Numerical Investigation of Combustion Wave Propagation in Obstructed Channel of Pulse Detonation Engine using Kerosene and Butane Fuels (original) (raw)
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Numerical Investigation of Detonation Wave Propagation in Pulse Detonation Engine with Obstacles
SSRN Electronic Journal, 2019
The numerical investigation of Detonation wave propagation and Deflagration-to-Detonation transition is done in straight long tube of 1200 mm length and 60 mm internal circular diameter with stoichiometric (ϕ=1) mixture of hydrogen-air at ambient pressure and temperature of 0.1 MPa and 293 K respectively. The detonation tube contains obstacles having blockage ratio (BR) 0.5, 0.6 and 0.7, and having 60 mm gap among them. The computation analysis is performed firstly on simple straight tube having no obstacle (BR=0.0) and then obstructed channel. The combustion phenomena of fuel-air mixture are modeled by one-step irreversible chemical reaction model. Three-dimensional Navier-Stokes equations along with realizable k-ɛ turbulence model are solved by the commercial computation fluid dynamics software ANSYS Fluent-14 code. The performance of pulse detonation engine (PDE) depends on blockage ratio (BR) of obstacles. The simulation results show that the initiation and propagation of flame is due to exothermic expansion of hot combustion gases. The obstacles generated turbulence at obstacle wakes, which caused to increase flame surface area. Therefore, obstacles reduced the Deflagration-to-Detonation transition (DDT) run-up length. The perturbation inside the combustor increases as increased the blockage ratio of obstacle. The PDE Simulation results of with and without obstacles were analyzed and compared with adiabatic flame temperature.
Pulse detonation technology can be a revolutionary approach for propulsion system since it offers significant fuel efficiency, higher thrust to weight ratio and low cost. Although the design concept of a pulse detonation engine is comparatively simple, but the development and stabilization of sustainable detonation wave front is difficult. Consequently pulse detonation engine technology is still in active research stage. To accelerate the development of pulse detonation engine, there is a need to carefully pursue the experimental analysis of pulse detonation engine. At the same time, numerical simulation is equally important to understand the detonation phenomena in the PDE combustor. This paper deals with the numerical modeling and simulation of PDE tube with Hydrogen-Air mixture by using a commercially available CFD code. Pulse detonation engine combustor with and without obstacle has been numerically simulated. Simulation results of PDE combustor with and without obstacles have been analyzed and compared. The simulation results revealed the formation of reflection waves when the detonation wave interacted with the obstacles. The simulation results provided valuable insight into the interaction between detonation wave and obstacles which will be ultimately useful for design and development of pulse detonation engine combustor.
Effects of Various Compositions of the Fuel—Air Mixture on the Pulse Detonation Engine Performance
Combustion, Explosion, and Shock Waves, 2019
The objective of the present analysis is to investigate the effect of gaseous hydrocarbon fuels, such as Octane C 8 H 18 , Hexane C 6 H 14 , and Pentane C 5 H 12 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.
Performance characteristics of combustion and emission in pulse detonation engine
A shift in combustion concepts from conventional isobaric to constant volume combustion (CVC) has various benefits. Pulse detonation combustion (PDC) works on CVC, significantly increasing the engine's thermodynamic efficiency. Pollutant emissions from pulse detonation engines (PDE) have received little research. PDE has higher temperature combustion, resulting in a higher NOx emission. In the present paper, the formation of NOx is investigated using the computational fluid dynamics (CFD) method. A model is constructed by varying pressure, temperature, spark size, and geometry for hydrogen fuel. SST K- Omega model with transient conditions is used. CFD analysis was performed to calculate EINOx for 12 cm and 20 cm tubes. Encouraging results were obtained. The size of 12 cm tube produced EINOx of 200 g/kg of fuel, and a 20 cm tube produced 250 g/kg of fuel. Computed results are in good agreement with previous literature.
Numerical Investigation of Detonation Combustion Wave in Pulse Detonation Combustor With Ejector
2017
Detonation combustion based engines are more efficient compared to conventional deflagration based engines. Pulse detonation engine is the new concept in propulsion technology for future propulsion system. In this contrast, an ejector was used to modify the detonation wave propagation structure in pulse detonation engine combustor. In this paper k-ε turbulence model was used for detonation wave shock pattern simulation in PDE with ejectors at Ansys 14 Fluent platform. The unsteady Euler equation was used to simulate the physics of detonation wave initiation in detonation tube. The computational simulations predicted the detonation wave flow field structure, combustion wave interactions and maximum thrust augmentation in supersonic condition with ejectors at time step of 0.034s. The ejector enhances the detonation wave velocity which reaches up to 2226 m/s in detonation tube at same time step, which is near about C-J velocity. Further the time averaged detonation wave pressure, temperature, wave velocity and vortex characteristics interaction are obtained with short duration of 0.023s and fully developed detonation wave structures are in good agreement with experimental shadowgraph, which are cited from previous experimental research work.
Combustion characteristics of hydrogen-air mixture in pulse detonation engines
Journal of Mechanical Science and Technology, 2019
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 deflagrationto-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.
2020
Propulsion based engines have been known for their exemplary thrust but also for lower fuel efficiency and speed of operation which is limited to subsonic and the level of intermittent vibrations produced. Pulse Detonation Engine (PDE) is similar to a Pulse Jet Engine (PJE) except for the fact that the flame formed inside the combustion chamber of PDE travels at supersonic speed, whereas in PJE, it is subsonic. The supersonic speed of flame front in PDE is because of the detonation wave formed during the combustion of the fuel mixture which is in the order of 2000 m/s and is based on constant volume combustion. A process called Deflagration to Detonation Transition (DDT) can be used for which turbulence has to be created inside the combustion chamber. The obstacles used in this study were vortex generators and the CAD model of the engine and the obstacles assembly was made in SOLIDWORKS 19.0 software. ANSYS (FLUENT) 16.0 was used for the simulation of the combustion inside the combustion chamber using the Species Transport Model for the performance evaluation.
Investigation of Transition of Deflagration to Detonation in Moving Mixtures of Combustible Gases
In the report the new experimental data about essential reduction of predetonation distance are presented in the case of detonation initiation with an weak electric discharge in a detonable gas flow. Experiments were done at the device, which allows modeling one cycle of pulse detonation engine operation. The experimental data are compared to the results of numerical calculations. The good consent with experiments demonstrates feasibility of the offered methods of calculations and allows to give explanation to the observed experimental effects. The results seem to be of practical application to the control of detonation process in PDE.
AN EXPERIMENTAL STUDY ON KEROSENE BASED PULSE DETONATION ENGINE
The paper summarizes the experimental study on kerosene based pulse detonation engine in a tube for three different equivalence ratios. The kerosene was vaporized in a pre-evaporator before injected into combustion chamber. Pre-heated air was injected through a nozzle into the detonation tube. The charged tube was electrically ignited near the injector end. To enhance the DDT and to reduce the transition distance Shchelkin spiral was used inside the tube. Comparison of measured pressure at different locations of the tube with the CEA values were made that confirms to have crossed the CJ point and provide a stable detonation.