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Papers by Dr. PINKU DEBNATH

Springer Nature, 2020

The detonation combustion phenomenon is supersonic combustion process and follows on thermal expl... more The detonation combustion phenomenon is supersonic combustion process and follows on thermal explosion in combustor. Deflagration to detonation transition occurs in detonation tube due to pressure oscillation in PDE combustor, which is driven by acoustic combustion phenomena in detonation tube. As this combustion process has great significance role for future propulsion system, the present objective is to investigate the effect of modify ejector having half angles of α = (− 4°, 0°, + 4°) on detonation combustion wave propagation regime. Further the propulsion thrust of liquid kerosene and gaseous hydrogen–air mixture are also analyzed. This numerical simulation has been analyzed by LES turbulence model for DDT and shock wave pressure oscillation in pulse detonation combustor at Fluent based CFD plat form. The one-step irreversible chemical kinetics model analyzes the details exothermic chemical reaction mechanism inside the combustor. However, the shrouded ejector with taper angle of α = +4° performed the strong starting vortex generation and shortest possible time of 0.032 s for fully developed detonation wave. The simulation results also shows that thrust force augmentation of hydrogen–air mixture is greater compared to combustion process of liquid kerosene–air mixture with significant magnitude of 38 N. Although kerosene–air mixture produces less pollutant number but the propagation flame velocity is 2550 m s−1 for hydrogen/air mixture, which is near about C–J velocity and comparatively higher than kerosene/air combustion process.

Detonation combustion based engines are more efficient compared to conventional deflagration base... more 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.

Exergy losses during the combustion process, heat transfer, and fuel utilization play a vital rol... more Exergy losses during the combustion process, heat transfer, and fuel utilization play a vital role in the analysis of the exergetic efficiency of combustion process. Detonation is thermodynamically more efficient than deflagration mode of combustion. Detonation combustion technology inside the pulse detonation engine using hydrogen as a fuel is energetic propulsion system for next generation. In this study, the main objective of this work is to quantify the exergetic efficiency of hydrogen–air combustion for deflagration and detonation combustion process. Further detonation parameters are calculated using 0.25, 0.35, and 0.55 of H 2 mass concentrations in the combustion process. The simulations have been performed for converging the solution using commercial computational fluid dynamics package Ansys Fluent solver. The details of combustion physics in chemical reacting flows of hydrogen–air mixture in two control volumes were simulated using species transport model with eddy dissipation turbulence chemistry interaction. From these simulations it was observed that exergy loss in the deflagration combustion process is higher in comparison to the detonation combustion process. The major observation was that pilot fuel economy for the two combustion processes and augmentation of exergetic efficiencies are better in the detonation combustion process. The maximum exergetic efficiency of 55.12%, 53.19%, and 23.43% from deflagration combustion process and from detonation combustion process, 67.55%, 57.49%, and 24.89%, are obtained from aforesaid H 2 mass fraction. It was also found that for lesser fuel mass fraction higher exergetic efficiency was observed.

Pulse detonation engines (PDEs) are new exciting propulsion technologies for future propulsion ap... more Pulse detonation engines (PDEs) are new exciting propulsion technologies for future propulsion applications. The operating cycles of PDE consist of fuel-air mixture, combustion, blowdown, and purging. The combustion process in pulse detonation engine is the most important phenomenon as it produces reliable and repeatable detonation waves. The detonation wave initiation in detonation tube in practical system is a combination of multistage combustion phenomena. Detonation combustion causes rapid burning of fuel-air mixture, which is a thousand times faster than deflagration mode of combustion process. PDE utilizes repetitive detonation wave to produce propulsion thrust. In the present paper, detailed review of various experimental studies and computational analysis addressing the detonation mode of combustion in pulse detonation engines are discussed. The effect of different parameters on the improvement of propulsion performance of pulse detonation engine has been presented in detail in this research paper. It is observed that the design of detonation wave flow path in detonation tube, ejectors at exit section of detonation tube, and operating parameters such as Mach numbers are mainly responsible for improving the propulsion performance of PDE. In the present review work, further scope of research in this area has also been suggested.

Detonation is the supersonic mode of combustion process which is essential for energy release fro... more Detonation is the supersonic mode of combustion process which is essential for energy release from combustion process. Detonation is the more energetic process compare to deflagration mode of combustion process. The turbulence combustion flame cannot transit itself into detonation combustion process. So objective of this paper is to investigate the effect of obstacles configuration landed in detonation tube channel to propagate the detonation wave and diffraction encounters in an obstacles site. Four different cases of obstacles blockage ratio (BR) 0.4, 0.5, 0.6 and 0.7 were studied for detonation flame acceleration in detonation tube. A three dimensional computational simulation was done using unsteady green-gauss cell based solver for adopting the combustion simulation. As a result detonation flame propagation, detonation flame velocity and detonation flame pressure were increase in reducing blockage ratio from 0.7 to 0.4 and eddy viscosity of combustible mixture was increase with increasing the blockage ratio. From the analyzed four blockage ratio BR=0.4 is suitable for detonation mode of combustion and flame acceleration.

