Vibration Diagnostics of Marine Diesel Engines Malfunctions Connected with Injection Pumps Supported by Modelling

The article presents main causes of malfunctions in marine diesel engines fuel injection systems. The measurement section focuses on damage to injection pumps. Measurements were carried out for three technical conditions of a given cylinder injection pump. At the same time, a simplified vibration model of the engine was presented allowing to indicate sensitive components in the frequency domain enabling identification of damages to injection pumps working with individual cylinders. Finally, the results obtained by modelling were compared with the results recorded during laboratory measurements

Preliminary Calculations for Minehunter\u27s Genset Foundations

The requirements for the foundations of naval vessel engines are based on classification rules devised by classification societies or/and military standardization rules. A class guideline was published, defining the requirements, acceptance criteria and machinery seating methods. There is also a schedule of basic calculation procedures for cast resin or rubber chocks which facilitates the process of machinery foundation design, preloading force calculation, the establishment of boundary conditions etc. In case of naval vessels, typical procedures do not meet tactical requirements due to potential explosion loads. Since minehunters are mainly deployed at sea, handling active, naval mines, the shock resistance calculation for the entire machinery, including the Genset, is required. The paper presents preliminary MatLab calculation methods which can be used to analyse the type, number and location of rubber or elastomer chocks. The procedure consists of input data such as UNDEX pressure and technical data of the Genset used in the Polish Navy. Calculation results include the analysis of the dynamic interaction between the Genset and the foundation, as well as the damping effect generated by the UNDEX (UNDerwater EXplosion) shock pulse

Analysis of the pressure wave parameters caused by TNT underwater explosion forced on the hull of minehunter

The paper presents the parameters of the pressure wave incident on minehunter hull structure modeled on the simplified vessel hull of Kormoran II project

Analysis of the pressure wave parameters caused by TNT underwater explosion forced on the hull of minehunter

The paper presents the parameters of the pressure wave incident on minehunter hull structure modeled on the simplified vessel hull of Kormoran II project. The pressure wave is caused by the sea mine explosion on wet board of the ship and propagates in the sea. To describe the pressure wave procedure pressure formulas which can be implemented on programs CAE based on the Finite Element Method (FEM) was used. The way of modeling short – term issues using FEM and constitutive equations describing the explosion of TNT in the sea was described. Naval mines used by the Polish Navy were characterized. Equivalents of selected explosives in relation to the TNT were posted. Geometry of mine destroyer was mapped as a shell – beam model. The results of the pressure wave incident on the hull as a function of charge weight and the location of the epicenter of the explosion was presented. Formulated conclusions and comments

Diagnostic Model of Fuel Installation of Marine Diesel Engine

The paper presents the results of simulation of marine diesel engine fuel injector malfunction and its effects on engine vibration. The work includes the analysis of the engine internal forces and their mathematical models. Simplifications are proposed to allow analyzing the system in one degree of freedom. The results of vibration simulations for the model with efficient fuel system and improperly adjusted injector are also presented. The comparison of simulation results with vibration measurements on the engine was also performed, the diagnostic model was identified and simulation errors were calculated. The complexity of other internal and external interactions is the subject of other studies by the authors. The paper analyzes only the effects of energy dissipation - vibration as a symptom of changes in the technical condition

Analysis of vibration time histories in the time domain for propulsion systems of selected engineering objects

This paper presents the results of research carried out on the basis of vibration analysis for propulsion systems of ships used on the same basin. Six propulsion systems, identical in terms of mechanics, placed on three seagoing vessels, have been analyzed. The considered files have been divided into catalogues, separately for each measurement point, each direction, each rotational speed, and separately for usable and unusable shaft lines. Thus, it was possible to obtain vibration time histories of particular shaft lines for every combination point/direction/rotational speed. The mean value and standard deviation have been calculated separately for usable and unusable shaft lines and for each combination and each calculated characteristic. Next, a characteristic of time histories were calculated in the time domain: integral, mean value, energy, mean power (rms squared), simple moment of I order, simple moment of II order, central moment of I order, central moment of II order, normalized simple moment of I order, normalized simple moment of II order, normalized central moment of I order, normalized central moment of II order, an abscissa of the signal square gravity center, variance of the signal square, the signal equivalent diameter. It has been established that the characteristic is of concentrated type for standard deviation lower than 15 % of the mean value. On this basis the abscissa of the signal square gravity center, variance of the signal square and the value of normalized correlation function have been determined. A module and the sum of standard deviations have been calculated from the difference of mean values for usable and unusable objects have been calculated for each combination and characteristic. Basing on this it has been determined whether a given characteristic is reliable, that is, whether the module from the difference in mean values is higher than the sum of standard deviations

