Pulse Detonation Engine Research Articles

Characterization of Shock Wave Transfer in a Pulse Detonation Engine–Crossover System

Shock wave propagation within a pulse detonation engine–crossover system is investigated, examining the properties and mechanisms of the transfer process. A shock wave is transferred through a crossover tube that connects a spark-ignited driver pulse detonation engine to a secondary, driven pulse detonation engine. Detonations in the driven pulse detonation engine develop from shock-initiated combustion, as strong shock wave reflection can cause ignition within a reactive mixture. A pulse detonation engine–crossover system can decrease deflagration-to-detonation transition length while employing a single spark source to initiate a system consisting of multiple detonation engines. Visualization of a shock wave propagating through a clear channel reveals a complex shock train behind the leading shock wave. Transverse waves connect with the leading shock wave to form a triple point that oscillates through the leading shock wave. The shock wave Mach number and decay rate remain constant for varying crossover tube geometries and operational frequencies. A temperature gradient forms within the crossover tube due to forward flow of high-temperature ionized gas into the crossover tube from the driver pulse detonation engine and backward flow of ionized gas into the crossover tube from the driven pulse detonation engine. This communication results in intermittent autoignition of the driver pulse detonation engine for higher-frequency large-crossover-tube-diameter cases. However, small-diameter crossover tubes prevent these autoignition events at higher frequencies.

Experimental investigation on detonation combustion patterns of hydrogen/vitiated air within annular combustor

Experiments on continuous rotating detonation (CRD) were performed using hydrogen and vitiated air with total temperature of 860K. Two types of detonation phenomenon were found, namely, continuous rotating detonation wave (CRDW) traveling azimuthally in the annular detonation combustor, and detonation wave (DW) propagating along the detonation combustor axial direction. For the CRDW, four different combustion patterns existed, namely, one wave in homo-rotating mode, two waves in homo-rotating mode, one couple in hetero-rotating mode and two couples in hetero-rotating mode. For DW propagating axially, it was like pulse detonation engine (PDE), but do not need repeated ignition. Besides, the DW propagated upstream, and worked with a higher frequency than PDE. The experiments showed that the DW could be sustained continuously and steadily in all the five patterns within annular combustor, requiring no repeated ignition.

Schlieren imaging and pulsed detonation engine testing of ignition by a nanosecond repetitively pulsed discharge

A nanosecond repetitively pulsed (NRP) discharge in the spark regime has been investigated as to its effectiveness in reducing ignition time, both in a flow tube and a pulsed detonation engine (PDE). The flame-development time for methane–air mixtures in the flow tube is found to be a function of the total ignition energy and the pulse repetition frequency. Schlieren imaging revealed that at low pulse-repetition frequency (0–5kHz), ignition kernels formed by the discharge are each transported away from the discharge gap before the following pulse arrives. At higher pulse-repetition frequencies (⩾10kHz), multiple pulses are all coupled into a single ignition kernel, thus the resulting ignition kernel size and the total energy deposition into the kernel are increased, resulting in a faster transition into a self-propagating flame. Imaging of the NRP discharge in air revealed that at high pulse frequencies (>10kHz) and peak pulse amplitude (>9kV), the plasma emission is not quenched in-between pulses, resulting in a building up of heat and radicals in the center of the ignition kernel. Optical emission spectra revealed the presence of electronically excited N2, O, and N, as well as O+ and N+, during and between the discharge pulses. Numerical modeling of the plasma indicated that reactions of excited species mainly lead to the production of O atoms and the increase of gas temperature, which shortens induction chemistry timescales, and thus reduces the flame-development time through both kinetic and thermal mechanisms. Ignition of aviation gasoline–air mixtures by NRP discharge in a PDE also demonstrated a noticeable reduction in ignition time as compared to an automotive aftermarket multiple capacitive-discharge ignition system.

