-up length increases with lower temperature along the axis of PDE combustor. The thrust force generated by PDE combustor also gets reduced as the obstacle diameter is reduced.

Effects of Various Compositions of the Fuel—Air Mixture on the Pulse Detonation Engine Performance

The objective of the present analysis is to investigate the effect of gaseous hydrocarbon fuels, such as Octane C8H18, Hexane C6H14, and Pentane C5H12 on the cyclic combustion process in an obstructed channel of the pulse detonation engine. Three-dimensional reactive Navier-Stokes equations are used to simulate the combustion mechanism of stoichiometric hydrocarbon fuels along with a one-step reaction model. The fuel is injected at atmospheric pressure and temperature and is ignited with pre-heated air. The investigation shows that initially a high-temperature combustion wave propagates with the local speed of sound; it creates turbulence after colliding with obstacles, resulting in an increase to supersonic flame speeds. Therefore, different values of the combustion flame propagation speed, combustion efficiency and impulse per unit area are obtained for these fuels. The detonation speed in the hexane-air mixture is about 5.8% lower than the detonation speed predicted by the NASA CEA400 code. However, it is observed that the octane fuel reduces the deflagration-to-detonation transition run-up distance as compared to other fuels.

Numerical investigation of flame propagation and performance of obstructed pulse detonation engine with variation of hydrogen and air

Pulse detonation engine is a new technique of supersonic wave propagation and stands for high impulsive thrust. The objective of the present investigation is to analyze the detonation wave characteristic of a hydrogen–air mixture in the pulse detonation engine (PDE) having obstacles of blockage ratio 0.5. The three-dimensional reactive Navier–Stokes equations with realizable k − ɛ turbulence model are used to simulate the propagation of combustion flame. The reaction rate of excess hydrogen and excess air is modeled by reduced single-step chemical reaction model and simulated using ANSYS software FLUENT 14.0 code. The simulation results of the shock wave overpressure, deflagration-to-detonation transition run-up distance of different flames and flame velocities are reported at initial boundary condition of 0.1 MPa pressure and 293 K temperature. It has been observed that the obstacles create turbulence in the propagating flame and form strong Mach stems of high temperature, resulting in reduction in accelerated flame run-up length. However, the normalized detonation flame run-up distance increases as the mass of fuel increases in the mixture. Thus, the performance of PDE combustor was observed 4.46% at high overpressure generated by excess fuel (ϕ = 1.3).

Study on the valveless and purgeless scheme to produce high frequency detonations in a long duration

High frequency and long duration operations are the ultimate objective for the considerable efforts in developing practical pulse detonation engines (PDEs). Previous works have demonstrated that the valveless and purgeless scheme has a great advantage in reducing the hardware complexity to achieve high frequency detonations. However, the great challenge arises in the implementation of long duration operation. Therefore, the present work aims at clarifying the key factor that significantly impacts the long duration of detonations. In this study, the detonation tube wall thickness, the type of obstacles for promoting the deflagration to detonation transition (DDT) process, and the closed end structure have been parametrically checked regarding their influence on the duration of detonations. The results from experiments showed that, although the wall thickness has little impact on the operating time, a conical diffuser properly designed is found to be able to greatly increase the operating frequency and improve the supply pressure ceiling, as a result of the creation of an efficient buffer zone. Actually, long duration detonations of 49 s at 90 Hz were achieved when the conical diffuser with a semi-angle of 5° was utilized. Finally, it is proposed that comprehensive cooling should be considered in long duration detonations.

Experimental study on the detonation process of a pulse detonation engine with ionized seeds

Abstract An experimental platform of a pulse detonation engine (PDE) was established to study the effect of different K2CO3 ionized seed mass contents on the detonation process. The pressure and ion concentration were detected in the detonation process of the PDE with different contents of ionized seeds. The initiation process of the PDE at different ignition frequencies was studied. The results show that the gas conductivity in the detonation process increased by adding ionized seeds to the PDE tube, and the conductivity increased with the increase in ionized seed mass content. With the increase in ionized seed mass content, the range of the conductivity decreased. The PDE was successfully ignited and formed a stable detonation wave at ignition frequencies of 5 Hz and 10 Hz, and the peak pressure of the stable detonation with the ignition frequency of 5 Hz was 17% higher than that with an ignition frequency of 10 Hz. The detonation wave intensity was weakened and degenerated to a shock wave that propagated in the tube without the fuel filled at the ignition frequency of 20 Hz.

