Combustor Operability and Performance Verification for HIFiRE Flight 2

HIFiRE (Hypersonic International Flight Research Experimentation) is a joint flight test program supported by the US Air Force Research Laboratory (AFRL) and the Australian Defence Science and Technology Organisation (DSTO). One of the main program goals is to gather basic research data on aspects of hypers onic flight not easily accessible to ground testing. Flight one focuses primarily on integration of instrumentation on the test vehicle, with application to boundary layer transition and shock interaction experiments. The HIFiRE 1 payload consists of a blunted 7° half angle cone and a cylinder/33° flare configuration. The payload will be boosted to Mach 8 utilizing a two stage Terrier-Orion sounding rocket. The payload was designed and manufactured to achieve the desired boundary layer transition and shock boundary layer interaction properties and collect the required data. Extensive analysis and ground testing was conducted to ensure the payload will survive the expected flight environment. The HIFiRE 1 launch campaign is scheduled for March 2010. A number of valuable lessons learned during the development of HIFiRE 1 are included in this paper. I. Introduction HIFiRE is a cooperative flight test program between the United States and Australia. The goal of this program is to advance technologies associated with hypersonic flight. Special emphas is is placed on exploring phenomena not readily accessible to ground tests. Fli ght one will focus on instrumentation an d telemetry systems to be used for flights occurring later in the program. The primary objec tive of HIFiRE 1 is to determine the feasibility of applying high-bandwidth instrumentation to aero-thermal flight measurements for short duration hypersonic flights at Mach numbers up to eight. The experiment will determine the suitability and survivability of multiple instrumentation types in this environment. The experiments will be incorporated into the nose cone of a Terrier-Orion launch vehicle 1 . This paper will refer to the nose cone as the “payload.” The measurement of three aero-thermal phenomena will serve to assess the performance of the instrumentation. The corresponding sub-experiments are, in order of priori ty, boundary layer transition (BLT), turbulent separated shock boundary layer interaction (SBLI), and optical measurement of mass capture (OMC). This paper describes the design, manufacture, integration and ground testing of the payload. It also includes valuable lessons that were learned during this process. The scientific motivations for the primary and secondary experiments on HIFiRE 1 have been discussed in a number of published papers 2,3,4,5,6,7,8,9 and will not be repeated here. Design parameters critical to the BLT experiment have been derived from past correlations, computational analyses and ground testing. The most critical paramete rs affecting the BLT experiment are surface roughness and step/gap sizes at and between payload sections. The most restrictive values were 0.08mm for an allowable discrete roughness and 0.001mm root mean square (rms) roughness at the nosetip (relaxing to 0.008mm rms aft of the nosetip). More recent results 3,10 indicated that larger values would have been acceptable, however the more restrictive roughness limits were employed for the payload design to provide a generous factor of safety for the experiment. A discrete roughness trip was installed on one side of the payload with the aim of extracting

Optimization methods have been widely applied to the aerodynamic design of gas turbine blades. While applying optimization to high-fidelity computational fluid dynamics (CFD) simulations has proven capable of improving engineering design performance, a challenge has been overcoming the prolonged run-time due to the computationally expensive CFD runs. Reduced-order models and, more recently, machine learning methods have been increasingly used in gas turbine studies to predict performance metrics and operational characteristics, model turbulence, and optimize designs. The application of machine learning methods allows for utilizing existing knowledge and datasets from different sources, such as previous experiments, CFD, low-fidelity simulations, 1D or system-level studies. The present study investigates inserting a machine learning model that utilizes such data into a high-fidelity CFD driven optimization process, and hence effectively reduces the number of required evaluations of the CFD model. Artificial Neural Network (ANN) models were trained on data from over three thousand two-dimensional (2D) CFD analyses of turbine blade cross-sections. The trained ANN models were then used as surrogates in a nested optimization process alongside a full three-dimensional Navier–Stokes CFD simulation. The much lower evaluation cost of the ANN model allows for tens of thousands of design evaluations to guide the search of the best blade profiles to be used in the more expensive, high-fidelity CFD runs, improving the progress of the optimization while reducing the required computation time. It is estimated that the current workflow achieves a five-fold reduction in computational time in comparison to an optimization process that is based on three-dimensional (3D) CFD simulations alone. The methodology is demonstrated on the NASA/General Electric Energy Efficient Engine (E3) high pressure turbine blade and found Pareto front designs with improved blade efficiency and power over the baseline. Quantitative analysis of the optimization data reveals that some design parameters in the present study are more influential than others, such as the lean angle and tip scaling factor. Examining the optimized designs also provides insight into the physics, showing that the optimized designs have a lower amount of pressure drop near the trailing edge, but have an earlier onset of pressure drop on the suction side surface when compared to the baseline design, contributing to the observed improvements in efficiency and power.

