Engine Test System Research Articles

Liquid hydrogen cavitation analysis inside an oblique globe valve

Liquid hydrogen is widely used in the rocket engine test system as a fuel, and the fueling process of liquid hydrogen is controlled by the oblique globe valve installed in the liquid hydrogen main pipeline. As LH2 is transported through the oblique globe valve, cavitation has the tendency to occur near the throttling region where fluid flow causes the local static pressure to be lower than the saturated vapor pressure, especially during opening and closing process. In this paper, the cavitation dynamic evolution and axial force for the whole valve disc during opening and closing process of an oblique globe valve are investigated by the dynamic mesh and UDF technology. The results reveal that the cavitation evolution during opening process is divided into three stages including cavitation inception, cavitation development and cavitation full development. The axial force for the whole valve disc during the cavitation evolution process is increased first and then decreased as the time goes on. The unbalanced pressure distribution on the bottom of valve disc is harmful to the response of the valve disc at its maximum displacement. This work is of significance for the cavitation control and structural design of liquid hydrogen oblique globe valves.

Study of Scavenging and Combustion Processes for Small Two-Stroke Aviation Heavy Fuel Direct Injection Engines

Heavy-fuel aviation piston engines (HF-APEs) are widely used in general aviation and unmanned aerial vehicle (UAV) due to their safety and fuel economy. This paper describes a numerical and experimental study of scavenging and combustion processes on a 2-Stroke Direct Injected HF-APEs for light aircraft, with its cylinder specifically designed as cross scavenging. A 3-Dimentional transient model of in-cylinder flow and combustion process is established by the Forte platform, and the engine test system is set up. By comparing the simulation results to the experimental results, it showed that multi-ports cross scavenging can generate unbalanced aerodynamic torque in the cylinder. In the compression process, the swirl ratio (SR) gradually increases, and the peak SR reaches 15. Moreover, approximately 25% of exhaust residual gas in the cylinder is conducive to the fuel atomization and evaporation process in a high-altitude environment. When the injection timing is between −8 °CA and −16 °CA, the engine has the optimal power and economy performance at different altitudes. Finally, when the injection advance angle moves forward by 4 °CA, the maximum pressure increases by 2 MPa, with the rising rate decreasing gradually. The results have important significance for the development of the combustion system of small 2-Stroke Direct Injected HF-APEs.

Structural reliability design of liquid oxygen supply pipeline based on fluid-solid-thermal coupling

Liquid oxygen supply pipeline is a key part of liquid oxygen kerosene engine test system. If leakage occurs, it will cause flow measurement error and affect the accuracy of test data. Therefore, in the design of liquid oxygen supply pipeline, the fluid solid thermal coupling simulation analysis method is used to analyze the stress of “Z” bend, vessel bottom elbow and balance device elbow pipeline of the supply pipeline in the process of ultra-low temperature fluid flow, the optimal laying scheme of the “Z” bend route is obtained, and it is verified that the added elbow pipeline fixing support structure can effectively resist the blind plate force and improve the pipeline reliability, which provides an important reference for the structural design of liquid oxygen supply pipeline.

Modeling, simulation and experimental study of squeeze engine system

Taking the squeeze engine system as the research object, its dynamic characteristics are simulated and experimentally studied. Based on the idea of modular modeling, the dynamic model of engine components is established, and the system simulation model is constructed combined with the engine test system. The whole working condition dynamic simulation of extrusion engine is studied, and the actual ignition test is carried out to verify the whole working condition dynamic simulation of engine. The simulation and test results show that the dynamic simulation results of the engine under all working conditions are in good agreement with the test data, which verifies the accuracy of the simulation model.

Design and Implementation of UAV Engine Test System

To meet the testing requirements of small UAV piston engine, a virtual instrument-based UAV engine test system is designed. This system has the capability of on-line testing on engine even without the UAV system-wide support. With virtual instruments, serial analog-to-digital conversion and other new technologies, it can replace the ground control station to control the engine; realize rapid and portable testing as well as integrated display of the engine performance parameters; and based on the testing data, perform fault analysis and provide maintenance instructions when appropriate. The system covers the shortage of existing test methods, and improves the efficiency of UAV engine system test in field operations.

