Wyniki wyszukiwania - BazTech

1

Resistojet thruster with a power system based on supercapacitors

Mezyk L., Kobiera A., Boruc L., Biczel P., Wolanski P.

Challenges of Modern Technology

|

2014

|

Vol. 5, no. 3

13--21

EN

This paper presents research into a resistojet model that can be powered by supercapacitors for satellite propulsion applications. The performance of the system, calculated including a preliminary study of mass and power budget, shows that this solution has potential for a certain range of space missions. The main problem when designing a pulsed resistojet is the compromise between the thermal capacity of the resistojet and the heat transfer efficiency of the device. When the heater is used in pulsed mode, it should have low mass and thermal capacity in order to reduce the energy required to heat the devices. On the other hand, the main technical restriction in resistojet thrusters is heat transfer due to the laminar regime of the flow in the heater. The heat transfer area should be as large as possible, but the mass of the device limits any such increase in area. In this research several design options were considered in an attempt to find the optimal solution. After research on the oscillating element and porous heater, capillary tubes directly heated by the current were determined to be the most effective solution. A power supply based on supercapacitors was constructed. It consists of 30 supercapacitors of 300 F each, connected to deliver 70 V of voltage, 10F of total capacitance and maximum peak power of 5 kW. Research for three different gases – ammonia, propane and butane – was conducted and the results are presented in this paper.

2

Three - dimensional numerical simulations of the combustion chamber of the rotating detonation engine

Folusiak M., Swiderski K., Kobiera A., Lukasik B., Wolanski P.

Journal of KONES

|

2013

|

Vol. 20, No. 1

83--88

EN

From 2010 Warsaw University of Technology (WUT) and Institute of Aviation (IoA) jointly implement the project under the Innovative Economy Operational Programme entitled ‘Turbine engine with detonation combustion chamber’. The goal of the project is to replace the combustion chamber of turboshaft engine GTD-350 with an annular detonation chamber. During the project, the numerical group that aims to develop computer code allowing researchers to simulate investigated processes has been established. Simulations provide wide range of parameters that are hardly available from experimental results and enable better understanding of investigated processes. Simulations may be also considered as a cheap alternative for experiments, especially when testing geometrical optimizations. In this paper the analysis of simulation results of the combustion chamber of the Rotating Detonation Engine (RDE) investigated at the IoA in Warsaw is presented. Primarily, REFLOPS USG which has become a fundamental numerical tool in the research of the RDE at the IoA is briefly described and governing equations and numerical methods used are shortly presented. Some aspects of numerical simulations of the RDE, related to selection of combustion mechanism, and an initiation of rotating detonation are provided. Secondly, results of simulations of inviscid gas with numerical injectors of hydrogen are compared with available experimental results. Three different wave patterns are identified in numerical solution and briefly described. Results of simulations are compared to experimental results in combustion chamber. Results presented in this paper are part of the project UDA-POIG.01.03.01-14-071 ‘Turbine engine with detonation combustion chamber’ supported by EU and Ministry of Regional Development, Poland.

3

Numerical tools for three dimensional simulations of the rotating detonation engine in complex geometries

Swiderski K., Folusiak M., Kobiera A., Lukasik B., Wolanski P.

