ПОРІВНЯЛЬНА ХАРАКТЕРИСТИКА МОРФОЛОГІЧНИХ ЗМІН СУДИННОГО РУСЛА НИРОК ПРИ ДЕЯКИХ ПАТОЛОГІЧНИХ СТАНАХ

У роботі висвітлено особливості гістологічної перебудови судинного русла нирок при гострому розлитому перитоніті та стенозі ниркової артерії, дано його комплексну морфологічну характеристику. Доведено характерну послідовність розвитку мікроскопічних змін у судинах нирок, що є наслідком безпосередніх гемодинамічних розладів, характерних для даних патологічних станів

Designing constraints in evaluation of ship propulsion power

Preliminary ship owners' assumptions for new ship consist of deadweight (for container vessel load capacity TEU), speed shipping line and others. Taking it as a base, in early stage of design one has to select propulsion type. This goal needs definition of principal dimensions of a vessel, which are the base for further calculations of hull’s resistance and evaluation of necessary power of main engine (engines) to fulfil shipping requirements. Selection of main dimensions of vessel is limited by rules regarding buoyancy, stability, hull strength, manoeuvring capability, and limitations related to seaways or harbours characteristic. In this paper is presented the methodology of calculation of principal parameters of a vessel, necessary for calculation of displacement in relation to vessel’s type, volumetric coefficients, Froude number, and others values affecting ship’s dimensions. It is about midship section coefficient, waterline coefficient, prismatic coefficients and hull feature and area coefficients. Those values are necessary for calculation of hull resistance. In the table are presented comparison of results of calculations above mentioned values and movement resistance and propulsion power of three container vessels representing different load capacity and one bulk carrier. There are also presented different calculation methods of transverse midship section coefficient and wet area coefficient, for 5000TEU container vessel

Dimensional constraints in ship design

The paper presents general rules for calculations of ship’s hull principle dimensions at preliminary stage of design process. There are characterized and defined basic assumptions of design process and limitations for calculations of dimensions and some criteria numbers. Limitations are an outcome of shipping routes what is related to shipping restrictions, diminishing of hull drag, achieving of required strength of hull and safety of shipping requirements. Shipping limitations are because of canals and straits dimensions or harbours drafts. In order to diminish propulsion power, what is related to economically justified solution, selected form and dimensions of hull must ensure minimizing of resistance, including skin friction and wavemaking resistance. That is why proper selection of coefficients of hull shape and dimensional criteria according to ship owner’s requirements i.e. deadweight (DWT) or cargo capacity (TEU), speed and seakeeping. In the paper are analyzed dimensional constraints due to shipping region, diminishing of wavemaking and skin friction resistance or application of Froude Number, ships dimensional coefficients (block coefficient, L/B, B/T, L/H) and coefficients expressing relations between capacity and displacement. The scope of applicability above presented values for different modern vessels construction were analyzed

Diagnosing of ship propulsion elements by vibration measurement

In the present time the technical progress, make us use more and more complicated machines in our everyday life. The application of turbine engines as the main propulsion engines of a vessel impels, according to requirements, operation procedures. It alters considerably the usage of gas turbine engines in the navy from the ones in aviation. The relatively low load is characteristic to the operation of the marine engine. In the case of the technology used at sea, the necessity of highly specialized service is especially evident. In the paper, we present the diagnostic systems elaborated to support the exploitation of the vessel power plant with gas turbines. Application of computer simulation for diagnosing a technical state of gas turbines rotor sets should be applied during calculation and project process. During engine assembly, the rotating components are mounted with great care with the main objective of minimizing shaft unbalance. However, even with the best of care, such factors as machining imperfection, differential thermal expansion etc cause a small residual unbalance of gas turbine rotor. The dynamic problems of Marine Gas Turbine Engines are connected with such basic elements: rotors, bearings, struts of bearings, engine body and type of substructure. The proposed diagnostics method makes it possible to determine the limiting value of vibration symptoms

System to evaluate the quality of studies in the marine propulsion plant engineering speclality at Gdynia Maritime University