The article is directly related to the authors’ previous study of the remotely operated underwater vehicle’s (ROV) motion, where the mathematical model of the ROV motion is derived for laminar flow of water. This solution of the ROV motion has been improved by using the three-dimensional computational fluid dynamics (CFD) simulation that allows simulating the turbulent flow, which is mainly generated by propellers. Both methods were coupled to obtain more accurate values of hydrodynamic damping coefficients for the improved determination of the ROV motion velocity. Results of the solution are discussed and some of them are compared with the experiment.

One of the major barriers for polymer electrolyte membrane (PEM) fuel cells to be commercially viable for stationary and transport applications is the durability of membranes undergoing chemical and mechanical degradation over the period of operation. Toward understanding the effects of operating parameters on membrane durability, this paper presents numerical simulations for a single channel PEM fuel cell undergoing changes in load, by subjecting the unit cell to step change in voltage. The objective is to elucidate the mechanical response of membrane, which is subjected to hygral (water) loading and unloading cycles at constant temperature. Detailed three-dimensional (3D) computational fluid dynamics (CFD) simulations are conducted, taking in to account the complex interactions of water transport dynamics and load changes, to accurately capture the water content in the membrane with changes in cell voltage. The water content obtained through CFD simulations is, in turn, used to carry out two-dimensional (2D) finite element (FE) analysis to predict the mechanical response of the membrane undergoing cyclic change in water content, as the operating voltage is cycled. The effects of cyclic changes in cell potential on the stresses induced, amount of plastic strain and their localization are analyzed for various inlet cathode humidity values for two sections along the length of the fuel cell.

Coal use for generation of electricity is used extensively world-wide accounting for 40% of total power generation. Even with reductions in use over the last 10 years, coal still accounts for 20% of total electrical generation in the United States. An often-overlooked aspect of Pulverized Coal (PC) combustion is the erosion and abrasion of the coal injection nozzles. Currently there are over 300 active PC boilers in the US and over 1000 worldwide, with each boiler having 20–40 high alloy cast injectors. Due to the high velocity of PC injection and associated elevated rates of metal loss, these nozzles require constant replacement. Replacement and costs associated with loss of revenue, required scaffolding and casting can be a significant part of Operation and Maintenance (O&M) of a PC boiler. In addition to the constant requirement for thousands of replacement injection nozzles every year, combustion performance, NOx reduction, carbon conversion and general boiler efficiency will be impacted by hardware that is out of specification, if not replaced in a “timely” manner. Significant research in the 1980’s [1] provided some insight into the loss-of-metal process during PC injection, but limitations of existing hardware and software prevented more than an empirical methodology to be developed. In parallel with the literature work and research specifically for PC coal erosion rates, generalized efforts were employed and reported [6–9]. Meng [4] summarized model development for solid particles transported by a liquid or gas as highly empirical with little commonality between the models developed by the various researchers. Meng also made specific recommendations for less empiricism in model development methodology. Although there are several state-of-the-art empirical models [6, 8 & 9] more recently, semi-mechanistic models have been developed to predict solid particle erosion (e.g. Arabnejad et al., [17]) and have been successfully applied to sand erosion and abrasion in pipelines. In the current study, this method is being applied to PC injection nozzles coupled to detailed computational fluid dynamics (CFD) simulations. The intent is to quantify nozzle material loss rates, due to impacting coal particles, as a function of geometry, local velocities, and coal properties. The method used is utilizing CFD to model flow of particles and their impingement velocity with the PC nozzles. Then erosion models that are a function of impingement speed, angle, frequency and materials properties to examine erosion rates. The insight gained from the modeling will allow improved nozzle design, increased duty life, more cost-effective supply, and elevated injection velocity. In particular, low NOx coal combustion can be critically dependent on utilization of elevated injection velocities, which previous empirical models discourage. This paper reports on the application of the erosion equations and methods developed at the Erosion/Corrosion Research Center of The University of Tulsa for predicting solid particle erosion of a PC injection nozzle that shows details of erosion patterns and parameters that are responsible for elevated erosion tendencies in the field. RJM-International is familiar with the nozzle from various applications that are associated with Low NOx operation. The advantages of utilizing semi-mechanistic erosion equations and models coupled with CFD simulations as compared to previous empirical methods are discussed. Shortcomings of applying the existing coal erosion model is also reported along with “next steps” required to successfully apply the method to PC injection nozzle designs for much higher combustion efficiencies than existing ones.