Detection of Changes in the Opening Pressure of Marine Engine Injectors Using Vibration Methods

Injectors of marine engines are, apart from injection pumps, a key element of the fuel injection system. Their proper operation affects the quality and time of producing the fuel-air mixture in engine cylinders. The technical condition of the injectors also has an impact on engine performance and the emission of harmful compounds into the atmosphere. One of the basic injector damages occurring during their normal operation is the change of the injector opening pressure. The article presents mathematical relations indicating the occurrence of vibration diagnostic parameters that could potentially determine changes in the opening pressure of individual injectors. A two-stage passive-active experiment was carried out during which an injector working with different spring preload force was tested. The presented results of experimental tests confirm the possibility of determining whether the injector opening pressure is within the permissible range. The presented method does not require interference in the engine operation. measurements can be made during regular operation

Rotating systems misalignment identification using fuzzy clustering method

In the phase of operation, a technical system accomplishes goals which were the reason of the system designing and creation. The execution of operation tasks by the system causes changes in the system state. The changes in the dynamic state of rotating systems can be early identified by means of vibrations measurement. Therefore, the operational tests were performed in order to register time histories of vibrations. Next, characteristics of the collected vibration signals were recorded and the most significant of them were taken as an input for further studies. The studies were performed to formulate a method of identifying the rotating systems misalignment with high reliability. The method consists in fuzzy clustering implementation. According to the method the input signals were used to formulate the fuzzy clusters of the ability and inability states of the system. Thanks to the method, it is possible to identify the operation position of the system on base of the vibration signals analysis. In the paper the proposed method was described. The results of the method application for a gas turbine engine as an example of a rotating system are also presented. It should be emphasized that the reliability of the described operation state identification is higher than other methods implemented by the authors previously

Detection of Changes in the Opening Pressure of Marine Engine Injectors Using Vibration Methods

Injectors of marine engines are, apart from injection pumps, a key element of the fuel injection system. Their proper operation affects the quality and time of producing the fuel-air mixture in engine cylinders. The technical condition of the injectors also has an impact on engine performance and the emission of harmful compounds into the atmosphere. One of the basic injector damages occurring during their normal operation is the change of the injector opening pressure. The article presents mathematical relations indicating the occurrence of vibration diagnostic parameters that could potentially determine changes in the opening pressure of individual injectors. A two-stage passive-active experiment was carried out during which an injector working with different spring preload force was tested. The presented results of experimental tests confirm the possibility of determining whether the injector opening pressure is within the permissible range. The presented method does not require interference in the engine operation. measurements can be made during regular operation

Analysis of vibration time histories in the time domain for propulsion systems of minesweepers

This paper presents the results of research carried out on the basis of vibration analysis for propulsion systems of ships used on the same basin. Six propulsion systems, identical in terms of mechanics, placed on three seagoing vessels, have been analyzed. The considered files have been divided into catalogues, separately for each measurement point, each direction, each rotational speed, and separately for usable and unusable shaft lines. Thus, it was possible to obtain vibration time histories of particular shaft lines for every combination point/direction/rotational speed. The mean value and standard deviation have been calculated separately for usable and unusable shaft lines and for each combination and each calculated characteristic. Next, the characteristic of time histories was calculated in the time domain: integral, mean value, energy, mean power (rms squared), simple moment of I order, simple moment of II order, central moment of I order, central moment of II order, normalized simple moment of I order, normalized simple moment of II order, normalized central moment of I order, normalized central moment of II order, as well as the abscissa of the signal square gravity center, variance of the signal square, the signal equivalent diameter. It has been established that the characteristic for standard deviation lower than 15 % of the mean value is of concentrated type. On this basis the abscissa of the signal square gravity center, variance of the signal square and the value of normalized correlation function have been determined. A module and the sum of standard deviations have been calculated from the difference of mean values for usable and unusable objects for each combination and characteristic. Basing on this, it has been determined whether a given characteristic is reliable, that is, whether the module from the difference of mean values is higher than the sum of standard deviations