Actual Engine Test Research Articles

실시간 가스터빈 엔진 시뮬레이터를 적용한 소형 제트엔진 성능시험장치 개발

가상엔진 시뮬레이터를 이용한 시험장치는 실제 엔진을 이용한 시험과 유사한 시험 수행을 통하여 엔진 시험 횟수를 줄이고 동일한 조건에서 반복 시험이 가능하므로 엔진 정비 및 운용비용을 감소시켜 준다. 그리고 실제 시험에서 수행하기 어려운 극한 상황을 쉽게 구현할 수 있기 때문에 실제 엔진 시험 시 발생할 수 있는 엔진 손상 및 위험한 시험을 대체해 준다. 본 연구에서는 사전 연구를 통해 개발하였던 소형제트엔진 성능시험장치에 실시간 엔진 모델을 적용하여 실제 엔진 시험과 가상 엔진 시험을 다목적으로 수행할 수 있는 업그레이드 된 소형제트엔진 성능시험장치를 개발하였다. 새로 개발된 다목적 소형 제트엔진 성능시험장치는 교육용 및 연구용으로 더욱 다양하게 활용될 수 있을 것으로 기대된다. Test device using virtual engine simulator can help reduce the number of engine tests through tests similar to the actual engine tests and repeat the test under the same condition, and thus reduce the engine maintenance and operating costs. Also, as it is possible to easily implement extreme conditions in which it is hard to conduct actual tests, it can prevent engine damages that may happen during the actual engine test under such conditions. In this study, an upgraded small jet engine performance test device was developed that can conduct both real and virtual engine test by applying real-time engine model to the existing micro jet engine performance test device that was previously developed by authors. This newly developed multi-purpose small jet engine performance test device is expected to be used for various educational and research purposes.

Research on Cylinder Head Thermal State Simulation

The thermal state of the cylinder head has a huge influence on its fatigue and damage situation; therefore it is essential to accurately simulate the thermal state of the cylinder head during engine operation. In this paper, a method research of the cylinder head thermal state simulation test has been done. A thermal state simulation test bench has been launched, using induction heating and water-cooling to regulate the temperature. A series of cylinder head surface temperature field simulation tests has been accomplished. Compared to the actual engine test results, the temperature simulation results have an average error of less than 5% and a maximum error of 8.5% in these temperature test points. It turns out that the test bench can simulate the actual cylinder head temperature distribution accurately and will has significant effects on the research of the cylinder head thermal stress distribution and thermal fatigue situation.

The Effect of Cylinder Bore Distortion on Lube Oil Consumption and Blow-By

It is well known that cylinder bore deformations during engine operation cause a number of problems in piston ring lubrication. Particularly, the deterioration of piston ring and cylinder bore conformability results in a significant increase in lubricating oil consumption. Therefore, measurement and identification of cylinder bore distortion has been an important subject for engine designers. In this study, an analytical lubricating oil consumption model was developed for a diesel engine. Piston stiffness was identified as an important input parameter for the oil consumption model, and the stiffness matrix of the piston was calculated using finite element simulations. In addition, finite element analysis was performed to determine the distorted cylinder block shape in engine running conditions. Pressure curves and loads obtained in actual engine tests were used in the analysis. The Fourier coefficients of a distorted cylinder bore was calculated which characterize the deformed bore orders. Using these Fourier coefficients, several distorted bore shapes were regenerated, including a straight bore and the effect of each order on total lube oil consumption was investigated by means of the oil consumption model.

Static Loading Test of the End-Bearing Pile under the Sides Friction Action

Because the pile foundation has the characters of high bearing capacity, small deformation and easy to construct, it is widely used in practical engineering. In order to verify the end-bearing pile loading capability, in this paper, the single pile vertical compressive static load test is used to the on-site measuring point in actual engineering test, and get the Q-S curve of the pile. FEM is used to simulate the test at the same time. The ideal elastic-plastic constitutive model based on Mohr-Coulomb failure criteria is used to simulate foundation soil. Some conclusions are obtained by using large scaled finite element analysis software ADINA to build the 2D plane strain finite element model and to proceed numerical analysis of the pile. Finally, the comparative analysis with the engineering practice is proceeded. It has the practical significance for the structure analysis of the single pile.