Dla ujednolicenia jakości kształcenia na wszystkich kierunkach studiów i przez wszystkie Uczelnie, powołano Państwową Komisję Akredytacyjną (PKA). Opracowano kryteria które obejmują zagadnienia związane z zapewnieniem odpowiednich warunków studiowania pod względem bazy dydaktycznej, kadry nauczającej, programów nauczania (w tym spełnienie narzuconych minimum programowych), organizacji procesu dydaktycznego itp. Akademia Morska w Gdyni kształci i przygotowuje specjalistów do pracy na morzu. Stąd system dydaktyczny musi spełniać wymagania nie tylko PKA wymagania której są typowe jak dla Uczelni technicznej lecz i międzynarodowej konwencji STCW która narzuca odpowiednie wymogi odnośnie przedmiotów, liczby ich godzin, okresu i tematyki praktyk itp. Dla absolwentów którzy podejmą pracę na morzu problematykę spełnienia kryteriów kształcenia przedstawiono na przykładzie Wydziału Mechanicznego Akademii Morskiej w Gdyni, który kształci na kierunku Mechanika i Budowa Maszyn i przygotowuje absolwentów do pracy na morzu jako oficerów mechaników floty handlowej.In order to standardize the quality of education in all the courses and in all of the higher education institutions the State Accreditation Committee was founded in present form in 2002. There were prepared criteria that include the issues associated to assuring the adequate conditions of studying as far as the didactic base is concemed, teaching staff, didactic programrnes (included the fulfiIling the basic programme minimum), organization of the didactic process, etc. The Maritime University of Gdynia educates and trains the specialist for working at sea. Thus far, the didactic system must meet the requirements not only of the SAC (typical for a technical university) but also of the STCW convention that imposes adequate requirements as far as the subjects, number of hours, periods and subjects of practical training, etc. is concerned. For the graduates that will work at sea, the problems of meeting criteria of education was exposed taking as an example the Faculty of Marine Engineering of the Maritime University of Gdynia, which prepares students in the course of Mechanics and Machine Building and prepares graduates for the work at sea as mechanic officer of merchant marine

Resistance of idle propellers in marine multi-propeller propulsion systems

The configuration of a marine propulsion system is selected with regard to the maximum power resulting from its maximum design speed and displacement. The propulsion systems of high speed vessels use three or even four propellers, and each propulsion unit may be multi-engine. High speed vessels are designedfor maximum speeds, but their factual exploitation speed parameters are usually considerably lower - partial speed. In such cases particular propulsion propellers and engines need to be shut down. The idle propellers are dragged by the hull and they work in the so-called turbine work mode; they transfer torque to the shaft and generale negative thrust, i.e. additional resistance. Additional resistance contributes to reducing estimated speed of a vessel and increasing fuel consumption. What is more, torque generated on a propeller is transferred to the shaft and when friction resistance torque in shaft stuffing-boxes and bearings, transmission and, possibly, the propulsion engine is exceeded, mobile components rotate as a result, reaching considerable rotational speed values. torque and thrust on a propeller in this work mode may be estimated on the grounds of universal hydrodynamic characteristics of propellers. Universal hydrodynamic characteristics of propellers are used as reversion characteristics in evaluating the steering properties ofa vessel, and may be useful in evaluating resistance of free wheeling and locked propellers in marine multi-shaft propulsion systems. This paper presents charts of universal hydrodynamic characteristics of propellers for the full range of their rotational speed, the methodology and an example of calculating resistance of free wheeling and locked propellers for the given marine propulsion system

Resistance of idle propellers in marine multi-propeller propulsion systems

Jednostki szybkie projektowane są na maksymalne prędkości pływania, natomiast z reguły eksploatowane są prędkościami znacznie mniejszymi, tzw. częściowymi. Wymaga to wyłączenia z pracy poszczególnych silników czy śrub napędowych. Śruby niepracujące są holowane przez kadłub okrętu, pracują w zakresie tzw. pracy turbinowej i przekazują moment obrotowy na wał oraz wytwarzają ujemny napór, czyli powodują dodatkowy opór. Momenty i napory występujące na śrubie w tym zakresie pracy można oszacować w oparciu o uniwersalne charakterystyki hydrodynamiczne śrub. Zaprezentowano metodykę oraz przykład obliczania oporów śrub swobodnie obracających się i zastopowanych dla założonego układu napędowego okrętu.High speed vessels are designed for maximum speeds, but their factual operation speed parameters are usually considerably lower — partial speed. In such cases particular propulsion propellers and engines need to be shut down. The idle propellers are dragged by the hull and they work in the so-called turbine work mode; they transfer torque to the shaft and generate negative thrust, i.e. additional resistance. To estimate torque and thrust on a propeller in this work mode universal hydrodynamic characteristics of propellers may be used. This paper presents the methodology and an example of calculating resistance of freewheeling and locked propellers for a given marine propulsion system