Effects of equivalence ratio and CNG addition on engine performance and emissions in a dual sequential ignition engine

Compared to widening usage of CNG in commercial gasoline engines, insufficient but increasing number of studies have appeared in the open literature during last decades, while engine characteristics need to be quantified in exact numbers for each specific fuel and engine. CNG usage in spark-ignition engine offers many advantages such as high specific power outputs, knock resistance, and low CO2 emission. Engine performance and emissions are strong functions of equivalence ratio. This study focuses on determination of the effects of equivalence ratio on engine performance and emissions for a unique commercial engine for three fuels of gasoline, CNG, and gasoline–CNG mixture (90%–10%: G9C1). For this aim, the tests and the three-dimensional in-cylinder combustion computational fluid dynamics analyses were employed in quantification of engine characteristics at wide open throttle position. Equivalence ratios were defined between 0.7 and 1.4. The engine’s maximum torque speed of 2800 r/min was examined. The tested commercial engine is an intelligent dual sequential ignition engine which has unique features such as diagonally positioned two spark-plugs, dual sequential ignition with variable timing and asymmetrical combustion chamber. This gasoline engine was equipped with an independent CNG port-injection system and a specific engine control unit for CNG. In addition, the engine test system has a concomitant dual fuel delivery system that supplies gas fuel into intake airline while liquid gasoline is injected behind the intake valve. Other than testing the engine, the three-dimensional in-cylinder combustion computational fluid dynamics analyses were performed in Star-CD/es-ice software for the three fuels. The CFD model was built by using renormalization group equations, k–ε turbulence model, and G-equation combustion model. Computational fluid dynamics analyses were run for the compression ratio of 10.8:1, equivalence ratio of 1.1, and engine’s maximum torque speed of 2800 r/min. Test results show that brake torque for all fuels increases rapidly from the lean blend to the rich blend. The brake-specific fuel consumption for all fuels decreases from Φ = 0.7 through the stoichiometric region and then slightly increases up to Φ = 1.4. The volumetric efficiencies for three fuels have similar decreasing trend with respect to equivalence ratio. Overall, CNG addition decreases the performance values of torque, brake-specific fuel consumption, volumetric efficiency, brake thermal efficiency, while it decreases emissions of CO2, CO, HC, except NOx. Engine model results show that the maximum in-cylinder pressure is 72 bar at 722 crank angle degree (CAD), 68 bar at 730 CAD, and 60 bar at 735 CAD for gasoline, CNG, and G9C1, respectively. The cumulative heat release for gasoline is 9.09% higher than G9C1, while G9C1 is 15.71% higher than CNG. The CO2 mass fraction for gasoline is about 22.58% lower than G9C1, while it is 40.32% higher than CNG. The maximum mass fraction value of CO is 0.21, 0.17, and 0.08 for gasoline, CNG, and G9C1, respectively. The CO for G9C1 is overall 60.04% lower than CNG and 67.45% lower than gasoline. At maximum point, HC for G9C1 is 31.43% and 71.43% higher than gasoline and CNG, respectively. CNG has the highest level of NOx formation. Maximum NOx mass fractions are 0.0098, 0.0070, and 0.0043 for CNG, G9C1, and gasoline, respectively. After the ignition, the flame development is completed at 1.07, 1.18, and 1.28 ms for gasoline, G9C1, and CNG, respectively. Flame velocities are 28.52, 30.93, and 34.11 m/s for CNG, G9C1, and gasoline, respectively, at 2800 r/min and Φ = 1.1. When the time between ignition moment and top dead center moment is considered, the increment rate of flame center temperature is 904.19, 884.10, and 861.77 K/s for CNG, gasoline, and G9C1, respectively. The highest temperature increment rate occurs for CNG.

A gaseous emissions analysis of commercial aircraft engines during test-cell run

This study presents an analysis of the seventeen complete measurements of gaseous emissions of eleven different CFM56-7B26 turbofan engines during the regular test-cell runs. A novel measurement setup is established in which the sample probe is located immediately behind the low pressure turbine rotor. Recording a total of 49,190 data points for 26 raw variables (obtained from both the emission measurement and engine test systems), emissions are characterized with stable engine power settings representing main flight phases, as well as fuel flow of the engine during the entire run. Carbon monoxide and total hydrocarbons concentrations are found to be a strong function of fuel flow at low power settings, and nitrogen oxides emissions at high power settings. In comparison to emission indices provided by the International Civil Aviation Organization, the current study results in considerably higher carbon monoxide and hydrocarbons under idle conditions, with relatively lower nitrogen oxides at almost all of the power settings. On the other hand, significant differences in levels of nitrogen oxides are observed from one engine test to another, emphasizing the effects of the engine and the ambient air conditions. The average NO2/NOx are found to be 40% (±16) and 32% (±9) for ground and approach idles, respectively, while at high power settings, above N1 = 64%, the NO2/NOx ratios stabilize at around 5–6% (±1–2). Since the emissions were monitored and recorded during the entire engine run, the start and end moments (cold and hot idles) of the tests are compared. The average carbon monoxide and hydrocarbons concentrations are found to be 14% and 35% lower at hot ground idles compared to cold ground idle, with the results for nitrogen oxides and carbon dioxide being 22% and 0.5% higher. The effect of ambient air temperature on emissions are also investigated and quantified for certain temperature ranges. It has been determined that the hydrocarbons and carbon monoxide concentrations decrease with ambient air temperature, yet the nitrogen oxides and carbon dioxide concentrations increase. Findings related to ambient air temperature are found to corroborate the findings related to running at cold and hot idles, linking to a positive correlation between the ambient air temperature, the combustor inlet temperature and the exhaust gas temperature.

