Modeling and Simulation of a Cold-Engine Test Stand Driveline With Experimental Comparisons

2006 ◽  
Author(s):  
Kamran A. Gul ◽  
Douglas E. Adams
Keyword(s):  
Fuel Injection ◽  
Cold Test ◽  
Forced Response ◽  
Test Stand ◽  
Torsional Vibrations ◽  
Engine Test ◽  
Response Characteristics ◽  
Noise Characteristics ◽  
Torque Measurements ◽  
The Impact

There is a need to develop cold-engine test stands for use in diagnosing cylinder faults and measuring gear noise given the new quieter fuel injection systems in modern engines. When engines run hot, these characteristics are not easily measured. By running the unfired cold-engine as a load using an electric motor and driveline, torque measurements can be used to diagnose assembly faults, damage and noise characteristics. In this paper, two cold-engine test stand drivelines are considered. Both stands experience large torsional vibrations excited by the various engine harmonics. Engine fault diagnosis becomes a challenge when these torsional vibrations degrade the measured torque signals. To solve this problem of torsional vibrations, an engine test stand model is developed to understand the system dynamics and analyze the free and forced response characteristics of the system. The model is used to predict the impact of the changes made to the test stand driveline and the trends observed in the simulation results are compared with experimental results for model validation. It is shown that based on model sensitivity analysis the changes made to the driveline parameters help to reduce the amplitude of the driveline resonances considerably. The developed model can be used to design a cold test stand for production diagnostics.

Measured Torsional Vibration Characteristics of a 100 Megawatt Wind Tunnel Drive Line

1999 ◽  
Author(s):  
James M. Corliss ◽  
H. Sprysl
Keyword(s):  
Steady State ◽  
Damping Ratio ◽  
Forced Response ◽  
Operating Conditions ◽  
Pulse Load ◽  
Torsional Vibrations ◽  
Variable Frequency Drive ◽  
Steady State Operation ◽  
Torque Measurements ◽  
Torsional Analysis

Abstract A new 100 MW (135,000 Hp) adjustable speed drive system has recently been installed in the NASA Langley National Transonic Facility. The 100 MW system is the largest of its kind in the world and consists of a salient pole synchronous motor powered by a 12-pulse Load Commutated Inverter variable frequency drive. During system commissioning the drive line torsional vibrations were measured with strain gages and a telemetry-based data acquisition system. The torque measurements included drive start-up and steady-state operation at speeds where the drive motor’s pulsating torques match the drive line’s torsional natural frequency. Rapid drive acceleration rates with short dwell times were effective in reducing torsional vibrations during drive starts. Measured peak torsional vibrations during steady-state operation were comparable to predicted values and large enough to produce noticeable lateral vibrations in the drive line shafting. Cyclic shaft stresses for all operating conditions were well within the fatigue limits of the drive line components. A comparison of the torque measurements to an analytical forced response model concluded that a 0.5% critical damping ratio was appropriately applied in the drive line’s torsional analysis.

Structural Dynamics with Parameter Uncertainties

1987 ◽  
Vol 40 (3) ◽  
pp. 309-328 ◽  
Author(s):  
R. A. Ibrahim
Keyword(s):  
Structural Dynamics ◽  
Structural Parameters ◽  
Normal Modes ◽  
Forced Response ◽  
Experimental Investigations ◽  
Continuous Systems ◽  
Parameter Uncertainties ◽  
Response Characteristics ◽  
Random Eigenvalues ◽  
The Impact

The treatment of structural parameters as random variables has been the subject of structural dynamicists and designers for many years. Several problems have been involved during the last few decades and resulted in new theorems and interesting phenomena. This paper reviews a number of topics pertaining to structural dynamics with parameter uncertainties. These include direct problems such as random eigenvalues and random responses of discrete and continuous systems. The impact of these problems on related areas of interest such as sensitivity of structural performance to parameter variations, design optimization, and reliability analysis is also addressed. The paper includes the results of experimental investigations, the phenomenon of normal modes localization, and the effect of mistuning of turbomachinery blades on their flutter and forced response characteristics.