Detonation combustion wave is much more energetic combustion process in pulse detonation engine c... more Detonation combustion wave is much more energetic combustion process in pulse detonation engine combustion system. Numerous experimental, theoretical and numerical analyses have been studied in pulse detonation engine to implement in practical propulsion system. In this present computational study the simulation was carried out for deflagration flame acceleration and deflagration to detonation transition of hydrogen air combustible mixture inside the detonation tube with and without Shchelkin spiral. A three dimensional computational analysis has been done by finite volume discretization method using ANSYS Fluent 14 CFD commercial software. The LES turbulence model with second order upwind discretization scheme was adopted with standard boundary conditions for unsteady combustion wave simulations. From the computational study it was found that intensity of detonation wave velocity and dynamic pressure is higher near to the boundary of Shchelkin spiral in detonation tube. The contour plots comparisons clearly show that deflagration flame accelerates in detonation tube as present of Shchelkin spiral. The contour plots also suggest that deflagration flame velocity and pressure are less in without Shchelkin spiral in detonation tube. The accelerating detonation waves are approximately near about Chapment-Jouguet values in detonation tube with Shchelkin spiral.

T he helical Savonius rotor has a high starting torque and reasonable efficiency at low rotationa... more T he helical Savonius rotor has a high starting torque and reasonable efficiency at low rotational speeds during start-up and is able to provide a positive coefficient of static torque at all rotor angles. In order to improve the power and torque coefficients, a helical Savonius rotor at different twist angles -mainly 60°, 90° and 120° -is proposed. For this purpose, a helical Savonius rotor with a shaft of 40 cm in height and 24 cm in diameter and with 60°, 90° and 120° helix angles was designed in Gambit 2.3.16. In this paper, CFD analysis of the helical shape rotor using FLUENT 6.3 was used to predict performances such as power coefficient and torque coefficient at different tip speed ratios. Furthermore, two-bladed and three-bladed helical Savonius rotor performances were compared at 30°, 90° and 180° rotor angles and at 0.392, 0.523, 0.785, 1.57 and 2.09 tip speed ratios. A three-dimensional unstructured grid was developed to give the best meshing accuracy as well as computational results. An RNG k-ε turbulence model was used for pressure and velocity contour analysis with a standard wall function. It was con-cluded from the analysis that the highest power coefficient and torque coefficient values were obtained from a two-bladed 90° twist helical savonius rotor.

In this research work the flow behavior was analyzed, which affect the power coefficient as well ... more In this research work the flow behavior was analyzed, which affect the power coefficient as well as torque coefficient of a helical Savonius rotor is investigated by means of commercial code CFD. Conventional three bladed Savonius rotors have high coefficient of static torque at certain rotor angles and negative coefficient of static torque at certain rotor angle. In order to increase the efficiency of all rotor angles the system a helical Savonius rotor with a twist of certain proposed degree is introduced. A three-dimensional model of twist three blades helical Savonius rotor at , , and rotor angle has been constructed by using the software gambit of the Fluent 6.3 package. The contours of static pressure and velocity magnitude around the rotor blades area at horizontal iso-plane is obtained from the CFD simulation. High performance was obtained at advanced bucket in upstream air flow at rotor angle and maximum positive static pressure obtained at rotor angle, which affect the positive coefficient of static torque.

Books by Dr. PINKU DEBNATH

IntechOpen, 2022

Pulse detonation engines (PDEs) are most exciting for future propulsion generation. Detonation co... more Pulse detonation engines (PDEs) are most exciting for future propulsion generation. Detonation combustion in pulse detonation combustor is an energetic combustion process which is differs from other combustion process. The detonation wave propagation in detonation tube is a pulse setting combustion phenomena. Detonation combustion process is thousands times faster than deflagration combustion process. PDE utilizes several pulse of detonation wave to produce propulsive force. The potential applications of PDEs are drastically reduces the cost of orbit transfer vehicle system and flying mode applications. Of course it can be used as ground level applications also. Draw back are DDT in shortest possible time in the combustor. In this regards, worldwide researchers are focusing on scientific and technical issues related to improvement of PDC. The present chapter deals with review study on detonation combustion process, historical overview on chemical kinetics, calorimetric and entropy transport, energy and exergy analysis and factor effecting on deflagration to detonation transition with recommendable future research.

