Wyniki wyszukiwania - Biblioteka Nauki

Ten serwis zostanie wyłączony 2025-02-11.

Nowa wersja platformy, zawierająca wyłącznie zasoby pełnotekstowe, jest już dostępna.
Przejdź na https://bibliotekanauki.pl

Ograniczanie wyników

3 Journal of KONES

Znaleziono wyników: 3

Liczba wyników na stronie

Wyniki wyszukiwania

Sortuj według:

Ogranicz wyniki do:

Analysis and research of piston working conditions of combustion engine in high thermal load conditions

100%

Jankowska-Sieminska B. , Jankowski A. , Slezak M.

Journal of KONES

2007

tom Vol. 14, No. 3

233-243

Explanation of phenomena occurring in pistons of combustion engines which appear during heating and cooling processes in reference to standard materials and composite materials of high material proprieties is aim of the paper. Bring over researches were mostly directed on measurements of difference dimensions which appear during the piston work in the combustion engine. The paper concentrates on phenomenon of different proprieties of materials. The thermal stresses and shocks differ. In the thermal shock, thermal stresses are caused by instantaneous temperature gradients which appear at high engine speed. These stresses are determined thro temperature distribution and they do not differ from stresses in steady-state conditions. Researches concerning thermal expansions were performed by means of sensitive dilatometer which can work in simple and differential system. Changes of dimensions versus temperature function were measured with inductive sensor and the sensitive Pt-ptrh thermocouple, and results were referred to reference material-Platinum. Research results are illustrated on diagrams of different courses of changes of the of thermal expansion coefficient during heating and cooling of standard and composite materials. Values of the thermal expansion coefficient a for the heating and cooling are smaller for composite alloys. The course of the coefficient â during cooling can be higher or lower from the coefficient a during heating. Similar values were also received. Maximum differences were of 10%. Smaller values of the coefficient a for composite alloys cause that for such the same thermal loads temperature gradients will be smaller for composite alloys. Courses of changes of the coefficient â have a different characteristics suited from chemical composition of alloy, granularity of the composite component and thermal treatment.

Novel method appointing of the effective heat release coefficient during combustion process based on real indicator diagram

100%

Jankowski A. , Ambrozik A. , Jankowska-Sieminska B. , Ślęzak M.

Journal of KONES

2007

tom Vol. 14, No. 4

133-142

An object of the paper is a novel method of effective heat release coefficient appointing during combustion process of the based on the real indicator diagram. The process quality of the heat release during process of combustion is evaluated by value of the effective heat release coefficient. Accepted assumptions at appointing effective coefficient of heat release refer to acceptable that thermodynamical parameters of the working charge according to points of the real indicator diagram and the computational diagram are such the same, the maximum pressure of real working cycle of the engine is equal to the pressure of the computational cycle, work of the working charge performed in period from point of closing of the inlet valve to point of the beginning of the exhaust process are for both considered working cycles equal, heat values of the carried to the real and computational cycle are such the same. The method of appointing of the self-ignition delay period is presented in the paper, using to this end intersection point of two graphs of temperature course of the working charge prepared for the first phase of combustion process. Other methods appointing characteristics is suggested in paper basing on the real indicator diagram. The graphic illustration of the preparing method of characteristics of the relative quantity of the heat release during combustion process is illustrated in paper.

Composite alloy for IC engine pistons

100%

Jankowska-Sieminska B. , Jankowski A. , Sławinski Z.

tom Vol. 17, No. 2

159-166

Aluminum is the most popular matrix for the metal matrix composites The Al alloys are attractive due to their low density, their capability to be strengthened by precipitation, their good corrosion resistance, high thermal and electrical conductivity, and their high damping capacity. The characteristics of metal matrix composite materials are determined by their microstructure and internal interfaces, which are affected by their production and thermal mechanical treatment. Investigations to improve the combustion piston engines arę leading to improve the working process performance by increase ofits parameters, especially the average temperature of the thermodynamic cycle. New piston consists of two parts manufactured of standard and composite materials are presented in the paper. Composite alloy has chemical composition of short fibre with Al2 O3 was following, in the mass percentage: 96% Al2 03, 4%, SiO2. As the binder the colloidal silica was used in quantity 5%. The volume of fibres in the insert was 22 plus or minus 2% by volume. Bending strength of the insert was 0.5 MPa. Temperature and stresses distribution in standard piston and different versions of composite pistons are introduced in the paper. The paper presents the resistance of investigated materials on thermal shocks. Experimental veriflcation of manufactured composite pistons in the engine proved the larger exhaust temperaturę for about 20-70°C, in comparison with the engine with standard pistons (that gives the greater effectiveness of turbo charging application), proved the lowering of a individual volume of gases blow-bys to the crankcase, the lowering of noise level, larger resistance on thermal loads.