scholarly journals The influence of particulate contamination in diesel fuel on the damage to fuel injection systems

2019 ◽  
Vol 177 (2) ◽  
pp. 76-82
Author(s):  
Zbigniew STĘPIEŃ
Keyword(s):  
High Pressure ◽  
Fuel Injection ◽  
Engine Test ◽  
Diesel Fuels ◽  
Particulate Contamination ◽  
Measurement Results ◽  
The Impact ◽  
Proper Operation ◽  
Type Fuel

The impact of various size particulate contamination on the process of accelerated wear followed by damage to the fuel injection sys-tem has been studied in long-term tests on an engine test stand. Also processes of tribological wear of working components of fuel injec-tors and of high pressure pumps material has been characterised. Measurement results of particulate contamination in diesel fuels available on the Polish market have been presented, referred to requirements of the PN-EN590 standard and of the Worldwide Fuel Charter. In the summary attention has been drawn to the growing problem of particulate contamination in fuels available on the market, and in particular their threat to durability and proper operation of increasingly complex and precisely manufactured HPCR type fuel injection systems.

Experiments on Complex Repetitive Impact Dynamics of a Built-Up Beam Structure

2006 ◽  
Author(s):  
Elizabeth K. Ervin ◽  
Jonathan A. Wickert
Keyword(s):  
Experimental System ◽  
Mapping Method ◽  
Problem Area ◽  
Forced Response ◽  
Beam Structure ◽  
Response Characteristics ◽  
Time Histories ◽  
Impact Phenomena ◽  
Repetitive Impact ◽  
The Impact

This paper investigates the experimental dynamics of a beam structure that supports an attached rigid body and that can impact a comparatively compliant base structure. The problem area is motivated by impact phenomena that are observed in certain structures internal to nuclear reactors. The assembly is subjected to base excitation at specified frequency and acceleration, and the resulting displacement and velocity time histories are recorded and used to obtain spectra, phase diagrams, and Poincare´ sections. The measurements validate simulation results obtained by using a constraint and modal mapping method based on the two sets of modes when the structure is in-contact, and when it is not-in-contact. Generalized coordinates are mapped across the impact discontinuities in the modal representation. The forced response simulation predicts the test specimen's response over a range of excitation frequencies. The specimens are fabricated as single integral structures from acrylnitrile butadene styrene plastic through rapid prototyping technology in order to eliminate the undesirable dissipation and flexibility arising from joints and connections. The experimental system can exhibit complex response characteristics, and the influences on complexity of deadband clearance and of asymmetry in the point of impact are examined in the experiments.

Modeling and Excitation Torque Estimation of an Engine Cold-Test Stand for Evaluating Driveline Design and Fault Diagnostics

2007 ◽  
Author(s):  
Kamran A. Gul ◽  
Douglas E. Adams
Keyword(s):  
Diagnostic Test ◽  
Vibration Suppression ◽  
Cold Test ◽  
Gas Pressure ◽  
Test Stand ◽  
Torsional Vibrations ◽  
Fuel Injector ◽  
Torque Estimation ◽  
Engine Excitation ◽  
Injector Pulse

The fault detection process becomes difficult in engine cold-testing when the test stands undergo torsional vibrations excited by various engine harmonics. In the context of vibration suppression and assembly faults diagnostics, this paper focuses on three main aspects: cold-test stand modeling and validation, estimation of cold-engine excitation torque, and evaluation of a fuel injector pulse diagnostic test. To analyze the vibratory torque of the cold-test stand driveline, an engine excitation model comprising of inertia torque and unfired gas pressure torque is needed. The gas pressure torque cannot be determined in the absence of engine gas pressure measurements. It is shown that this excitation torque can be estimated by assuming that the net torque during the unfired engine cycle is zero and by utilizing the firing engine gas pressure torque in the combustion stroke. The estimated excitation torque is employed to validate models of different cold-test stands and also to examine various driveline design alternatives. Using embedded sensitivity functions, it is found that by changing the inertia and stiffness of the rubber coupling, the torsional vibrations can be suppressed. Finally, the modified design is evaluated for an injector pulse diagnostic test. It is shown that the design modifications can also enhance sensitivity to faults if the injector pulse test is carried out at higher speeds.