Rationale: We previously found oropharyngeal enlargement and subglottal narrowing in asthma and chronic obstructive pulmonary disease (COPD) patients compared to healthy individuals. This study aimed to investigate the impact of oropharyngeal remodeling on the upper airway airflow dynamics in association with lung structure-function impairment in obstructive lung disease (OLD). Methods: Upper airway computed tomography (CT) scans, inspiratory (total lung capacity) and expiratory (functional residual capacity) lung CTs, and clinical data were collected from 185 participants (26 healthy, 56.6±5.1y; 73 COPD, 71.1±7.5y, and 86 asthma, 64.8±12.5y) enrolled in Jeonbuk National University Hospital, Jeonju, Korea. We conducted quantitative inspiratory-expiratory CT analysis and one-dimensional (1D) computational fluid dynamics (CFD) simulations of airflow in the lower airways, for all participants. Then, we selected ten representative subjects in each group based on key features of upper airways (healthy: 56±6.2y; COPD: 69.7±7.4y; asthma: 63.2±6.3y) and conducted three-dimensional (3D) CFD simulations of breathing (tidal volume: 6 ml/kg). Results: Patients with OLD showed 11 times greater CFD-derived lower airway resistance and 3.8% smaller transpulmonary pressure than healthy controls. 3D CFD simulations showed less pressure drop from the mouth to the level of the sixth cervical vertebra (C6) during inhalation in OLD (COPD: 37.3±41.9Pa; asthma: 32.01±18.4 Pa) than in healthy subjects (70.7±48.5) Pa. Upper (oropharyngeal) airway resistance was also smaller in OLD (COPD: 155.0±188.0 kPa·s/m³; asthma: 116.2±61.5 kPa·s/m³) than in healthy subjects (229.4±142.2 kPa·s/m³). This is attributable to oropharyngeal enlargement measured by greater oral space air fraction and larger supraglottal airway diameter at the level of the fourth cervical vertebra (C4). Less upper airway pressure drop to the level of C6 correlated with upper airway enlargement measured by normalized upper airway air volume (r=-0.60, p<0.001) and diameter at C4 (r=-0.56, p=0.001) as well as lung structure-function impairment such as functional small airways disease percent (fSAD%), less volumetric deformation (J), and less relative displacement (s[asterisk]) (r=-0.40, 0.47, 0.54; p=0.030, 0.009, 0.002) and worse spirometry outcomes such as post-BD FEV1% (r=0.54, p=0.002) and FEV1/FVC (r=0.54, p=0.002). Conclusion: CT-based CFD simulations showed patients with obstructive lung disease experienced elevated airway resistance in the lower airways but reduced pressure drop and airway resistance due to oropharyngeal enlargement during inhalation. Reduced aerodynamic effort may help compensate excessive respiratory effort required in the lower airways. Findings suggest that upper airway imaging and airflow analysis allows more complete interpretation of the entire respiratory function altered with airflow obstruction.