The Design of the Test Control System of Small Piston Aircraft Engine

For the engine maintenance enterprises, the test of aeroengine test can detect the performance of the product more accurately, but the engine testing work is a weak link. Conventional piston aircraft engine test system is the simulation instrument, according to the observed by human eyes, manual way to complete data collection work, this test system is inefficient. The engine bench test automatic measurement and control and monitoring system based on computer control is the inevitable trend of its development. Data acquisition module transmits the real-time data from the engine sensor installed on the different parts to the PC through CAN bus and display on the PC. The engine test bed control system and data acquisition system simplifies the system structure and obviously improves the test level and efficiency of the system.

Information technology in engine test systems

Vehicle manufacturers are under increasing pressure to improve engine performance, especially in terms of fuel consumption and exhaust emissions. Furthermore, there is a growing need to improve reliability, increase durability, and reduce overall servicing costs. To achieve these targets new and improved design and manufacturing techniques have had to be devised. It can be seen that automation of the engine test facility is desirable from two points of view: firstly to improve the working conditions of the operator, and secondly to provide better quality data for the development engineer. It is also to be hoped that working efficiency is increased, so reducing labour costs. This paper describes work currently in progress to achieve such a level of automation. It is in the nature of a pilot scheme to assess the technical, commercial, and human aspects of automating engine test facilities. Here specific technical aspects of the overall problem which relate to information technology only are discussed.

An Instrumented Diesel Engine System for Research and Education of Alternative Fuels

Abstract. This article reports the development and demonstration of an instrumented diesel engine test system for the assessment of power performance, fuel efficiency, and exhaust emissions of alternative diesel fuels. The system was composed of a 4-cylinder diesel engine (60 kW), water-brake dynamometer (294.2 kW), fuel stand, 5-gas emission analyzer, two computers, a data acquisition system, and various sensors to measure the engine performance parameters. The fuel stand allowed for changing the direction of the fuel supply between the diesel fuel tank and the alternative fuel tank, and measured the instantaneous fuel consumption. The data on engine performance, fuel consumption, and exhaust emissions were monitored and recorded as a text file for analyses and comparisons. The elements of the engine system and fuel test procedure were demonstrated to 40 students during the testing of biodiesel-diesel fuel blends. The students’ knowledge of the diesel engine test system components and fuel test procedure were evaluated through a survey instrument administered before and after the laboratory demonstrations. The survey results indicated that the engine test stand was effective in demonstrating to college students the significant parameters for the evaluation of alternative fuels.

0239 局所接触型マイクロ波加熱式燃料噴射装置を搭載したエンジン性能試験機の開発(OS14-2 微粒化および燃焼現象の解析,オーガナイズドセッション 14:「微粒化および燃焼現象の解析」)

0239 局所接触型マイクロ波加熱式燃料噴射装置を搭載したエンジン性能試験機の開発(OS14-2 微粒化および燃焼現象の解析,オーガナイズドセッション 14:「微粒化および燃焼現象の解析」)

A Study on Performance and Emissions of a DI Diesel Engine Using Oxidation of Diesel Additive Blends

The FC2000 automatic engine test system for control and measuring the engine speed, torque, power, fuel consumption, temperature, pressure, and flow rate of different kinds of parameters. Different kinds of sensor output signal, focused on CAN intelligent module regulate into standard digital signal, through the bus network for transmission, facilitate the centralized management. The engine was burning, E15 E20, the mixed fuel, as a mixing of acetate ethylene glycol proportion of the increase, the economy improved. In 2200 RPM, 2800 RPM, 3600 RPM load characteristics, with a acetate ethylene glycol mixing ratio increases, CO emissions in the small and medium-sized load conditions gradually increase in big load conditions gradually improve.

Research about Detection System of Hydrogen Engine

This paper describes a detection system design method of hydrogen engine based on LabVIEW. In order to understand the characteristics and working status of hydrogen fuel engine, we have developed a set of hydrogen fuel engine test system. In the system, LabVIEW is used as the software and DAQ PCI-1802H is the hardware, which mainly realizes the collection, testing, comparison analysis of engine signals and its feature parameters. It has strong functions of signal analysis and processing as well as nice user interface.

Concurrent Engineering in Engine Development

AVL is offering sophisticated engine engineering services, instrumentation and engine test systems to companies all over the world. This demands on the one hand to develop high quality products and on the other hand to be a partner in the concurrent product and process engineering programmes of customer.This paper describes how AVL applies its services within the customers concurrent engineering teams. The interactions between design and simulation work as a first step to meet the target of “analytical prototyping” are explained.