Wide and multiple apex seals for the rotary engine (Abbr.: Multi-Apex-Seals for the Rotary Engine)
Conventional rotary engines are based on a trochoidal-type housing bore profile and its inside envelope is the basis of the rotor profile. To seal the chambers, spring-loaded apex seals are used in place of the designed rotor apexes. The conventional design method is limited to an epitrochoidal-based housing and does not consider the apex seal profile. Previously the authors presented the complete theory and algorithm of the deviation-function (DF) method of rotary engine design based on the apex seal profile. By using the DF method, the apex seal and engine housing bore are conjugate kinematic pairs, which enable the design of a variety of apex seals that conform to the bore, including wider apex seals and multiple seals at each rotor apex. The wide apex seal design has better rotor-to-housing conformity and therefore improves sealing. The multi-apex-seal grid assembly improves sealing capability and also reduces the forces on the apex seals. The incorporation of apex seal profiles into the rotary engine design process also makes possible a larger variety of new rotary engine profiles.
- [Show abstract] [Hide abstract] ABSTRACT: The side-ported rotary engine is a potential alternative to the reciprocating engine because of its favorable performance at low speed. The performance of side-ported rotary engines is strongly influenced by the flow field in the combustion chamber. In this study, an optical side-ported rotary engine test-bed was built and PIV was employed to measure the flow field in the rotor housing central plane. From experiment results, a counterclockwise swirl was detected in the rotor housing central plane. Meanwhile, a three-dimensional dynamic mesh and turbulent flow model was integrated and simulated using the Fluent CFD software. The three-dimensional dynamic simulation model was validated by comparison with experimental results. In addition, the effect of three major parameters on the flow field in the combustion chamber, namely rotating speed, intake pressure and intake angle were numerically investigated. The results show that a swirl forms in the middle and front of the combustion chamber during the intake stroke under low rotating speed. This is in line with the swirl detected in the rotor housing central plane though the PIV experiment at 600 rpm. Furthermore, the flow field, volume coefficient and average turbulence kinetic energy in the combustion chamber were studied in detail by varying rotating speed, intake pressure and intake angle.0Comments 2Citations
- [Show abstract] [Hide abstract] ABSTRACT: This work aims to numerically study the performance, combustion and emission characteristics of a side-ported natural-gas-fueled rotary engine under different pocket shapes and ignition slot positions. Simulations were performed using multi-dimensional software FLUENT 14.0. On the basis of the software, a three-dimensional dynamic simulation model was established by writing dynamic mesh programs and choosing a detailed reaction mechanism. The three-dimensional dynamic simulation model, based on the chemical reaction kinetics, was also validated by the experimental data. Simulation results showed that a bigger intensity of the tumble, a larger area of the high speed oblique flow and a higher average flow speed in the middle of the combustion chamber can make the flame propagation speed increase. When the combustion chamber configuration had a middling pocket coupled with an ignition slot located at the middle of the width direction of rotor surface, the combustion rate is the highest. As a result, the cylinder pressure and the intermediate OH increased significantly. Compared with the combustion chamber configuration, which had a flat-top pocket without ignition slot, it showed a 10 percent increase in the peak pressures, but a certain increase in NO emissions.0Comments 2Citations
- [Show abstract] [Hide abstract] ABSTRACT: The side-ported rotary engine fueled with natural gas is a new, clean, efficient energy system. This work aims to numerically study the performance, combustion and emission characteristics of a side-ported rotary engine fueled with natural gas under different ignition positions and ignition timings. Simulations were performed using multi-dimensional software ANASYS Fluent. On the basis of the software, a three-dimensional dynamic simulation model was established by writing dynamic mesh programs and choosing a detailed reaction mechanism. The three-dimensional dynamic simulation model, based on the chemical reaction kinetics, was also validated by the experimental data. Meanwhile, further simulations were then conducted to investigate how to impact the combustion process by the coupling function between ignition operating parameter and the flow field inside the cylinder. Simulation results showed that in order to improve the combustion efficiency, the trailing spark plug should be located at the rear of the tumble zone and the ignition timing should be advanced properly. This was mainly caused by the trailing spark plug being located at the rear of the tumble zone, as it not only allowed the fuel in the rear of combustion chamber to be burnt without delay, but also permitted the acceleration of the flame propagation by the tumble. Meanwhile, with advanced ignition timing, the time between ignition timing and the timing of the tumble disappearance increased, which led to an increase of the tumble effect time used to improve the combustion rate. However, the drawback of this improved combustion was the slight increase in NO emissions. Under the computational condition, when the trailing spark plug scheme of case C coupled with an ignition timing of 50 °CA (BTDC) was compared with the spark plug location and the ignition timing of the original engine, it showed a 27.4% increase in the peak pressure. Taking the limited increase of NO exhaust into consideration it was the best ignition allocation scheme under the computational condition. This study provided a theoretical foundation for the determination of best ignition position and ignition timing under different working conditions.0Comments 1Citation