Computational fluid dynamic (CFD) simulations in support of the SHARP-B2 (Slender Hypervelocity Aerothermodynamic Research Probes) program are presented. Pre-flight simulations of the aerothermal flight environment have been made to aid in the design of the flight hardware and instrumentation. Simulations of a critical flight qualification ground test performed in the 20 MW Panel Test Facility (PTF) arc jet, which is equipped with a semi-elliptical nozzle, have also been performed. The arc jet simulations were performed with the same CFD code that is used in the flight calculations. For both the flight and the arc jet simulations, the CFD results are used to provide surface heat transfer coefficients that serve as boundary conditions for an in-depth conduction thermal response code. By using the same CFD tool to compute the aerothermal environments for both the ground test and the flight test environment, useful comparisons are made regarding the traceability of the ground test environment to flight. Introduction The NASA Ames Research Center has been developing new Ultra High Temperature Ceramics (UHTC's) with the goal that these materials will enable sharp leading edges to be used for future space vehicles. Because of their unique thermo-structural properties, these materials are capable of operation at temperatures near 5100 °F without ablation. The materials have been developed and tested in ground-based arc jet facilities, and a flight test program designated SHARP (Slender Hypervelocity Aerothermodynamic Research Probes) has been initiated. The first flight demonstration, SHARP-B1, incorporated a UHTC nosetip mounted on a U.S. Air Force Mkl2A entry vehicle in collaboration with Sandia National Laboratory (SNL), and was successfully flown in May, 1997. The second flight test, SHARP-B2, which incorporated four instrumented UHTC strakes mounted on the side of the entry vehicle, was flown in September 2000. The goal of these flight tests is to assess the performance of the materials under entry conditions. The use of Computational Fluid Dynamic (CFD) simulations for the design of Thermal Protection Systems (TPS) has evolved to an extent that they have been integrated into the preliminary design process of Reusable Launch Vehicle (RLV) programs such as the X-33. Real-gas CFD simulations with finite-rate chemistry and proper boundary conditions for coupling with material thermal response codes are now routinely performed on high-end laboratory workstations. Much of the ground based testing of advanced TPS components is done in arc-heated test facilities such as those located in the Arc Jet Complex at the NASA Ames Research Center. These facilities are capable of simulating the high enthalpy flow environment experienced by entry vehicles for a broad range of test conditions and configurations. Semi-elliptical nozzles are available for the testing of flat panels in a high enthalpy boundary layer environment. CFD is • Aerospace Engineer, Reacting Flow Environments Branch, Member AIAA. t Senior Research Scientist, ELORET, Member AIAA. Copyright © 2001 by the American Institute of Aeronautics and Astronautics, Inc. No copyright is asserted in the United States under Title 17, U.S. Code. The U.S. Government has a royalty-free license to exercise all rights under the copyright claimed herein for Governmental Purposes. All other rights are reserved by the copyright owner. (c)2001 American Institute of Aeronautics & Astronautics or Published with Permission of Author(s) and/or Author(s)' Sponsoring Organization.

In industrial environments, boiler units are widely used to supply heat and electrical power. At an integrated steel mill, industrial boilers combust a variable mixture of metallurgical gases combined with additional fuels to generate high-pressure superheated steam. Most tangentially fired boilers have experienced water wall tube failures in the combustion zone, which are thought to be caused by some deficiency in the combustion process. The challenge faced in this present process is that there are very limited means to observe the boiler operation. In this study, a three-dimensional Computational Fluid Dynamics (CFD) modeling and simulation of an industrial tangentially fired boiler firing metallurgical gases was conducted. Simulation results obtained from the assembled CFD model were validated by industrial experiments. A quick comparison of the flame shape from the simulation to the actual flame in the boiler showed a good agreement. The flow field and temperature distribution inside the tangentially fired boiler were analyzed under the operation conditions, and a wall water tube overheating problem was observed and directly related to the flow characteristics.

