A Development Method and Applications of the Most Severe Engine Parameters for Airworthiness Certification

2015 ◽  
Author(s):  
Huihui Li ◽  
Bin Tang
Keyword(s):  
Operating Conditions ◽  
Aircraft Engines ◽  
Rotor Speed ◽  
Commercial Aircraft ◽  
Certification Process ◽  
Development Method ◽  
Adverse Conditions ◽  
Shaft Torque ◽  
The Difference

For commercial aircraft engines, airworthiness certification is essential and the very first step before entry into service. Airworthiness requirements mainly consider the safety of the aircraft and mandate the aviation products to safely operate under all possible conditions. Therefore, during an airworthiness certification process, the relevant analyses and verifications are generally carried out by considering the most adverse operating conditions. A method for obtaining the most severe engine parameters which represent the possibly most adverse conditions is presented in this paper. Furthermore, it is used to complete the calculation of a set of most severe parameters, including rotor speed, turbine temperature, pressure, shaft torque, etc. Finally, this paper describes applications of these most severe parameters in the certification of the engine airworthiness regulation-CCAR/FAR33. Two examples are provided to illustrate the difference between using the general parameters and the most severe parameters. These examples demonstrate that application of most severe engine parameters to comply with the airworthiness requirements is the most practical way to guarantee the true safety.

scholarly journals NASA Advanced Low Emissions Combustor Program

1983 ◽  
Author(s):  
A. Goyal ◽  
E. E. Ekstedt ◽  
A. J. Szaniszlo
Keyword(s):  
Operating Conditions ◽  
Pollutant Emissions ◽  
Aircraft Engines ◽  
Test Results ◽  
Commercial Aircraft ◽  
Burning Zone ◽  
Wide Range ◽  
Fuel Staging ◽  
Improved Performance ◽  
Combustion Tests

The purpose of this program is to conduct combustion tests on lean, premixed, and prevaporized (LPP) combustor concepts designed for use in commercial aircraft engines to attain improved performance, durability, and lower pollutant emissions levels relative to current technology combustor designs. Four full annular combustors were designed for the CF6–50 engine. These concepts utilize premixing of the fuel and air, variable geometry, and fuel staging to control the equivalence ratios of the burning zone. The testing is being conducted on these four full annular combustors over a wide range of operating conditions at pressures up to actual subsonic cruise (1.16 MPa). The test results for the most promising of these combustor concepts are reported in this paper.

Production of quicklime from Ashaka limestone through calcination process

2021 ◽  
Vol 1 (2) ◽  
pp. 041-048
Author(s):  
Benson Chinweuba Udeh
Keyword(s):  
Particle Size ◽  
Critical Value ◽  
Operating Conditions ◽  
Quadratic Model ◽  
Particle Sizes ◽  
Calcination Process ◽  
Process Effects ◽  
Effects Of Temperature ◽  
The Difference ◽  
The Relationship

This study is on the production of quicklime from Ashaka limestone through calcination process. Effects of temperature, particle size and time on quicklime yield were determined. The experiment was carried out at temperatures of 800, 900, 1000, 1100 and 1200 0C, particle sizes of 80mm, 90mm, 100mm, 300mm and 425mm and times of 0.5hr, 1hr, 2hrs, 3hrs and 4hrs. Analyses of the results showed that quicklime was successfully produced from Ashaka limestone through the calcination process. Quadratic model adequately described the relationship between quicklime yield and calcination factors of temperature, particle size and time. Recorded model F-value of 134.35 implies that the model is significant. The predicted R² of 0.9597 is in reasonable agreement with the adjusted R² of 0.9844; the difference is less than the critical value of 0.2. Optimum yield of 73.48% was obtained at optima operating conditions; temperature of 1000 0C, particle size of 90 µm and time of 3 hrs.

Proportional–Integral Controller Design for Combustion-Timing Feedback, From n-Heptane to Iso-Octane in Compression–Ignition Engines

2017 ◽  
Vol 140 (5) ◽  
Author(s):  
Gabriel Ingesson ◽  
Lianhao Yin ◽  
Rolf Johansson ◽  
Per Tunestål
Keyword(s):  
Ignition Delay ◽  
Controller Design ◽  
Negative Temperature ◽  
Operating Conditions ◽  
Measurement Noise ◽  
Noise Sensitivity ◽  
Proportional Integral ◽  
Primary Reference ◽  
The Difference ◽  
Primary Reference Fuels

