Józef Żurek

Experimental and numerical modelling of combustion process of liquid fuels under laminar conditions

The paper presents the results of experimental studies obtained in a special test stand, which was carried out with the addition of mass flow, summarizes the theoretical analysis of the phenomena occurring in the flow, and the calculations, which were performed using the modeling of flow in the channel. The two examples of model calculations for the two laminar Reynolds number values are shown. Paper presents: channel scheme for analyzing the flow arising as a result of adding mass, two-dimensional diagram of the computational domain with the mass addition, grid computing domain, two-component velocity field, the lines of current in the channel, the distribution of the vector field in the channel, the average velocity as a function of the distances, the speed and temperature distributions for each channel cross-sections for flow with various values of the Reynolds number. The increase in lateral velocity Vb , while maintaining constant lower speed Vd , decreases the thickness of the boundary layer, both the velocity and the thermal one, which was also referenced in experimental investigations, carried out on the special test rig, using LDV and PDPA laser techniques.

Modelling of combustion process of liquid fuels under turbulent conditions

Liquid fuel combustion model, taking into account washing out the fuel surface hot gas flow is presented. The laminar, transitional or turbulent flow exhaust gas stream takes place. This article refers to a turbulent flow. The model of the combustion process under turbulent flow conditions was used plane flow pattern. In the calculations of the turbulent flow was used two-dimensional turbulence model SST. This model is a version of another model – k-ω. The article presents the results of the velocity field (module with two velocity components), distribution of vector fields in a rectangular channel, flow lines, temperature distribution, velocity distributions and temperature, The article presents the results of the velocity field (module with two velocity components), distribution of vector fields in a rectangular channel, flow lines, temperature distribution, velocity distributions and temperature for different cross section, profile burnt samples loss of burned mass on the sample, velocity distributions for particular sections for of the profile mass loss speed, temperature distribution for particular sections for each speed profile loss in mass of for turbulent flow with a Reynolds number Re = 3,550. Developed theoretical combustion model has good reference for an experiment conducted in conditions of model confirmed using numerical and experimental studies of the boundary layer. The thickness of the laminar sublayer under turbulent flow conditions and laminar under laminar flow conditions have a significant impact on the course of the combustion process.

Engineering system reliability state identification methodology

Engineering System Reliability State Identification Methodology In the process of investigating physical aspects of failures there is a need for measuring various features of objects. For this purpose measuring system, which consists of: operator - measuring instrument was used. In the paper an attempt of determining affectivity of such system was done. Influence of the first and second type errors on affectivity of the measuring system was considered. It was also shown how to decrease these errors. Influence on the affectivity of the reliability measurement of the measuring instrument was analyzed. Graduate and immediate failures were considered. Then some final conclusions were formulated. Metodyka Identyfikacji Niezawodności Systemu Technicznego Przedmiotem artykułu jest metoda identyfikacji niezawodności systemu technicznego złożonego z operatora podejmującego decyzję na podstawie informacji pozyskiwanych przez przyrządy pomiarowe wybranych parametrów eksploatacyjnych. Proces decyzyjny może być podejmowany z użyciem błędnych informacji pierwszego i drugiego rodzaju. Dla potrzeb racjonalizacji procesu decyzyjnego w warunkach rzeczywistych opracowano przedmiotowy algorytm.

Some Problems of Identification of the State for the Purpose of Steering the Reliability of the Object

Systems are described with some specific features C{Ci, i=1, 2,...,n} (system parameters). These features usually include: reliability, safety, availability, repairability, life, survivability, etc. Requirements W{Wi, i=1, 2,...,n} are determined with reference to individual features. It is said that the system is in the state of ability, when a set of features is embodied in a set of requirements C⊂W. From the above statement it appears that the state of ability is the initial state for the system, i.e. C⊂W.