Springer Nature, 2020

The detonation combustion phenomenon is supersonic combustion process and follows on thermal expl... more The detonation combustion phenomenon is supersonic combustion process and follows on thermal explosion in combustor. Deflagration to detonation transition occurs in detonation tube due to pressure oscillation in PDE combustor, which is driven by acoustic combustion phenomena in detonation tube. As this combustion process has great significance role for future propulsion system, the present objective is to investigate the effect of modify ejector having half angles of α = (− 4°, 0°, + 4°) on detonation combustion wave propagation regime. Further the propulsion thrust of liquid kerosene and gaseous hydrogen–air mixture are also analyzed. This numerical simulation has been analyzed by LES turbulence model for DDT and shock wave pressure oscillation in pulse detonation combustor at Fluent based CFD plat form. The one-step irreversible chemical kinetics model analyzes the details exothermic chemical reaction mechanism inside the combustor. However, the shrouded ejector with taper angle of α = +4° performed the strong starting vortex generation and shortest possible time of 0.032 s for fully developed detonation wave. The simulation results also shows that thrust force augmentation of hydrogen–air mixture is greater compared to combustion process of liquid kerosene–air mixture with significant magnitude of 38 N. Although kerosene–air mixture produces less pollutant number but the propagation flame velocity is 2550 m s−1 for hydrogen/air mixture, which is near about C–J velocity and comparatively higher than kerosene/air combustion process.

Detonation combustion based engines are more efficient compared to conventional deflagration base... more 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.

Exergy losses during the combustion process, heat transfer, and fuel utilization play a vital rol... more Exergy losses during the combustion process, heat transfer, and fuel utilization play a vital role in the analysis of the exergetic efficiency of combustion process. Detonation is thermodynamically more efficient than deflagration mode of combustion. Detonation combustion technology inside the pulse detonation engine using hydrogen as a fuel is energetic propulsion system for next generation. In this study, the main objective of this work is to quantify the exergetic efficiency of hydrogen–air combustion for deflagration and detonation combustion process. Further detonation parameters are calculated using 0.25, 0.35, and 0.55 of H 2 mass concentrations in the combustion process. The simulations have been performed for converging the solution using commercial computational fluid dynamics package Ansys Fluent solver. The details of combustion physics in chemical reacting flows of hydrogen–air mixture in two control volumes were simulated using species transport model with eddy dissipation turbulence chemistry interaction. From these simulations it was observed that exergy loss in the deflagration combustion process is higher in comparison to the detonation combustion process. The major observation was that pilot fuel economy for the two combustion processes and augmentation of exergetic efficiencies are better in the detonation combustion process. The maximum exergetic efficiency of 55.12%, 53.19%, and 23.43% from deflagration combustion process and from detonation combustion process, 67.55%, 57.49%, and 24.89%, are obtained from aforesaid H 2 mass fraction. It was also found that for lesser fuel mass fraction higher exergetic efficiency was observed.

Pulse detonation engines (PDEs) are new exciting propulsion technologies for future propulsion ap... more Pulse detonation engines (PDEs) are new exciting propulsion technologies for future propulsion applications. The operating cycles of PDE consist of fuel-air mixture, combustion, blowdown, and purging. The combustion process in pulse detonation engine is the most important phenomenon as it produces reliable and repeatable detonation waves. The detonation wave initiation in detonation tube in practical system is a combination of multistage combustion phenomena. Detonation combustion causes rapid burning of fuel-air mixture, which is a thousand times faster than deflagration mode of combustion process. PDE utilizes repetitive detonation wave to produce propulsion thrust. In the present paper, detailed review of various experimental studies and computational analysis addressing the detonation mode of combustion in pulse detonation engines are discussed. The effect of different parameters on the improvement of propulsion performance of pulse detonation engine has been presented in detail in this research paper. It is observed that the design of detonation wave flow path in detonation tube, ejectors at exit section of detonation tube, and operating parameters such as Mach numbers are mainly responsible for improving the propulsion performance of PDE. In the present review work, further scope of research in this area has also been suggested.

Detonation is the supersonic mode of combustion process which is essential for energy release fro... more Detonation is the supersonic mode of combustion process which is essential for energy release from combustion process. Detonation is the more energetic process compare to deflagration mode of combustion process. The turbulence combustion flame cannot transit itself into detonation combustion process. So objective of this paper is to investigate the effect of obstacles configuration landed in detonation tube channel to propagate the detonation wave and diffraction encounters in an obstacles site. Four different cases of obstacles blockage ratio (BR) 0.4, 0.5, 0.6 and 0.7 were studied for detonation flame acceleration in detonation tube. A three dimensional computational simulation was done using unsteady green-gauss cell based solver for adopting the combustion simulation. As a result detonation flame propagation, detonation flame velocity and detonation flame pressure were increase in reducing blockage ratio from 0.7 to 0.4 and eddy viscosity of combustible mixture was increase with increasing the blockage ratio. From the analyzed four blockage ratio BR=0.4 is suitable for detonation mode of combustion and flame acceleration.