A Target Indirect Thrust Measurement Method of Pulse Detonation Engine

AbstractAn indirect thrust measurement method based on impulse of a target plate was developed, and a new thrust measurement system (TMS) was successfully designed and constructed. A series of multi-cycle experiments on thrust measurement were conducted to investigate the feasibility of this method with the newly-built indirect TMS. The thrust measurement of PDE was made at different plate target axial positions and operating frequencies. All the experiments were conducted using gasoline as fuel and air as oxidant. The experimental results implied that the thrust of PDE by using the indirect impulse method was a function of the target plate axial position, and there existed an optimum measurement position for PDE with a diameter of 60 mm. The optimum target plate position located at 3.33. According to the experimental results, the thrusts obtained by using indirect TMS were less than the actual values, and so the observed value of thrust was modified in order to make the thrust more reliable. A relative accurate calibration formula depending on the operating frequency was found.

Experimental investigation of thrust augmentation by ejectors on a pulse detonation engine

Utilizing gasoline as the fuel, air as oxidizer, a series of multi-cycle detonation experiments was conducted to study thrust augmentation by PDE-driven ejectors. The straight cylindrical ejectors with different inner diameter, length and inlet geometry were designed. The effects of the axial location of the ejectors relative to the end of the detonation tube, ejector length-to-diameter ratio on thrust augmentation were investigated, with the operating frequency of 25 Hz. A peak thrust augmentation level of 80.5% was achieved by adding an ejector to the exit of the detonation tube. Performance measurements of the PDE-ejector system showed that thrust augmentation is a strong function of the ejector axial position. The result indicated that there exists a maximum thrust augmentation with ejector upstream of the detonation tube exit at least. The exact location at which the maximum thrust augmentation was obtained varies with the ejector-to-PDE diameter ratio and the ejector inlet geometry. With the increase of the length-to-diameter ratio, thrust augmentation was noticeably enhanced and finally tended to a constant. There exists an optimum ejector length. In the present study, the optimum length-to-diameter ratio of ejector was 4.58. Furthermore, the effect of operating frequency on ejector thrust augmentation also investigated. The operating frequency was varied from 15 Hz to 35 Hz.

Numerical Studies of Multi-cycle Acetylene-air Detonation Induced by Shock Focusing

Shock focusing techniques can avoid deflagration-to-detonation transition (DDT), which make PDE more efficiency. Numerical simulations of an idealized pulse detonation engine consisting of axial inlet and circumferential inlet are presented in this paper. Using detailed acetylene-air chemical kinetic model, investigation on detonation direct initiation by shock focusing is done. Studies indicate that in static flow field, the regions of high temperature and pressure created by shock focusing can produce detonation at the condition of circumferential inlet Mach 2.4. But in dynamic flow field, Mach number should increase to 3.5 to achieve detonation

Multicriterial choice of the best variant of the pulse detonation engine design for aircraft angular stabilization and orientation systems

The verbal and mathematical formulations of the problem of multicriterion ranging of the pulse detonation engine design variants were carried out. Using the method of morphological box the morphological tablewas composed, on the basis of which many possible design variants of the pulse detonation engines were generated.When compiling the morphological table a conception of pulse detonation engines in the form of the followingsubsystems was considered: detonation chamber, components supply system, initiation system, controlsystem. Eventually as valid options, which were subjected to a study on the firing test bench, we selected twentyvariants. The system of criteria for the assessment of the pulse detonation engines design variants (specificthrust, frontal thrust, specific consumption, unit weight, length) was proposed. Criteria values were determinedduring firing tests. The peculiarities of solving problems by using the methods of "hard" ranging, hierarchiesanalysis, Borda`s method were discovered. The criterion formation of the true Pareto tuples was formulated. Usingthe methods of "hard" ranging, hierarchies analysis, Borda`s method, the criterion of the true Pareto tuplesformation the applied problems of choosing the best pulse detonation engine variant for three important caseswere resolved: - the atmosphere is taken into account, pulse detonation engine suffers the influence of the frontalresistance; - the atmosphere is taken into account, pulse detonation engine is located inside the aircraft and doesnot suffer the immediate impact of the frontal resistance; - the influence of the atmosphere is not taken into account,only pulse detonation engines without ejector are subject to the analysis. The best pulse detonation enginedesign variants for different values of the criteria priorities were revealed.