Design and optimization of an Atkinson cycle engine with the Artificial Neural Network Method

The Atkinson cycle engines have larger expansion ratio, thus higher thermal efficiency, which are more suitable for the hybrid fuel-electric vehicles than the conventional Otto cycle engines. Larger expansion ratio in an Atkinson cycle engine can be realized by increasing the geometrical compression ratio. Late Intake Valve Closure (LIVC) strategy is adopted to reduce the effective compression ratio to avoid the knock. However, the LIVC operation would reduce the effective displacement of the engine hence decrease the power density. There is a tradeoff between the thermal efficiency and Widely Open Throttling (WOT) torque/power. Computation-efficient nonlinear models for the baseline engine were built based on the Artificial Neural Network (ANN) technique. The ANN models were trained and tested using the data computed by a precisely calibrated GT-Power engine simulation model. Interactive effects of the LIVC, geometrical compression ratio, spark timing and air-to-fuel ratio on the fuel economy, WOT torque, knock intensity and exhaust temperature were deeply investigated. Optimization of the geometrical compression ratio and operating parameters was conducted based on the optimum ANN models. The optimization objective is to maximize the fuel economy, under the restriction conditions of WOT torque reduction percentage, knock intensity, and exhaust temperature. The optimum geometrical compression ratio was finally determined as 12.5. Experimental results obtained from the actual engine tests have validated the excellent prediction accuracy of the ANN models. Significant fuel economy improvement, of 6–13% at most WOT operating conditions, is obtained for the Atkinson cycle engine with acceptable compromise in the WOT torque.

Research and Development of Double Swirl Combustion System for a DI Diesel Engine

In order to make full use of the air in the chamber, improve the mixing process, and reduce raw emissions and fuel consumption of diesel engine, we introduce the the concept of a new combustion system—the Double Swirl Combustion System (DSCS)—and introduce their hypothesis regarding the fuel-air mixing mechanism under DSCS. For validating the hypothesis, we made a series of actual diesel engine tests on DSCS. The engine tests were based on a 150-mm diesel engine, and both single-cylinder and multicylinder engines were tested under natural aspirated intake condition and boost intake condition. The results indicate that DSCS is suitable for improving a big bore diesel engine. Later, we made a series of spray experimental researches in order to investigate DSCS and whether it can be used under different load conditions. In addition, we investigated how the structural parameters of the DS chamber affect the fuel-air mixing process in order to establish an optimum design method of the DS chamber. In order to verify whether DSCS can be used in different types of diesel engines, we made a series of engine tests on a 132-mm diesel engine. Results indicated that DSCS also can present a wonderful performance on medium bore diesel engine. For phenomena of 150- and 132-mm diesel engines' performance by matched DSCS, we suppose there exists necessary to make a further research on DSCS from the microcosmic level. Therefore, we made a series of simulations on 132-mm DS and the 132-mm original chambers. From the simulation results, they obtained meaningful results from the velocity field and temperature distribution comparisons. The results we obtained validate that DSCS has many advantages, such as a diesel engine with an ideal heat release rate, a better fuel economy, a lower emission, and a lower thermal load, all showing potential and a bright future for DSCS owing to the wide application of electronic-controlled fuel injection systems.

Design and Implementation of a Digital Multimode H∞ Controller for the Spey Turbofan Engine

In this paper, a 2 degrees-of-freedom multimode controller design for the Rolls Royce Spey turbofan engine is presented. The controller is designed via discrete time H∞-optimization; it provides robust stability against coprime factor uncertainty, and a degree of robust performance in the sense of making the closed-loop system match a prespecified reference model. Multimode control logic is developed to preserve structural integrity of the engine by limiting engine variables to specified safe values. A simple strategy for antiwindup and bumpless transfer between controllers, based on the Hanus anti-windup scheme (1987, “Conditioning Technique, A General Anti-Windup and Bumpless Transfer Method,” Automatica, 23(6), pp. 729–739) and the observer-based structure of the controller, is presented. The structure of the overall switched controller is described. Actual engine test results using the Spey engine test facility at Pyestock are presented. The controller is shown to perform a variety of tasks, its multimode operation is illustrated and improvements offered on existing engine control systems are discussed.