Experimental research into the influence of two­spark ignition on the deflagration to detonation transition process in a detonation tube

The paper reports a study into the initiation of detonation in pulse detonation engines. The chosen direction to resolve this issue is the use of detonation tubes with multifocal ignition. We applied two spark discharges as a source of ignition, which ignited synchronously. The spark discharges were ignited at a distance, which provided for the intensive gas-dynamic interaction between the discharges. The interaction implied a collision between shock waves generated by the spark discharges. As a result, the growth in temperature of gas was ensured in the region between spark intervals, due to a collision between the oncoming shock waves.The influence of dual spark ignition on the time and length of the section where deflagration transfers into detonation along a detonation tube was studied by comparing the transition parameters for cases of single-spark and dual spark ignition all other conditions for research being equal. The study involved a detonation tube with a length of 2.3 m and an inner diameter of 22 mm. Spark plugs were located at the closed end of the tube. We applied a stoichiometric mixture of propane with oxygen, diluted with nitrogen by 50 % at the initial pressure in the mixture equal to 50 kPa. To register the time of propagation of the flame front and to measure the process rate, the tube was equipped with 22 ionization sensors. Distance between the sources of ignition was 6 mm. Length of the discharge interval at each source of ignition was 2.5 mm. Sources of ignition in the form of spark plugs were connected to high-voltage units with a total discharge energy of 3.3 J.The results of our study helped establish a reduction in the distance of deflagration to detonation transition by 1.6…2 times, and in the time of transition ‒ from 3.9 ms to 1.2 ms for the case of the transition from single-spark to dual spark ignition.The results obtained could be used when designing ignition systems for pulse detonation engines.

On the application of gas detonation-driven water jet for material surface treatment process

The recent advances in pulsed waterjet technology create new opportunities for developing green manufacturing process. New methods of generating pulsed water jets in a simple, controlled fashion are sought after to improve the efficiency of current techniques. This paper examines an unconventional concept for producing high-speed liquid jets, created by detonation phenomenon. The technique relies on harnessing the pressure gain from a detonative combustion to drive a piston that in turn propels a liquid jet at high speed. The proof-of-concept, together with recent pulsed detonation engine development, holds promising potential for detonation-driven pulsed water jet generation applied to manufacturing process.

Effects of an acoustic atomizer upon liquid-fueled detonation initiations in a detonation tube

The principle of a Hartmann-type acoustic nozzle is to generate ultrasonics to atomize the liquid fuel. Due to its outstanding performance on the atomization, the acoustic atomizer has been applied to internal combustion engine. Thus it possesses the potential to facilitate the liquid-fueled detonation initiations. In this paper, an acoustic atomizer was designed and established for a pulse detonation engine (PDE). The atomization characteristics and the flow pattern of the nozzle were analysed by a laser diffraction analyser and a high-speed camera. Multi-cycle detonation initiations experiments were conducted with the acoustic atomizer. The experimental results indicate that the performance of the nozzle was influenced by the air supply pressure, air-to-liquid fuel mass ratio and geometric parameters of the nozzle. The minimum Sauter mean diameter (SMD) measured was about 16 μm. The feasibility of the acoustic atomization scheme on cyclic detonation initiations was verified when the maximum operating frequency of the PDE reached 25 Hz. It suggests that the atomizer can effectively work under high-pressure condition in the detonation tube.

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Rationale for creating detonation CO2 laser for radioactive surface decontamination

The laser decontamination method is based on the evaporation of oxide films under the influence of radiation. With the evaporation mechanism, laser radiation should heat the upper layer of the film to the boiling point during the pulse and evaporate it. It is relevant because of the growing environmental requirements in the world, which makes it possible to create a compact, energy-efficient laser installation. Unlike existing energy-efficient laser units, the detonation laser system will significantly affect and quickly decontaminate radioactive surfaces due to the evaporation of oxide films under the influence of radiation. Detonation technologies are critical and can be used for pulse detonation systems, such as pulse detonation engines, detonation lasers, magnetohydrodynamic generators with detonation combustion of fuel, volume explosion initiation systems. The introduction of these systems in armaments and military equipment can substantially change the scope of their application. The average laser power can exceed 100 kW and above. At the same time, the use of the mixture as a power source makes the system not only compact, but also light in weight with respect to the existing similar systems. The wavelength will be 10.6 μm due to radiation in the far infrared region. That is, combined power plants will provide not only actuation, but also electric power supply of machines. This will allow the creation of power detonation units with a periodic initiation frequency of at least 100 Hz, which will work on a liquefied mixture and insignificant use of oxygen in the incendiary portion.