Finite element simulation of gaseous detonation-driven fracture in thin aluminum tube using cohesive element

Detonation-driven fracture problems in tube under dynamic load have received plenty of attention because of various ranges of applications, such as oil and gas pipeline systems, new rocket engine such as pulse detonation engine, and pressurized aircraft fuselages. This paper reports the crack growth modeling in a thin aluminum tube under gaseous detonation load. Because of three-dimensional fracture dynamics with gas dynamics coupled phenomena, analytical modeling is complicated. Thus, a finite element method was applied. The finite element modeling and simulation of the tube under detonation moving load were performed using commercial code Abaqus. This simulation leads to obtain structural response of the tube to detonation load. The simulations were compared with experimental and analytical results from the literature for elasto-dynamic response of cylindrical shells with finite length under internal detonation loading. Cohesive element with traction–separation law was used for crack growth modeling along with crack tip opening displacement value obtained from experimental–numerical analysis from previous research. The final section of the paper is dedicated to investigating differences and comparisons between the numerical crack propagation simulations and experimental results reported in the literature. It has been demonstrated that using cohesive elements with some modifications can improve the numerical accuracy. The obtained results are more similar to the experimental results than numerical results available in literature.

Parametric Cycle Analysis of an Ideal Pulse Detonation Engine

The purpose of this work is to present a mathematical description of an ideal pulse-detonation-engine-based on parametric cycle analysis. The parametric cycle analysis is presented in terms of parameters similar to those for the well-known parametric cycle analyses for the ideal turbojet engine and the ideal ramjet engine. The performance characteristics of specific thrust, thrust-specific fuel consumption, fuel-to-air ratio, thermal efficiency, propulsive efficiency, and overall efficiency are presented as functions of the two variables: compressor total pressure ratio and freestream flight Mach number . This work provides algebraic equations that can be used conveniently to investigate the ideal pulse detonation engine performance as a function of a variety of input parameters. It is hoped that this work will aid in exploring the performance of the ideal pulse detonation engine from a big-picture perspective.

3D versus 2D calculation of thrust characteristics of the air-breathing pulse detonation engine under supersonic flight conditions

3D calculations are used to confirm the conclusion that the specific thrust of the air-breathing pulse detonation engine is 20–30% higher than that of the ideal ramjet in which normal combustion takes place.

PDE 기반 PGC 추진기관 시스템 연구 동향

대부분의 항공우주 추진은 정압 Brayton 사이클에 기초하고 있으나 성능 향상을 위한 압력비 증가는 기계적 한계에 직면하고 있다. 지난 십여 년간 고속 추진에 적합한 연소방식으로 기대 받은 데토네이션 추진이, 최근에는 추진기관과 동력 장치의 열효율을 획기적으로 증대시켜 줄 수 있는 "game-changer"로 연구되고 있다. 즉, 데토네이션 파에 수반하는 강한 충격파의 압축 효과는 기존의 압축 방식에서 얻기 힘든 열효율을 증가시키는 것으로 여겨진다. 본 논문에서는 펄스데토네이션엔진의 최신 기술 동향과 더불어 정적연소에 기초한 압력증가연소 체계의 연구 동향에 대하여 소개할 것이다. Most of the aerospace propulsion is based on the Brayton cycle, in which the combustion is held through the constant pressure process, but further improvement of performance by increasing compression ratio is challenged by mechanical limits. Detonation propulsions, regarded promising for high-speed propulsion for a lase decade, is more rigorously studied in these days as a game-changer for the improvement of thermodynamic efficiency of propulsion and power generation systems. Since, the additional compression by the strong shock of the detonation wave is considered increasing thermodynamics efficiency that is hardly achievable by the conventional compression systems. Present paper will give an introduction the latest technical trends on the Pulse Detonation Engines(PDEs) and the activities on the Pressure Gain Combustion (PGC) based on Constant Volume Combustion (CVC).