The problem of designing robust and noise-insensitive proportional–integral (PI) controllers for pressure-sensor-based combustion-timing control was studied through simulation. Different primary reference fuels (PRF) and operating conditions were studied. The simulations were done using a physics-based, control-oriented model with an empirical ignition-delay correlation. It was found that the controllable region in between the zero-gain region for early injection timings and the misfire region for late injection timings is strongly PRF dependent. As a result, it was necessary to adjust intake temperature to compensate for the difference in fuel reactivity prior to the controller design. With adjusted intake temperature, PRF-dependent negative-temperature coefficient (NTC) behavior gave different system characteristics for the different fuels. The PI controller design was accomplished by solving the optimization problem of maximizing disturbance rejection and tracking performance subject to constraints on robustness and measurement-noise sensitivity. Optimal controller gains were found to be limited by the high system gain at late combustion timings and high-load conditions; furthermore, the measurement-noise sensitivity was found to be higher at the low-load operating points where the ignition delay is more sensitive to variations in load and intake conditions. The controller-gain restrictions were found to vary for the different PRFs; the optimal gains for higher PRFs were lower due to a higher system gain, whereas the measurement-noise sensitivity was found to be higher for lower PRFs.

scholarly journals The Sprotte Needle and Post Dural Puncture Headache following Caesarean Section

1993 ◽  
Vol 21 (3) ◽  
pp. 280-283 ◽  
Author(s):  
A. W. Ross ◽  
C. Greenhalgh ◽  
D. P. McGlade ◽  
I. G. Balson ◽  
S. C. Chester ◽  
...  
Keyword(s):  
Caesarean Section ◽  
Population Size ◽  
Lower Incidence ◽  
Dural Puncture ◽  
Operating Conditions ◽  
Hyperbaric Bupivacaine ◽  
Post Dural Puncture Headache ◽  
The Difference ◽  
Obstetric Population

One hundred and forty-four patients receiving subarachnoid anaesthesia for caesarean section were prospectively analysed for quality of anaesthesia and the occurrence of post dural puncture headache (PDPH). Anaesthesia was administered via 24 gauge Sprotte (n = 104) and 26 gauge Quincke (n = 40) needles using hyperbaric bupivacaine 0.5% with morphine 0.2 mg. Anaesthesia was successful in 103 patients with the Sprotte needle and 38 patients with the Quincke needle, and the operating conditions were considered to be excellent. Of the 104 patients in the Sprotte needle group there were ten with PDPH (9.6%), two of which were considered severe. Of the 40 patients in the Quincke needle group there were eight with PDPH (20%), three of which were considered severe. Despite the lower incidence of headache in the Sprotte needle group, this was not statistically significant (P>0.05), due to the difference in population size. We conclude that the 24 gauge Sprotte needle is associated with a comparatively low but clinically relevant incidence of headache in the obstetric population.

scholarly journals Assessment of vehicle brake control functional stability

2021 ◽  
Vol 12 (2) ◽  
pp. 33-44
Author(s):  
Volodymyr Volkov ◽  
◽  
Igor Gritsuk ◽  
Tetiana Volkova ◽  
Volodymyr Kuzhel ◽  
...  
Keyword(s):  
Energy Consumption ◽  
Control Method ◽  
Operating Conditions ◽  
National Standards ◽  
Passenger Vehicles ◽  
The Difference ◽  
Braking Control ◽  
The Stability ◽  
Friction Surfaces

The article is devoted to the study of the influence of the brake control elements of passenger vehicles on the stability of their braking properties. The analysis of the influence of uneven braking forces on the wheels of one axle of vehicles on the deviation of the distribution of braking forces between the axles from its calculated value is carried out. When assessing the error in regulating the distribution of braking forces between the axles of vehicles, three components were taken into account: the theoretical error due to the imperfection of the selected control method (the difference between the actual calculated control characteristic from the ideal), the error created due to the instability of the ratio of the braking forces on the front and rear wheels, an additional error caused by the unevenness of the braking forces on the wheels of individual axles, since the fulfillment of the most stringent requirements of international and national standards for the efficiency of braking of vehicles and is inextricably linked with the need to increase the energy consumption of brake mechanisms. The energy consumption of braking mechanisms is understood as the ability of the latter to dissipate the greatest amount of energy of the braking machine without reducing the braking efficiency indicators to the minimum permissible level. Excessive heating of the braking mechanisms leads to a decrease in the friction coefficient μ of the friction surfaces and increased wear of the friction linings, and the brakes are the most unstable element of the braking control, which ensures the absorption and dissipation of the vehicle's energy during braking. The instability of the braking torques on the front and rear wheels, caused by a change in the coefficients of friction of friction pairs, leads not only to a change in the distribution of braking forces between the axles and individual wheels, but also to a decrease in the braking efficiency of vehicles under operating conditions. A method is proposed that makes it possible to assess the quality of regulation of the distribution of braking forces between the axles of a car, taking into account the instability of the braking forces on the wheels.

scholarly journals The influence of centrial forces on crankshaft bearing lubrication is in emergency modes of the engine of the car