Detonation combustion wave is much more energetic combustion process in pulse detonation engine c... more Detonation combustion wave is much more energetic combustion process in pulse detonation engine combustion system. Numerous experimental, theoretical and numerical analyses have been studied in pulse detonation engine to implement in practical propulsion system. In this present computational study the simulation was carried out for deflagration flame acceleration and deflagration to detonation transition of hydrogen air combustible mixture inside the detonation tube with and without Shchelkin spiral. A three dimensional computational analysis has been done by finite volume discretization method using ANSYS Fluent 14 CFD commercial software. The LES turbulence model with second order upwind discretization scheme was adopted with standard boundary conditions for unsteady combustion wave simulations. From the computational study it was found that intensity of detonation wave velocity and dynamic pressure is higher near to the boundary of Shchelkin spiral in detonation tube. The contour plots comparisons clearly show that deflagration flame accelerates in detonation tube as present of Shchelkin spiral. The contour plots also suggest that deflagration flame velocity and pressure are less in without Shchelkin spiral in detonation tube. The accelerating detonation waves are approximately near about Chapment-Jouguet values in detonation tube with Shchelkin spiral.

T he helical Savonius rotor has a high starting torque and reasonable efficiency at low rotationa... more T he helical Savonius rotor has a high starting torque and reasonable efficiency at low rotational speeds during start-up and is able to provide a positive coefficient of static torque at all rotor angles. In order to improve the power and torque coefficients, a helical Savonius rotor at different twist angles -mainly 60°, 90° and 120° -is proposed. For this purpose, a helical Savonius rotor with a shaft of 40 cm in height and 24 cm in diameter and with 60°, 90° and 120° helix angles was designed in Gambit 2.3.16. In this paper, CFD analysis of the helical shape rotor using FLUENT 6.3 was used to predict performances such as power coefficient and torque coefficient at different tip speed ratios. Furthermore, two-bladed and three-bladed helical Savonius rotor performances were compared at 30°, 90° and 180° rotor angles and at 0.392, 0.523, 0.785, 1.57 and 2.09 tip speed ratios. A three-dimensional unstructured grid was developed to give the best meshing accuracy as well as computational results. An RNG k-ε turbulence model was used for pressure and velocity contour analysis with a standard wall function. It was con-cluded from the analysis that the highest power coefficient and torque coefficient values were obtained from a two-bladed 90° twist helical savonius rotor.

In this research work the flow behavior was analyzed, which affect the power coefficient as well ... more In this research work the flow behavior was analyzed, which affect the power coefficient as well as torque coefficient of a helical Savonius rotor is investigated by means of commercial code CFD. Conventional three bladed Savonius rotors have high coefficient of static torque at certain rotor angles and negative coefficient of static torque at certain rotor angle. In order to increase the efficiency of all rotor angles the system a helical Savonius rotor with a twist of certain proposed degree is introduced. A three-dimensional model of twist three blades helical Savonius rotor at , , and rotor angle has been constructed by using the software gambit of the Fluent 6.3 package. The contours of static pressure and velocity magnitude around the rotor blades area at horizontal iso-plane is obtained from the CFD simulation. High performance was obtained at advanced bucket in upstream air flow at rotor angle and maximum positive static pressure obtained at rotor angle, which affect the positive coefficient of static torque.

IntechOpen, 2022

Pulse detonation engines (PDEs) are most exciting for future propulsion generation. Detonation co... more Pulse detonation engines (PDEs) are most exciting for future propulsion generation. Detonation combustion in pulse detonation combustor is an energetic combustion process which is differs from other combustion process. The detonation wave propagation in detonation tube is a pulse setting combustion phenomena. Detonation combustion process is thousands times faster than deflagration combustion process. PDE utilizes several pulse of detonation wave to produce propulsive force. The potential applications of PDEs are drastically reduces the cost of orbit transfer vehicle system and flying mode applications. Of course it can be used as ground level applications also. Draw back are DDT in shortest possible time in the combustor. In this regards, worldwide researchers are focusing on scientific and technical issues related to improvement of PDC. The present chapter deals with review study on detonation combustion process, historical overview on chemical kinetics, calorimetric and entropy transport, energy and exergy analysis and factor effecting on deflagration to detonation transition with recommendable future research.