Industrial Trent Combustor — Combustion Noise Characteristics

1999 ◽  
Author(s):  
Thomas Scarinci ◽  
John L. Halpin
Keyword(s):  
Fuel Injection ◽  
Power Level ◽  
Technical Problem ◽  
Combustion Noise ◽  
Ambient Conditions ◽  
Noise Mapping ◽  
Noise Characteristics ◽  
Lean Premixed ◽  
In Series ◽  
Three Stages

Thermoacoustic resonance is a difficult technical problem that is experienced by almost all lean-premixed combustors. The Industrial Trent combustor is a novel dry-low-emissions (DLE) combustor design, which incorporates three stages of lean premixed fuel injection in series. The three stages in series allow independent control of two stages — the third stage receives the balance of fuel to maintain the desired power level — at all power conditions. Thus, primary zone and secondary zone temperatures can be independently controlled. This paper examines how the flexibility offered by a 3-stage lean premixed combustion system permits the implementation of a successful combustion noise avoidance strategy at all power conditions and at all ambient conditions. This is because at a given engine condition (power level and day temperature) a characteristic “noise map” can be generated on the engine, independently of the engine running condition. The variable distribution of heat release along the length of the combustor provides an effective mechanism to control the amplitude of longitudinal resonance modes of the combustor. This approach has allowed the Industrial Trent combustion engineers to thoroughly “map out” all longitudinal combustor acoustic modes and design a fuel schedule that can navigate around regions of combustor thermoacoustic resonance. Noise mapping results are presented in detail, together with the development of noise prediction methods (frequency and amplitude) that have allowed the noise characteristics of the engine to be established over the entire operating envelope of the engine.

scholarly journals Active vorticity control in a shear flow using a flapping foil

1994 ◽  
Vol 274 ◽  
pp. 1-21 ◽  
Author(s):  
R. Gopalkrishnan ◽  
M. S. Triantafyllou ◽  
G. S. Triantafyllou ◽  
D. Barrett
Keyword(s):  
Reynolds Number ◽  
Vortex Formation ◽  
Interaction Patterns ◽  
Energy Extraction ◽  
Stable Pattern ◽  
Torque Measurements ◽  
Reverse Circulation ◽  
Visualization Experiments ◽  
Oscillating Foil ◽  
The Impact

It is shown experimentally that free shear flows can be substantially altered through direct control of the large coherent vortices present in the flow.First, flow-visualization experiments are conducted in Kalliroscope fluid at Reynolds number 550. A foil is placed in the wake of a D-section cylinder, sufficiently far behind the cylinder so that it does not interfere with the vortex formation process. The foil performs a heaving and pitching oscillation at a frequency close to the Strouhal frequency of the cylinder, while cylinder and foil also move forward at constant speed. By varying the phase of the foil oscillation, three basic interaction modes are identified. (i) Formation of a street of pairs of counter-rotating vortices, each pair consisting of one vortex from the initial street of the cylinder and one vortex shed by the foil. The width of the wake is then substantially increased. (ii) Formation of a street of vortices with reduced or even reverse circulation compared to that of oncoming cylinder vortices, through repositioning of cylinder vortices by the foil and interaction with vorticity of the opposite sign shed from the trailing edge of the foil. (iii) Formation of a street of vortices with circulation increased through merging of cylinder vortices with vortices of the same sign shed by the foil. In modes (ii) and (iii) considerable repositioning of the cylinder vortices takes place immediately behind the foil, resulting in a regular or reverse Kármán street. The formation of these three interaction patterns is achieved only for specific parametric values; for different values of the parameters no dominant stable pattern emerges.Subsequently, the experiments are repeated in a different facility at larger scale, resulting in Reynolds number 20000, in order to obtain force and torque measurements. The purpose of the second set of experiments is to assess the impact of flow control on the efficiency of the oscillating foil, and hence investigate the possibility of energy extraction. It is found that the efficiency of the foil depends strongly on the phase difference between the oscillation of the foil and the arrival of cylinder vortices. Peaks in foil efficiency are associated with the formation of a street of weakened vortices and energy extraction by the foil from the vortices of the vortex street.