Experimental Validation of Effect Of Equivalence Ratio on Detonation Characteristics of Propane/Oxygen Mixtures

Experimental studies were carried out for using Propane as fuel for Pulse Detonation Engine application. In the present study Detonation Characteristics of Propane & Oxygen mixture at various equivalence ratios were presented. In these experiments Propane and Oxygen under regulated pressures were injected into a Detonation Tube from the head end using unlike impinging doublet injector. The fuel and oxidizer were allowed to mix and fill the tube. Subsequently, the mixture was ignited using a spark plug positioned close to the head end of the tube. The pressures generated due to the combustion of the mixtures were captured using five high frequency pressure transducers which were spaced 100mm apart on the detonation tube. Apart from these pressures, velocities of the combustion wave were computed using ‘time of flight’ method. These tests were done for different equivalence ratios varying from 0.8 to 1.6 by varying the feeding pressure of Propane. In the present study the performance of the combustion wave at different locations and effect of equivalence ratios on detonation characteristics were presented. In addition effect of presence of obstacles in the flow path i.e., Shchelkin spirals were also studied in reducing the Deflagration to Detonation Transition (DDT) distance.

Experimental investigation on the operating characteristics in a multi-tube two-phase valveless air-breathing pulse detonation engine

A four-tube two-phase gasoline/air valveless air-breathing pulse detonation engine (PDE) was designed and tested to investigate the operating characteristics of multi-tube air-breathing PDE. The PDE was operated at a maximum frequency of 30 Hz per tube with a total maximum frequency of 120 Hz. Four different firing patterns were successfully carried out: single tube firing, dual tubes firing simultaneously, three tubes firing simultaneously, and four tubes firing simultaneously. The synchronicity of the detonation waves and back-propagation pressure waves under multi-tube firing patterns were quantified and compared. The averaged peak pressure of back-propagation pressure waves in the air plenum chamber was discussed. The experimental results indicated that the four-tube PDE could be operated successfully under the four firing patterns and transformed from one firing pattern to another. The time of arrival differences of detonation waves showed up in all multi-tubes firing patterns, which led to greater arrival differences of back-propagation pressure waves. The averaged peak pressure of back-propagation pressure waves in the air plenum chamber had the same change trend under multi-tube firing patterns. Single tube firing pattern resulted in the smallest pressure peak in the air plenum chamber and the pressure peak increased at the increased fired tubes.

Shock Transfer and Shock-Initiated Detonation in a Dual Pulse Detonation Engine/Crossover System

An experimental investigation was carried out to study the propagation of a shock wave through a crossover tube for the purpose of causing shock-initiated detonation. A pulse detonation engine was used as a driver source to propagate a shock wave through a crossover tube into a second, adjacent detonation tube (that is, driven). Results showed a transferred shock wave achieved shock-initiated detonation, and for specific crossover tube geometries, there was a maximum effective crossover tube length for which the event was possible. This maximum effective length was strongly correlated to the strength of the transferred shock. Initiation performance in the driven detonation tube declined when the incident shock strength decreased below . Introducing a bend to the end of the crossover tube increased the driven detonation tube initiation performance by enhancing the strength of the transferred planar shock wave by an average of 20%. A numerical investigation on shock wave planar attenuation in a crossover tube corroborated the experimental results.

Thrust measurement method verification and analytical studies on a liquid-fueled pulse detonation engine

In order to test the feasibility of a new thrust stand system based on impulse thrust measurement method, a liquid-fueled pulse detonation engine (PDE) is designed and built. Thrust performance of the engine is obtained by direct thrust measurement with a force transducer and indirect thrust measurement with an eddy current displacement sensor (ECDS). These two sets of thrust data are compared with each other to verify the accuracy of the thrust performance. Then thrust data measured by the new thrust stand system are compared with the verified thrust data to test its feasibility. The results indicate that thrust data from the force transducer and ECDS system are consistent with each other within the range of measurement error. Though the thrust data from the impulse thrust measurement system is a litter lower than that from the force transducer due to the axial momentum losses of the detonation jet, the impulse thrust measurement method is valid when applied to measure the averaged thrust of PDE. Analytical models of PDE are also discussed in this paper. The analytical thrust performance is higher than the experimental data due to ignoring the losses during the deflagration to detonation transition process. Effect of equivalence ratio on the engine thrust performance is investigated by utilizing the modified analytical model. Thrust reaches maximum at the equivalence ratio of about 1.1.