CT2-1: Application of a Reduced Elementary Reaction Scheme to Three-dimensional Numerical Simulation of Knocking Phenomenon in a Spark Ignition Engine Fueled by LPG-DME Mixture(CT: Combustion, Thermal and Fluid Science,General Session Papers)

In this study, the authors tried to understand the knocking phenomenon in a spark ignition engine fueled by LPG-DME mixture. The authors' original 3-D CFD code "GTT" linked to the CHEMKIN-II subroutines, called "GTT-CHEM", was used for not only understanding this knocking phenomenon but also estimating the knock intensity, which is usually measured by the completely different way on the test bed, from the CFD results. Then, a several different shapes of piston cavity were examined by both CFD and actual engine tests. As to the 3-D chemical kinetics calculation technique, for largely saving the computational time with little deterioration of accuracy, the authors constructed a reduced elementary reaction scheme for LPG-DME mixture by combining and reducing the GRI-Mech's scheme for LPG (mostly propane) and the Curran's scheme for DME. This reaction scheme was employed in the GTT-CHEM code, into which a modified version of the Kong's turbulent combustion model based on elementary reactions was incorporated. The GTT-CHEM code with the original reduced elementary reaction scheme was able to reproduce the knocking phenomenon reasonably well in the LPG-DME mixture fueled spark ignition engine. Finally, after actual engine experiments about different piston cavities, it has been found that a knocking intensity estimation index derived from HCHO behavior in CFD results is a good prophetic index to expand the knocking limit.

Multi-input Multi-output System Identification Using Impulse Responses

This paper presents a new algorithm for a multi-input multi-output (MIMO) system identification in the time domain using impulse responses. Eigensystem Realization Algorithm (ERA) realizes a single-input multi-output (SIMO) system using single impulse input, therefore we modify the method for identifying the system matrix of MIMO system. Moreover, a recursive least-square iteration scheme is developed to refine input and output matrices of the system. In this manner, the input matrix is considered to be constructed by the mode shapes and actuator sensitivity matrix. Numerical simulation for an actual spacecraft-the Engineering Test Satellite-VI (ETS-VI) is performed to verify the new algorithm. In the example, the nominal dynamics model of ETS-VI, which has six rigid body modes and fourteen elastic modes derived from large flexible solar panels, is excited by six body-mounted thrusters each, and three translational velocities and three attitude rates are assumed to be measured simultaneously. The proposed method identifies all of fourteen natural frequencies, damping ratios and mode shapes. The results of the numerical example show the validity of the new identification scheme.

Development and Evaluation of Ceramic Components for a Gas Turbine

An 8000 kW class Hybrid Gas Turbine (HGT) project, administered by the New Energy and Industrial Technology Development Organization (NEDO), was completed in March 2004. The targets of this project were improvement in thermal efficiency and output power by using ceramic components, and early commercialization of the gas turbine system. The ceramic components were used for stationary parts subjected to high temperature. It became clear that silicon nitride material showed significant recession under combustion gas. Kyocera and Central Research Institute of Electric Power Industry developed new EBCs to suppress this recession. These EBCs were evaluated by exposure test, heat cycle test and actual HGT engine test. One of the EBCs showed slight defects after the actual engine tests. However, all EBCs showed high corrosion resistance and good adhesion. It was confirmed that the all EBCs worked effectively.

Development of Silicon Nitride Components for Gas Turbine

Silicon nitride is one of the most practical candidates for ceramic gas turbines. The SN282 is silicon nitride material developed by Kyocera for gas turbines. Several new technologies have been developed to achieve materialization of ceramic gas turbines, such as material, fabrication process, evaluation / analysis technology. Recent technology is focused on recession of silicon-based ceramics under combustion gas. Environmental Barrier Coatings (EBCs) are developed to suppress these recession. We have found rare-earth element silicate and yttrium stabilized zirconium oxide (YSZ) have high corrosion resistance to the combustion gas. These materials were applied to the ceramic gas turbine components. The components with EBCs were evaluated in the actual engine tests. We have confirmed that the EBCs effectively work for the recession resistance.