2021 ◽  
Vol 12 (2) ◽  
pp. 112-121
Author(s):  
Oleksandr Khrulev ◽  
◽  
Olexii Saraiev ◽  
Iryna Saraieva ◽  
◽  
...  
Keyword(s):  
Internal Combustion Engines ◽  
Operating Mode ◽  
Internal Combustion ◽  
Technical Condition ◽  
Operating Conditions ◽  
Combustion Engines ◽  
Connecting Rod ◽  
Oil Supply ◽  
Technical Expert ◽  
The Difference

The analysis of the crankshaft bearing condition of the automotive internal combustion engines in the case of insufficiency and breakage of oil supply to them is carried out. It is noted that this fault is one of the most common causes of damage to rubbing pairs in operation. At the same time, the different groups of bearings are often damaged, which cannot be explained within the framework of existing models of plain bearing lubrication. The objective of the work is to develop a mathematical model of oil supply to connecting rod bearings in emergency mode, taking into account the characteristic features of the bearing design. The model also, depending on the nature of the damage, should help to determine and explain the causes of bearing failures if they occur in different modes when operating conditions are broken. A computational model has been developed that makes it possible to assess the effect of design differences in the features of oil supply and the action of the centrifugal forces during crankshaft rotation on the oil column in the lubrication hole where oil is supplied to the conrod bearing. Calculations of the change in time of the oil supply pressure to the connecting rod bearings for the various designs of the crankshaft lubrication holes have been performed. It is shown that, depending on the operating mode of the engine and its design, the oil pressure in front of the connecting rod bearings does not disappear immediately after oil supply failure to crankshaft. Moreover, the lower the crankshaft speed is, the longer the lubrication of the conrod bearings will continue. The calculation results are confirmed by the data of the expert studies of the engine technical condition, in which the crankshaft was wedged in the damaged main bearings was found in the absence of serious damage to the connecting rod ones. It has been found that such features of the damage correspond to an rapid breakage of the oil supply to the crankshaft in the case of such operational damage as the oil pump and pressure reducing valve failure, the oil filter seal and oil pan destruction, etc. The developed model explains the difference in lubrication conditions and in the damage feature to the main and connecting rod bearings in the emergency cases of the oil supply breakage, which are observed during operation, and helps to clarify the failure causes. This makes it possible to use the model and the obtained data when providing auto technical expert studies of the failure causes of automobile internal combustion engines This makes it possible to use the model and the obtained data when providing auto technical expert studies of the failure causes of automobile internal combustion engines when the operating conditions are broken.

scholarly journals The Effectiveness of Technical Guidance for Entrepreneurs in Small and Medium Enterprises in Facing Halal Certification

2020 ◽  
Vol 2 (2) ◽  
pp. 46-49
Author(s):  
Siska Siska ◽  
Hanifah Rahmi ◽  
Almawati Situmorang
Keyword(s):  
Small And Medium Enterprises ◽  
Market Demand ◽  
Certification Process ◽  
Guarantee System ◽  
Assurance System ◽  
Before And After ◽  
Post Test ◽  
The Difference ◽  
Medium Enterprises ◽  
Technical Guidance

Indonesia is the largest Muslim population country in the world, so the market demand for halal products is enormous. However, in fact, there are not many business actors who submit and have halal certificates, especially in small and medium enterprises. This problem can be due to lack of information and sufficient understanding to apply for a halal certificate. The aim of the research is to give technical guidance for preparing halal certification process. The manual method is used to provide training on the halal guarantee system for the preparation of the halal assurance system (HAS). The workshop began with a pre-test and then the presentation of halal assurance system material, the guidance on how to prepare and discussion. All the activities were done by online (WhatsApp group and zoom meeting). The training ended with the post-test to assess the improvement of knowledge of the. To analyze the difference, we used a paired T-test statistical method. The result of this research shows an increasing understanding of participants (p<0,05) through the comparison between before and after training. These activities conclude that the practice of technical guidance for facing halal certification is beneficial for small and medium enterprises in improving knowledge and capability of the halal certification process.

scholarly journals Brush Seal Leakage Performance With Gaseous Working Fluids at Static and Low Rotor Speed Conditions

1993 ◽  
Vol 115 (2) ◽  
pp. 397-403 ◽  
Author(s):  
J. A. Carlile ◽  
R. C. Hendricks ◽  
D. A. Yoder
Keyword(s):  
Carbon Dioxide ◽  
Pressure Drop ◽  
State Theory ◽  
Operating Conditions ◽  
Rotor Speed ◽  
Working Fluids ◽  
Brush Seal ◽  
Annular Seal