Journal of KONES

|

2013

|

Vol. 20, No. 1

329--336

EN

This paper describes the development of a computational code REFLOPS USG (REactive FLOw solver for Propulsion Systems on UnStructured Grids) based on the Favre averaged Navier-Stokes equations with chemical reactions for semi-ideal multicomponent gas to predict the structure and dynamics of three-dimensional unsteady detonation as it occurs in the Rotating Detonation Engine (RDE). This work provides an overview of second order accurate in time and space finite volume method applied to conservation equations and its implementation on unstructured self-adaptive tetrahedral or hexahedral three-dimensional cell-centred meshes. The inviscid fluxes are given by the Riemann solver and stabilization is ensured by the proper limiters inherited from the TVD theory or gradient based limiters. The stiff equations of chemical kinetics are solved by use of implicit DVODE (Double precision Variablecoefficient Ordinary Differential Equation solver, with fixed-leading-coefficient implementation) routine or by explicit Chemeq2 routine. Additional improvements are incorporated into the code such as parallelization in OpenMP and implementation of NVIDIA CUDA technology. REFLOPS USG has become a fundamental numerical tool in the research of RDE at the Institute of Aviation in Warsaw, in frame of Innovative Economy project UDA-POIG.01.03.01-14-071 ‘Turbine engine with detonation combustion chamber’ supported by EU and Ministry of Regional Development, Poland. The simulations presented in this paper are based on inviscid or viscous multicomponent semi-ideal gas flow with chemical reactions. Due to high computational costs only simple chemical reaction mechanisms are used here.

4

Monitoring of combustion processes in industrial burners using electrical capacitance tomography

Gut Z., Wolanski P., Oleszczak P.

Journal of KONES

|

2011

|

Vol. 18, No. 3

117-121

EN

The development of diagnostic methods suitable for the monitoring of practical flames is an important objective, which is receiving a growing attention and significant research efforts. This is motivated by the need to achieve a more precise description of the process and, ultimately, implement efficient and reliable control and optimization methods as a key step towards the development of more efficient, flexible, reliable and clean combustion systems. Many interesting attempts have been proposed, involving very different approaches in the use of various instruments and sensors. One of parameter difficult to control is distribution of reaction zone. Presently, such system which allows monitoring combustion process of industrial burners does not exist. Measurements of temperature or control of exist flame by using ionization probe provide only partial information about performance of combustion process. For that reason, new diagnostic methods should be developed. Many and interesting attempts have been proposed but one of interesting solution will be development of combustion process diagnostic methods by means of the Electrical Capacitance Tomography (ECT). Obtained results show that it will be a very good tool for research proposes, especially in development of a new combustion chamber operated at very high pressure, where installation of optical windows is very difficult and many time not possible.

5

Numerical modelling of coal mine explosion

Klemens R., Kosinski P., Wolanski P., Korobeinikov V. P., Markov V. V., Menshov I. S., Semenov I. V.

Archivum Combustionis

|

2001

|

Vol. 21 nr 1

71-79

EN

The investigation of unsteady processes behind shock waves propagating in a gasdust combustible mixture is very important to understand mechanisms of industrial dust explosions like those in coal mines. In the paper, two aspects of this study are considered. The first one concerns questions related to ignition and burning of the mixture, where some results are given of numerical investigation of the transition to detonation process. Also 2D structure of unsteady detonation in the mixture of coal particles with air is taken into consideration. In the applied model, the moving medium is treated as a two-phase, two-velocity and two-temperature continuuum with mechanical and thermal interaction between the phases. Devolatilization, gas-gas and gas-particle exothermic chemical reactions, radiation and heat conduction are also taken into account. The other aspect is the problem of the dust enhancement and dispersion from the dust layer behind a shock wave. The forces caused by particles rotation and gas vorticity are taken additionally into account. Two numerical methods were developed to solve numerically the considered problems. Examples of calculations are presented.

6

Radiant ignition of wood untreated and treated with fire retardant

Glinka W., Helwig M., Wolanski P.

Archivum Combustionis

|

2000

|

Vol. 20 nr 1-2

33-39

EN

The influence of fire retardant on ignition of wooden materials by radiation of a relatively high intensity was experimentally investigated. The ignition process was visualized by using Schlieren method and recorded by a camera. The study was focused on the relation between ignition delay time and radiation intensity for treated and untreated materials. Pictures showing differences in development of ignition processes for different samples were used to evaluate ignition delay and mechanism of ignition process. Results show that ignition process proceeds in a different way for treated and untreated materials. It was proved that tested fire retardant acts as an absorbent of radiative energy by melting in the first stage and then by generating non-flammable gases.