Numerical study of the processes of resonance emergence in the experimental set-up of a pulse detonation engine

The results of calculations of the pressure, flow rate, and temperature in the combustion chamber of a pulse detonation engine (PDE) for the conditions realized in the experiment are presented. On the basis of the developed mathematical model, the multiparameter calculations are performed for physical processes occurring in the working path of a PDE. We studied the conditions for the occurrence of oscillations in the PDE combustion chamber. For certain values of the parameters of the set-up, the oscillations have constant amplitude and frequency. These results are in good agreement with the data of other authors. The conditions under which the detonation engine can operate in the pulse mode are also investigated in the paper.

A technique for promoting detonation transmission from a confined tube into larger area for pulse detonation engine applications

A simple method of detonation transmission from a small tube to a large area is presented. This technique involves placing obstacles which create slight blockages at the exit of the confined tube before the planar detonation emerges into the larger space, thereby generating flow instability to promote the detonation transmission. In this experimental study two mixtures of undiluted stoichiometric acetylene-oxygen and acetylene-nitrous oxide are examined. These mixtures can be characterized by a cellular detonation front that is irregular and representative of those potentially used in practical aerospace applications. The blockage ratio imposed by the obstacles is varied systematically to identify the optimal condition under which a significant reduction in critical pressure for transmission can be obtained. A new perturbation configuration for practical use in propulsion and power systems is also introduced and results are in good agreement with those obtained using thin needles as the blockage ratio is kept constant.

One-dimensional unsteady design method for pulsed detonation engine nozzles

A new design method for pulse detonation engines nozzle was developed theoretically. The effects of non-uniform exhaust on the performance of pulse detonation engine were analyzed by constant volume cycle model. The results showed thrust losses induced by the non-uniform exhaust could be decreased by increasing fill pressure ratio. If the fill pressure ratio was larger than 10, the performance losses with a fixed optimal nozzle could be controlled within 3%. The optimal area ratio of the nozzle was obtained when the time-averaged pressure at the nozzle exit equals the ambient pressure. This was also applicable to one-dimensional unsteady frictionless pulse detonation engine model. Thus an optimal area of the nozzle could be calculated by the time-averaged total pressure. Compared with the zero-dimensional results obtained by numerical search technique, the errors of predicted optimal area could be neglected if fill pressure ratio is too large to prevent shock from propagating back to the nozzle. And the errors of predicted optimal area are lower than 5% compared with the results of the one-dimensional unsteady pulse detonation engine model.

Energy Loss in Pulse Detonation Engine due to Fuel Viscosity

Fluid viscosity is a significant factor resulting in the energy loss in most fluid dynamical systems. To analyze the energy loss in the pulse detonation engine (PDE) due to the viscosity of the fuel, the energy loss in the Burgers model excited by periodic impulses is investigated based on the generalized multisymplectic method in this paper. Firstly, the single detonation energy is simplified as an impulse; thus the complex detonation process is simplified. And then, the symmetry of the Burgers model excited by periodic impulses is studied in the generalized multisymplectic framework and the energy loss expression is obtained. Finally, the energy loss in the Burgers model is investigated numerically. The results in this paper can be used to explain the difference between the theoretical performance and the experimental performance of the PDE partly. In addition, the analytical approach of this paper can be extended to the analysis of the energy loss in other fluid dynamic systems due to the fluid viscosity.

Influencing Factors on the Performance of Pulse Detonation Engine at Test Bench

Unsteady operation of valveless pulse detonation engine results in unsteady gas dynamics of air inflow. In this paper, a simplified model has been developed to evaluate actual performance of pulse detonation engine with consideration of intake condition. The volume of plenum chamber, inflow area of pulsed detonation chamber and the operation frequency are considered as influencing factors on pulsed detonation chamber thrust performance. The simulation results show bigger plenum chamber volume leads to less inflow perturbation of pulsed detonation chamber. If the gas state of inflow is not determined by unsteady character, the negative thrust of pulsed detonation chamber will decrease with the increase in frequency. But when unsteady character has an effect on inflow, the negative thrust of pulsed detonation chamber increases with the increase in frequency. The experimental results of pulse detonation engine on test bench confirmed the simulation results.