Local Development of a Production Process for Replacement Cylinder Head

Several constraints exist in the local market as regards the purchase and after - sales services of small stationary diesel engines used for flour milling, water pumping and generation of electricity. These constraints could be substantially addressed through local production of frequently used spares. This paper describes the local development of a production process for a cylinder head of a single cylinder diesel engine. The design drawings were used to design the pattern and core box, to mould and make the core assembly which were subsequently dried in an oven before pouring of molten metal. The cylinder head manufactured by the process was pressure tested for integrity of the water jackets and ports before machining and actual engine tests. The performance of the cylinder head during the on load and no load tests were considered normal. Journal of Agriculture, Science and Technology Vol.3(2) 2001: 84-95

Fuzzy Logic Estimation Applied to Newton Methods for Gas Turbines

Abstract This method, based on fuzzy logic principles, is intended to find the most likely solution of an over-determined system, in specific conditions. The method addresses typical problems encountered in gas turbine performance analysis and, more specifically, to the alignment of a synthesis model with measured data. Generally speaking, the relatively low accuracy of measurements introduces a random noise around the true value of a performance parameter and distorts any deterministic solution of a square matrix-based linear system. The fuzzy logic estimator is able to get very close to the real solution by using additional (pseudo-redundant) parameters and by building the most likely solution based on each of the measurement accuracies. The accuracy—or “quality”—of a measurement is encapsulated within an extra dimension which is defined as fuzzy and which encompasses the whole range of values, between 0 (false) and 1 (true). The value of the method is shown in two examples. The first simulates compressor fouling, the other deals with actual engine test data following a hardware modification. Both examples experience noisy measurements. The method is stable and effective even at high level of noise. The results are within the close vicinity of the expected levels (within 0.2% accuracy) and the accuracy is about ten times lower than the noise level.

Research on the Fundamental Property of Flanged Spark Plug and Application to Natural Gas Engine

Spark ignition characteristics of flanged spark plugs have been studied experimentally. Experiments were performed using a constant volume combustion chamber and a natural gas engine. Flanged spark plugs were made by remolding spark plugs on the market. The minimum ignition energy was employed to evaluate the ignition characteristics of the flanged spark plugs. It was found that the flanged spark plug reduces the minimum ignition energy. It was observed by schlieren photography that the shock wave was reflected by the flanges concentrated on a flame kernel. This fact suggests that the adiabatic compression due to the shock concentration reduces the minimum ignition energy. There is little effect of the flange on the flame speed, although it is well known that the existence of flanges prevents the initial growth of the flame kernel. It was found that, in actual engine test, the ignition probability is increased and the lean limit is extended.

Forced response analysis of a shaft-driven lift fan

The aim of this paper is to give an overview of the multi-bladerow forced response analyses carried out on a shaft-driven lift fan. The lift fan, used for vertical landing and take-off, is situated behind the cockpit and contains seven bladerows, of which two are counter-rotating rotors. The aim of the analysis is to determine the maximum vibration amplitudes of the two rotor bladerows for a range of configurations and speeds. Unlike typical axial-flow compressors, a significant part of the unsteady aerodynamic excitation is due to the distortion of the inlet flow over the cockpit and fuselage, a situation that creates several low engine-order harmonics. In addition, the main blade passing harmonics, arising from the bladerows immediately upstream, also need to be considered. Both the blading and the inlet geometry are difficult to discretize, the former due to overlapping bladerows and the latter due to complexity of the aircraft geometry including the louvred doors. The forced response analysis methodology is based on using an integrated aeroelasticity model which combines a non-linear, time-accurate, viscous unsteady flow representation with a modal model of the structure. The rotor vibration response was assessed at various shaft speeds for both stationary aircraft and at a number of flight speeds and yaw angles. Wherever possible, the findings were compared against measured experimental data and good agreement was obtained in most cases. The main conclusion is the feasibility of being able to use a numerical tool as an integral part of the design process, a route that allows a much more efficient coverage of the flight envelope compared to actual rig and engine tests.

Cavitation modeling and diesel engine cylinder liners

A common occurrence of cavitation damage is the waterside pitting of a wet sleeve liner in a diesel engine. The automotive industry utilizes an ultrasonic test of 20 kHz according to ASTM standards to quantify the effectiveness of engine coolant additives to prevent damage. However, recent tests indicate a mismatch between the ultrasonic test results and actual engine test runs. The focus of this study is to generate numerical models of bubble dynamics using already published literature. In most of the published papers higher-range frequencies (ultrasonic >15 kHz) are used. It is useful to explore the results of lower excitation frequencies as the vibrating frequencies of a diesel engine liner are between 500–9000 Hz. A Rayleigh–Plesset equation, nonlinear in nature, is used to plot the relation between bubble radius and time. Plots of the numerical solution from MATLAB are compared with plots published in the literature. Results from when the frequency of excitation is changed to the liner wall frequency and the fluid properties are changed to approximate engine conditions will be presented. Future work will examine the energy released by the bubble collapse and its correlation with erosion measured as mass change in a standard test button.