Semi-valveless pulse detonation cycle at a kilohertz-scale operating frequency

A high operating frequency of a pulse detonation engine is required to increase the thrust-to-engine weight ratio or thrust density. The semi-valveless pulse detonation cycle (PDC) proposed by Matsuoka et al. (2017) can achieve a high operating frequency exceeding several kilohertz. For achieving a higher operating frequency close to the upper limit of gas dynamics, it is necessary to minimize the process in which the buffer layer is applied to avoid self-ignition of the detonable mixture. Experiments were conducted, and a one-dimensional numerical model was developed to investigate the minimum thickness of the buffer layer and the required duration for the stable PDC operation. Ethylene was used as a fuel and pure oxygen as an oxidizer. The total length of two combustors with an inner diameter of 10 mm was 40 and 80 mm. Therefore, the thickness of the buffer layer of approximately 20 mm was suggested for the stable PDC operation. This result indicated that 10% of the duration of one PDC was required to prevent self-ignition (SI). In the failed PDC, the early and late SI were confirmed. Interestingly, high-frequency PDC operation with a short combustor can suppress late SI and results in a higher success rate with the same thickness of the buffer layer. Furthermore, a stable PDC operation of a 1916 Hz with a combustor with a total length of 40 mm was demonstrated.

Combustion characteristics of hydrogen-air mixture in pulse detonation engines

The literature review reveals that the supersonic combustion wave remains a helpful method for improving the efficiency of pulse detonation engines (PDEs). A number of experimental studies have been conducted on detonation waves, which are formed by deflagration-to-detonation (DDT) transition waves. In this work, a straight PDE tube with a length of 1200 mm and a circular cross section measuring 60 mm in diameter is considered for combustion analysis. The combustion mechanism of stoichiometric hydrogen-air mixture is modeled by a three-dimensional Navier-Stokes turbulence model with a one-step reduced chemical kinetic reaction model using ANSYS Fluent software. The detonation tube contains obstacles with various blockage ratios of 0.5, 0.6 and 0.7 with 60 mm spacing (S) between them. Initial boundary conditions of 0.1 MPa pressure and 293 K temperature are applied to the hydrogen-air mixture to initiate combustion. The objective of the present work is to analyze the combustion flame generation and development of a stable detonation wave in the PDE tube. The flame rapidly develops and accelerates due to the burning of unburnt fuel particles in the leading zone and reduces the DDT run-up length.

Design of Online Monitoring System for Pulse Detonation Engine

The PDE monitoring equipment being applied is large in size, harsh in working conditions, unable to carry out outdoor experiments, limiting the flexibility of PDE’s original rational experiment. An online monitoring system was designed to meet needs of mobility, real-time, portability, none effect on PDE thrust test and so on. The paper introduces the whole scheme of the online monitoring system, the hardware design of each function module and the software design of the whole scheme. The experimental results show that the on-line monitoring system can realize the measurement of working parameters in the principle experiment of pulse detonation engine in time and accurately and improve the flexibility of operation

Numerical Investigation of Combustion Wave Propagation in Obstructed Channel of Pulse Detonation Engine using Kerosene and Butane Fuels

Numerical Investigation of Combustion Wave Propagation in Obstructed Channel of Pulse Detonation Engine using Kerosene and Butane Fuels

Numerical investigation of the liquid-fueled pulse detonation engine for different operating conditions

In this study, an intensive simulation platform is developed and implemented to simulate the three stages in the operational cycle of the liquid-fueled pulse detonation engine. The three stages encompass the liquid fuel injection and evaporation process, deflagration-to-detonation transition process, and detonation propagation process. The Lagrangian–Eulerian approaches are employed to model the discrete liquid fuel droplets and the continuous vapor phase, respectively. The breakup and evaporation of liquid droplets are modeled using sub-models, while the interactions between the liquid droplets and the vapor phase are expressed through the two-way interaction models. The Jet-A liquid fuel is injected into the detonation chamber as the fuel for the engine, while the air flow is used as the oxidizer. A reduced chemical kinetic model of fuel/air is used to model the combustion process. The simulation platform is systematically validated against the experimental data for every stage of the operating cycle. To study the influence of the inlet and operating conditions, the numerical simulations are performed for three different operating conditions, which are the change in inlet air temperature, the change in inlet air flow velocity, and the change in liquid fuel mass flow rate. The obtained results indicate that the mass fraction of pre-vaporization of fuel plays an important role in the successful DDT process and/or detonation onset. The deflagration can successfully transit to detonation for both the cases of complete and incomplete vaporization of the liquid droplets inside the detonation chamber. The deflagration cannot successfully transit to detonation for the case of too lean or too rich fuel vapor in the mixture. The calculated burning temperature and Chapman–Jouguet (C–J) detonation velocity are slightly lower in the cases of the incomplete vaporization when compared to the complete vaporization cases. In addition, our numerical results show that the burning process occurs in two stages in the incomplete vaporization case: The first burning stage plays a main role in the successful DDT process, while the second burning stage only plays the role of augmentation.