Determination of main dimensions and estimation of propulsion power of a ship

TEU number, which is the container ships’ crucial designing factor, directly influences the main hull dimensions such as displacement V , length L, breadth B, draught T, their combinations and block coefficient CB. The main dimensions have a great impact on developing the ships resistant performance. Thus, it is really fundamental to establish the correct dimensions of the hull during the design and ship building process. Estimating the shape of the ship’s hull, that comprises its main dimensions, is one of the basic tasks as part of the preliminary design stage. The most significant decisions determining ships performance, its duration and building costs are made at the beginning of the preliminary stage, when the costs are relatively low. It is important to limit the total ship resistance, for instance, by lowering the wave ship resistance as much as possible, especially when the operational speed and TEU number carried by one vessel is increasing. That resistance depends on the operational speed expressed by Froude number. The resistance criteria and the existing hull dimensions limits, resulting from ships route, must be taken into consideration bearing in mind safety conditions such as ships stability and seaworthiness, when the main ships dimensions are being determined. In the paper are presented general rules for calculations of ship’s hull principle dimensions and total power of engines of container ship 1300TEU and 18 kn at preliminary stage of design process

Utilisation of data base in preliminary design of marine power plant

The paper presents general rules of utilization of database, called „significant ships list,” for preliminary design of ship’s propulsion and configuration of power plant. Knowledge collected in the database is related to new buildings classified according to type, displacement, shipping class etc. It encompass general dimensions, characteristics of mobility ,propulsion’s power and type of main engines and propulsors, electric power plant, boilers and main mechanisms of a power plant. In the paper is presented method of utilization of the significant ships list during design of a container ship with capacity of 1300 TEU and speed of 18 knots. The first step of propulsion and main engine’s selection is determination of main dimensions, i.e. displacement, length, draft and breadth. That dimensions cannot be selected random way, due to hull’s mobility, stability and durability constraints. The list of significant ships consisted of 30 units, and amongst them, 17 were selected and analyzed. Others were rejected because of significant difference from mean values what could be due to different class of the ships

Analiysis of propulsion for various types of ships in aspects of power required and fuel consumption during exploitation

The paper presents comparative analysis of energetic possibilities of different ships with close parameters of displacement and operational ailing range, for selected type of main engine. Analysis is related to three types of ships, i.e. bulk carrier, tanker and container ship, with assumed displacement at level of 120 000DWT and typical for that ships sailing speed. The analysis concerns shipping route from Gdynia to Shanghai. First step of conducted analysis was based on elaboration of the list of contemporary similar ships for every class, their general dimensions, dimensional coefficients, and subsequently evaluation of hulls resistances using Holtrop – Mennen Method necessary for calculation of propulsive power, main engines’ selection, most convenient for every type of ship and calculation of trips durations and fuel consumptions. All calculations were done assuming typical cruising speed for considered types of ships, it means 25 knots for container ships and 15 knots for tankers and bulkers. Results of carried out calculations lets come to the conclusion that total time of trip duration of container ship is 1.5 times shorter and fuel consumption is 2.5 times higher comparing with tankers and bulk carriers going on the same trip. Taking under consideration constantly growing prices of heavy oil, that situation is inconvenient from economical point of view. Above facts explains general trend to reduce speed of container ships presented by almost all shipping companies. The way of speed’s reduction is decreasing of continuous power rate of main engine, what is related to necessity of blinding or dismounting some numbers of turbochargers. Hypothetic example of such operation and its impact at operational properties were analysed, and results showed, that exploitation parameters of the container ship begun closer to bulk carriers and tankers but could not achieve proper level of efficacy due to not optimal hull shape and engine characteristic