Investigation on the drainage condition within the ballast layer based on 3D CFD simulations

CFD simulations of the wind environment around an airport terminal building

CFD simulation and experimental validation of a GM type double inlet pulse tube refrigerator

High pressure ratio, radial-inflow turbines typically experience supersonic expansion in the nozzle section. Accurate estimation of the flow conditions and velocity triangle at the nozzle outlet is of critical importance in correctly predicting the overall turbine performance. The meanline modeling of such a nozzle requires special attention, due to the significantly altered flow field downstream of the throat. In this study, the flow field of a supersonic expansion nozzle is investigated, using a three-dimensional (3D) computational fluid dynamics (CFD) simulation calibrated with test data. Three different CFD configurations are explored: the nozzle alone, the nozzle plus rotor coupled with a mixing plane, and the nozzle plus rotor coupled with the nonlinear harmonic (NLH) method. These configurations are compared to each other to gauge the effect of the rotor and stator interaction and the potential for error in establishing the velocity triangles. The exit vane angle, number of vanes, and expansion ratio across the nozzle are systematically varied to provide the data as the base for nozzle modeling. Finally, a meanline method is proposed to calculate the pressure loss and flow deviation at the nozzle outlet and is compared with CFD results.

Effect of biofouling roughness on a marine propeller's performance including cavitation and underwater radiated noise (URN)

본 연구에서는 역전기투석 장치 내 스페이서(spacer)에 의한 유동변화와 스페이서의 높이변화에 따른 해수의 유동 및 이온전달 영향에 관한 연구를 수행하였다. 육각형 모양의 스페이서에 대해 3차원 전산유체해석을 진행하였다. 모델링을 수행한 결과, 레이놀즈수(Reynolds number)가 커짐에 따라 스월량(swirl)이 커지며 단위시간당 해수의 이온이 멤브레인(membrane)으로 전달되는 양이 늘어나지만, 반면에 입출구의 압력차도 증가하였다. 또한 스페이서가 두꺼울수록 파워수(Power number)와 셔우드수(Sherwood number)가 증가하였다. In this study, the effects of spacer and variation of spacer height in reverse electrodialysis (RED) on the seawater and ion transport were investigated. A three-dimensional computational fluid dynamics (CFD) simulation for a hexagonal spacer was constructed. The results showed that the swirl in the channel and ion transport rate to the membrane were enhanced at higher Reynolds number, on the other hand, pressure difference between the inlet and outlet was increased. Moreover thicker spacer increased Power number and Sherwood number.

This paper studies the injection of gas in a stagnant solid bed via a horizontal nozzle from experimental and theoretical perspectives, with the analysis of permanent jet plumes and subsequent bubble detachment. Advanced 3D X-Ray imaging techniques have been developed and used to observe the phenomenon, as well as to quantify important process parameters (gas distribution, jet length, bubble size, etc.). The experimental results are compared with those obtained from three-dimensional computational fluid dynamics (CFD) simulations of a gas-solid fluidized bed with primary air injection performed through a two-orifice horizontal nozzle. The proposed model correctly predicts the jet penetration at all the jet velocities tested. Uneven distribution of air through the cross-section of the bed is also observed, with the presence of the same two distinct regions experimentally observed, namely a fluidized core region and a compacted peripheral region. However, the model fails in predicting jets interaction and curvature due to asynchronous bubble detachment from the jets. This study demonstrates the usefulness of X-ray radiography in noninvasively visualising detailed internal features of industrial fluidized beds, thus providing an excellent benchmark to challenge the assumptions made in computational and theoretical models.