The leakage performance of a brush seal with gaseous working fluids at static and low rotor speed conditions was investigated. This report includes the leakage results for air, helium, and carbon dioxide at several bristle/rotor interferences. In addition, the effects of packing a lubricant into the bristles and also of reversing the pressure drop across the seal were investigated. Results were compared to that of an annular seal at similar operating conditions. In order to generalize the results, they were correlated using corresponding state theory. The brush seal tested had a bore diameter of 3.792 cm (1.4930 in.), a fence height of 0.0635 cm (0.025 in.), and 1800 bristles/cm-circumference (4500 bristles/in.-circumference). Various bristle/rotor radial interferences were achieved by using a tapered rotor. The brush seal reduced the leakage in comparison with the annular seal, up to 9.5 times. Reversing the pressure drop across the brush seal produced leakage rates approximately the same as that of the annular seal. Addition of a lubricant reduced the leakage by 2.5 times when compared to a nonlubricated brush seal. The air and carbon dioxide data were successfully correlated using the corresponding state theory. However, the helium data followed a different curve from the air and carbon dioxide data.

Defect Detection in an Annular Swirl-Burner-Array by Optical Measuring Exhaust Gases

2016 ◽  
Author(s):  
Henrik von der Haar ◽  
Ulrich Hartmann ◽  
Christoph Hennecke ◽  
Friedrich Dinkelacker ◽  
Joerg R. Seume
Keyword(s):  
Power Distribution ◽  
Measurement Techniques ◽  
Aircraft Engine ◽  
Operating Conditions ◽  
Maximum Output ◽  
Aircraft Engines ◽  
Combustion Chambers ◽  
Scaled Model ◽  
Ongoing Research ◽  
Exhaust Gases

Defects in combustion chambers of aircraft engines might have an impact on the reliability of the downstream turbine and the machine’s performance. Detecting failures in the combustion chamber of an aircraft engine during operation may improve the resource management and the availability of the system. Aim of the ongoing research project is to find an approach to evaluate the state of the jet engine by analyzing the temperature and emissions field in the exhaust jet. This investigation is part of the collaborative research center SFB 871. The SFB 871 deals with the improvement of the regeneration process of complex capital goods such as aircraft engines. Maintenance, repair, and overhaul processes would be more efficient if the internal status of the engine would be known while still on the wing before it is disassembled. The feasibility of this approach is investigated for a pilot scaled model combustor, which provides optical access and allows the selection of “defined errors” in the combustor. It consists of an atmospheric tubular combustor with an array of eight premixed swirl burners with a maximum output of 160 kW. The operating conditions of one of the eight burners concerning power and air-fuel ratio, can be controlled. A power distribution between the burners is typical fault in an aircraft combustor and will be investigated in this study. It is observed that it is possible to determine small deviations by measuring density profiles applying a tomographic background-oriented schlieren (BOS) technique behind the combustor. Additionally, particle image velocimetry is used to measure differences in the velocity field of the exhaust gases. This study shows that a minimum power deviation of one burner in an array of a total of eight burners is detectable in the exhaust plane with the above mentioned measurement techniques.

Contactless Shaft Torque Detection for Wide Range Performance Measurement of Exhaust Gas Turbocharger Turbines

2013 ◽  
Vol 136 (6) ◽  
Author(s):  
Bernhardt Lüddecke ◽  
Dietmar Filsinger ◽  
Jan Ehrhard ◽  
Bastian Steinacher ◽  
Christian Seene ◽  
...  
Keyword(s):  
Internal Combustion Engine ◽  
Combustion Engine ◽  
Internal Combustion ◽  
Sensitivity Study ◽  
Operating Conditions ◽  
Measuring System ◽  
Sensor Calibration ◽  
Torque Measurement ◽  
Wide Range ◽  
Shaft Torque

Turbochargers develop away from an auxiliary component—being “off the shelve”—towards an integrated component of the internal combustion engine. Hence, increased attention is paid to the accuracy of the measured turbine and compressor maps. Especially turbine efficiency measurement under engine-relevant operating conditions (pulsed flow) is recently receiving increased attention in the respective research community. Despite various turbine map extrapolation methods, sufficient accuracy of the input test data is indispensable. Accurate experimental data are necessary to achieve high quality extrapolation results, enabling a wide range and precise prediction of turbine behavior under unsteady flow conditions, determined by intermittent operation of the internal combustion engine. The present work describes the first application of a contactless shaft torque measurement technique—based on magnetostriction—to a small automotive turbocharger. The contactless torque measuring system is presented in detail and sensor principle as well as sensor calibration are illustrated. A sensitivity study regarding sensor position influences onto sensor signal proves the robustness and very good repeatability of the system. In the second part of the paper, steady state experimental results from operation on a conventional hot gas test stand over a wide map range are presented. These results are validated against full turbine stage (adiabatic as well as diabatic) CFD results as well as against “cold” efficiency measurements, based on measured inlet and outlet temperatures. The influence and relevance of bearing friction for such measurements is underlined and the improvements on this matter—achieved by direct torque measurement—are demonstrated.

Sign in / Sign up

Export Citation Format

Share Document