Method of Formulating the Required Number of Vehicles for Delivery Aircrafts in Aviation Fuel

Abstract An important part of the air base logistic system is the supply sub-system. In military operations the main delivery can be focused on munitions and aviation fuel. Effective management of the supply stream and the reliability of vehicles in the air base logistic system affect the quality of operations, which can be measured by on time provisions, economic factors and the reliability of vehicles. At present the number of tankers in the air base logistic system is based on experiences.

Analysis of the equipment operation system in terms of availability

Abstract In the article the process of operating a set of aircraft put into service at one time is examined. In order to maintain a balanced ratio ready to use and avoid the accumulation of hangars maintenance, analysed transient process operation determining the probability of objects reside in different operating states. An interesting issue is change of a readiness as dependence of the model of adopted qualification. The main result of this article is the value of the probability of being ready to use. The probability of reaching the limit value is assuming different depends on initial conditions and different models of the probability density distributions. The results indicate the need for further testing of models of probability distributions to determine the optimal method qualifications or technical object is in standby mode or not.

ANALYSIS OF THE MILITARY VEHICLES OPERATING PROCESS BY MEANS OF MARKOV PROCESSES

The article presents the method of analysing the operating process of Star military vehicles in their readiness aspect. The subject of research was the Military Economic Unit, recently created in the Polish Army. Markov processes were applied. A simple 5-state model was built, and the research was made in a discrete, as well as continuous time. The limit probabilities, both for the chain and the time, were estimated. Thanks to ChapmanKołomogorov-Smoluchowski equations, the long-term projections could be estimated. To ensure of operating processes, correctly object’s permissible transitions from the previous state to the next one were chosen. It was defined based on technical documentation and owned operational knowledge on the considered operating process. The mathematical description of a set of permissible transitions includes a matrix of permissible Si → Sj transitions from the previous state Si (lines) to the next one. The five-state system has possible and forbidden transitions are presented. Graph of permissible transitions for the five-state operation model usage, standby, maintenance, repair, standstill in repair; correlogram for the average duration of the state; evolution of the probability of the Star cars’ staying in the state of usage, standby, maintenance, repair, standstill in repair are presented in the article.

An application of characteristic function in order to predict reliability and lifetime of aeronautical hardware

The forecasting of reliability and life of aeronautical hardware requires recognition of many and various destructive processes that deteriorate the health/maintenance status thereof. The aging of technical components of aircraft as an armament system proves of outstanding significance to reliability and safety of the whole system. The aging process is usually induced by many and various factors, just to mention mechanical, biological, climatic, or chemical ones. The aging is an irreversible process and considerably affects (i.e. reduces) reliability and lifetime of aeronautical equipment. Application of the characteristic function of the aging process is suggested to predict reliability and lifetime of aeronautical hardware. An increment in values of diagnostic parameters is introduced to formulate then, using the characteristic function and after some rearrangements, the partial differential equation. An analytical dependence for the characteristic function of the aging process is a solution to this equ...

Non-intrusive Diagnostic of Middle Bearing of Aircraft Engine

Failure of the middle bearing in an aircraft rotor engine was reported. Tip-timing and tip-clearance analyses were carried out on a compressor rotor blade in the seventh stage above the middle bearing. The experimental analyses concerned both an aircraft engine with a middle bearing in good working order and an engine with a damaged middle bearing. A numerical analysis of the free vibration of the seventh stage blade was conducted to explain the experimental ones. Proposed in this paper is a method to prevent middle bearing failure.

Selected Aircraft Throttle Controller With Support Of Fuzzy Expert Inference System

Abstract The paper describes Zlin 143Lsi aircraft engine work parameters control support method – hourly fuel flow as a main factor under consideration. The method concerns project of aircraft throttle control support system with use of fuzzy logic (fuzzy inference). The primary purpose of the system is aircraft performance optimization, reducing flight cost at the same time and support proper aircraft engine maintenance. Matlab Software and Fuzzy Logic Toolbox were used in the project. Work of the system is presented with use of twenty test samples, five of them are presented graphically. In addition, system control surface, included in the paper, supports system all work range analysis.