Mistuning and Damping of a Radial Turbine Wheel. Part 1: Fundamental Analyses and Design of Intentional Mistuning Pattern

2021 ◽  
Author(s):  
Alex Nakos ◽  
Bernd Beirow ◽  
Arthur Zobel
Keyword(s):  
High Stress ◽  
Forced Response ◽  
Experimental Investigations ◽  
Detailed Knowledge ◽  
Turbine Wheel ◽  
Operation Conditions ◽  
Radial Turbine ◽  
Influence Coefficients ◽  
Modes Of Vibration ◽  
The Impact

Abstract The radial turbine impeller of an exhaust turbocharger is analyzed in view of both free vibration and forced response. Due to random blade mistuning resulting from unavoidable inaccuracies in manufacture or material inhomogeneities, localized modes of vibration may arise, which involve the risk of severely magnified blade displacements and inadmissibly high stress levels compared to the tuned counterpart. Contrary, the use of intentional mistuning (IM) has proved to be an efficient measure to mitigate the forced response. Independently, the presence of aerodynamic damping is significant with respect to limit the forced response since structural damping ratios of integrally bladed rotors typically take extremely low values. Hence, a detailed knowledge of respective damping ratios would be desirable while developing a robust rotor design. For this, far-reaching experimental investigations are carried out to determine the damping of a comparative wheel within a wide pressure range by simulating operation conditions in a pressure tank. Reduced order models are built up for designing suitable intentional mistuning patterns by using the subset of nominal system modes (SNM) approach introduced by Yang and Griffin [1], which conveniently allows for accounting both differing mistuning patterns and the impact of aeroelastic interaction by means of aerodynamic influence coefficients (AIC). Further, finite element analyses are carried out in order to identify appropriate measures how to implement intentional mistuning patterns, which are featuring only two different blade designs. In detail, the impact of specific geometric modifications on blade natural frequencies is investigated.

Reduction of Fuel Utilization Through Oxygen-Enriched Combustion in a Reheat Furnace Pusher-Type

2021 ◽  
Author(s):  
Francisco J. Martinez Zambrano ◽  
Armin K. Silaen ◽  
Kelly Tian ◽  
Joe Maiolo ◽  
Chenn Zhou
Keyword(s):  
Heat Flux ◽  
Fuel Injection ◽  
Combustion Process ◽  
Oxygen Enrichment ◽  
Rolling Temperature ◽  
Heating Zone ◽  
Reheat Furnace ◽  
Steel Slabs ◽  
The Impact ◽  
Reheating Process

Abstract Steelmaking is an energy-intensive process. Thus, energy efficiency is highly important. Several stages of steelmaking involve combustion processes. One of the most energy-consuming processes in steelmaking is the slab reheating process in a reheat furnace (RF). The energy released by fuel combustion is used to heat steel slabs to their proper hot-rolling temperature. The steel slabs move through the reheat furnace passing the three stages of heating called: Preheating Zone (PZ), Heating Zone (HZ), and Soaking Zone (SZ) to finally leave the discharge door at a rolling temperature of 2375 °F. One way to improve a reheat furnace’s fuel consumption is by implementing oxygen-enriched combustion. This study investigates the implementation of oxygen-enriched combustion in a pusher-type reheat furnace. The increment of oxygen in the combustion process allows for increasing the furnace gas temperature. Consequently, the oxygen enrichment approach allows for the reduction of fuel injection. The principal goal of this investigation is to model the combustion-based on oxygen-enrichment and develop parametric studies of fuel injection rates. The different simulations aim to match the slab heat flux profile of the industrial reheat furnace pusher-type. Computational fluid dynamics are used to generate the slab heat flux distribution. To reach more uniform slab heating, oxygen and fuel ports were alternated. Also, injection angles were modified to optimize slab heating and avoid the impact of hot spots. Thermocouple readings of the industrial reheat furnace are compared to simulation results. The results determined that 40–45% fuel reduction can be achieved.

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