EVALUATION OF MOUNT LOADS IN DYNAMIC TESTING OF A JET ENGINE

In the dynamic testing of jet engines the evaluation of loads on the mount structure is vital for comparison with finite element calculations of such testing. Measuring these loads with the help of strain gauges applied to the structure becomes difficult if the mount is overdetermined and thus not every strain gauge can be assigned to a single load direction. In this study, the overdetermined mount structure of the BR715 engine was examined at one of the three mounting points between the Boeing 717 airframe and the engine, where loads in five directions were reacted. Firstly, the dependence of five measured strains upon known static load conditions at the mounting point had to be determined. For this purpose a static calibration test was carried out where defined forces and moments in known directions were applied to the structure while the output from five strain gauges was measured accordingly. The result was the desired relationship between loads and strains in terms of a matrix, which yields the corresponding load condition of the examined mounting point if multiplied with a set of strains. The same calibration procedure was carried out with a finite element model of the mount, where direct comparison to dynamic load results from the model itself was possible. With this model the validity of the above method was shown as well as possible errors which may occur while evaluating dynamic test results. The method was found to give satisfactory results even for dynamic loading, although some inertia forces disturb the signals in dynamic testing. Finally, the results from an actual dynamic engine test were processed into loads and then compared to the simulated loads from a finite element model of the engine. Good agreement was found and the indication of any remaining discrepancies was used to update the model for an even better representation of the dynamic test loads.

Low frequency cavitation erosion

Damage of diesel engine piston sleeve liners due to cavitation of the coolant fluid can be severe. Coolant fluid additives are used to inhibit cavitation damage, and are evaluated by industry suppliers using ASTM G32-98 Standard Test Method for Cavitation Erosion Using Vibratory Apparatus. The ASTM G32-98 test procedure uses an ultrasonic horn at 20 kHz to vibrate a test button in the coolant. The test button mass loss and surface appearance are studied to sort the performance of new coolant additives. Mismatch between good lab performers and actual engine test runs has raised concerns over the current lab test. The frequency range of the current test has been targeted for investigation. A low frequency, less than 2000 Hz, test rig was built to explore the cavitation damage. The test system did produce cavitation on the surface of the test button for a period of 36 h, with minimal mass loss. The test rig experienced cyclic fatigue when test times were extended. The work is now focusing on designing a better test rig for long duration tests and on developing numerical models in order to explore the effects of cavitation excitation frequency on surface erosion.

Development of Piston-Ring for Marine Diesel Engine. Actual Engine Test Result of Piston-Ring Made from Wear Resisting Steel.

In one direction of improving the material strength of a piston-ring of a marine diesel engine, a new wear resisting steel has been made efforts to develop in the expectation that it may supersede high phosphorus gray cast iron. For the newly developed wear resisting steel (later, wear resisting steel) we carried out wear tests and scuffing tests, and analyzed its test results in comparison with those of gray cast iron. After that we manufactured piston-rings using wear resisting steel. Piston rings made from wear resisting steel were installed the actual engine, and the actual engine test was carried out for 160.8 hours. We inspected the sliding surfaces of piston-rings after 29 hours and 160.8 hours. According to the test results, the wear amount of wear resisting steel was the same or smaller than that of gray cast iron, and the sliding surfaces of piston rings were normal and no severe wear such as scuffing was observed on them.

Evidence of accelerated thermal cycling test schedules influencing the ranking of zirconia-base thermal barrier coatings

Thermal barrier coatings (TBCs) often encounter temperature cycling in the course of normal operation. In the absence of actual or simulated engine test facilities, accelerated furnace thermal cycling experiments are frequently devised to evaluate the response of various TBCs. This study, which deals with yttria-stabilized and magnesia-stabilized zirconia systems, shows that the performance of a TBC is significantly governed by the severity of the time-temperature schedule employed. More importantly, the ranking of the two zirconia-base TBCs also is influenced by the adopted thermal cycling test schedule. These findings have ramifications in the design of suitable accelerated tests for TBC evaluation.