Pub Date : 2023-08-20DOI: 10.3390/aerospace10080727
Tomasz Palacz, J. Cieślik
The paper is part of the research aimed at determining if the vortex flow pancake (VFP) hybrid rocket engine is feasible as green in-space chemical propulsion. The objective of this study is to test an N2O/HDPE VFP hybrid ignited with N2O/C3H8 torch igniter. The N2O is used in self-pressurizing mode, which results in two-phase flow and varying inlet conditions, thus better simulating real in-space behavior. The study begins with characterizing the torch igniter, followed by hot-fire ignition tests of the VFP. The results allow for the improved design of the torch igniter and VFP hybrid. The axial regression rate ballistic coefficients are reported for the N2O/HDPE propellants in the VFP configuration.
{"title":"Testing of the N2O/HDPE Vortex Flow Pancake Hybrid Rocket Engine with Augmented Spark Igniter","authors":"Tomasz Palacz, J. Cieślik","doi":"10.3390/aerospace10080727","DOIUrl":"https://doi.org/10.3390/aerospace10080727","url":null,"abstract":"The paper is part of the research aimed at determining if the vortex flow pancake (VFP) hybrid rocket engine is feasible as green in-space chemical propulsion. The objective of this study is to test an N2O/HDPE VFP hybrid ignited with N2O/C3H8 torch igniter. The N2O is used in self-pressurizing mode, which results in two-phase flow and varying inlet conditions, thus better simulating real in-space behavior. The study begins with characterizing the torch igniter, followed by hot-fire ignition tests of the VFP. The results allow for the improved design of the torch igniter and VFP hybrid. The axial regression rate ballistic coefficients are reported for the N2O/HDPE propellants in the VFP configuration.","PeriodicalId":50845,"journal":{"name":"Aerospace America","volume":"34 1","pages":""},"PeriodicalIF":0.1,"publicationDate":"2023-08-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"79029809","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-08-20DOI: 10.3390/aerospace10080731
Lars M. Heijenrath, W. Verhagen
Accurate estimation of spare part demand is challenging in the case of intermittent or lumpy demand, characterised by infrequent demand occurrence and variability in demand size. While prior research has considered the effect of exogenous variables on spare part demand, there is a lack of research considering the effects of repair quality and aggregated spare part demand behaviour across fleets of assets under the influence of multiple simultaneously acting drivers of failure. This research provides new insights towards the problem of estimating variable spare part demand through modelling and simulation of the effects of multiple, simultaneously considered spare part demand drivers. In particular, a contribution to the state of the art is introduced by the use of a Branching Poisson Process (BPP) to model repair quality effects for spare part demand generation in conjunction with several demand drivers. The approach is applied in a numerical study which involves component failure characteristics based on real-life data from an aircraft maintenance, repair and overhaul (MRO) provider. It is shown that repair quality improvements drive down the variance in the demand and the total number of failures over time, and outperform the effect of environmental drivers of failure in terms of demand generation.
{"title":"The Influence of Repair Quality on Aircraft Spare Part Demand Variability","authors":"Lars M. Heijenrath, W. Verhagen","doi":"10.3390/aerospace10080731","DOIUrl":"https://doi.org/10.3390/aerospace10080731","url":null,"abstract":"Accurate estimation of spare part demand is challenging in the case of intermittent or lumpy demand, characterised by infrequent demand occurrence and variability in demand size. While prior research has considered the effect of exogenous variables on spare part demand, there is a lack of research considering the effects of repair quality and aggregated spare part demand behaviour across fleets of assets under the influence of multiple simultaneously acting drivers of failure. This research provides new insights towards the problem of estimating variable spare part demand through modelling and simulation of the effects of multiple, simultaneously considered spare part demand drivers. In particular, a contribution to the state of the art is introduced by the use of a Branching Poisson Process (BPP) to model repair quality effects for spare part demand generation in conjunction with several demand drivers. The approach is applied in a numerical study which involves component failure characteristics based on real-life data from an aircraft maintenance, repair and overhaul (MRO) provider. It is shown that repair quality improvements drive down the variance in the demand and the total number of failures over time, and outperform the effect of environmental drivers of failure in terms of demand generation.","PeriodicalId":50845,"journal":{"name":"Aerospace America","volume":"35 1","pages":""},"PeriodicalIF":0.1,"publicationDate":"2023-08-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"89926614","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-08-20DOI: 10.3390/aerospace10080729
Mengge Wang, Ziyun Wang, Yue Zhang, Daishu Cheng, H. Tan, Kun Wang, Simin Gao
A shock wave/boundary layer interaction (SWBLI) is a common phenomenon in supersonic inlet flow, which can significantly degrade the aerodynamic performance of the inlet by inducing boundary layer separation. To address this issue, in this paper, we propose the use of a dynamic vortex generator to control the SWBLI in a typical supersonic inlet. The unsteady simulation method based on dynamic grid technology was employed to verify the effectiveness of the proposed method of control and investigate its mechanism. The results showed that, in a duct of finite width at the inlet, the SWBLI generated complex three-dimensional (3D) flow structures with remarkable swirling properties. At the same time, vortex pairs were generated close to the side wall as a result of its presence, and this led to the intensification of transverse flow and, in turn, the formation of a complex 3D structure of the flow of the separation bubble. The dynamic vortex generator induced oscillations of variable intensity in the vortex system in the supersonic boundary layer that enhanced the mixing between the boundary layer flow and the mainstream. Meanwhile, the unique effects of “extrusion” and “suction” in the oscillation process continued to charge the airflow, and the distribution of velocity in the boundary layer significantly improved. As the oscillation frequency of the vortex generator increased, its charging effect on low-velocity flow in the boundary layer increased, and its control effect on the flow field of the SWBLI became more pronounced. The proposed method of control reduced the length of the separation bubble by 31.76% and increased the total pressure recovery coefficient at the inlet by 6.4% compared to the values in the absence of control.
{"title":"Control of Cowl Shock/Boundary Layer Interaction in Supersonic Inlet Based on Dynamic Vortex Generator","authors":"Mengge Wang, Ziyun Wang, Yue Zhang, Daishu Cheng, H. Tan, Kun Wang, Simin Gao","doi":"10.3390/aerospace10080729","DOIUrl":"https://doi.org/10.3390/aerospace10080729","url":null,"abstract":"A shock wave/boundary layer interaction (SWBLI) is a common phenomenon in supersonic inlet flow, which can significantly degrade the aerodynamic performance of the inlet by inducing boundary layer separation. To address this issue, in this paper, we propose the use of a dynamic vortex generator to control the SWBLI in a typical supersonic inlet. The unsteady simulation method based on dynamic grid technology was employed to verify the effectiveness of the proposed method of control and investigate its mechanism. The results showed that, in a duct of finite width at the inlet, the SWBLI generated complex three-dimensional (3D) flow structures with remarkable swirling properties. At the same time, vortex pairs were generated close to the side wall as a result of its presence, and this led to the intensification of transverse flow and, in turn, the formation of a complex 3D structure of the flow of the separation bubble. The dynamic vortex generator induced oscillations of variable intensity in the vortex system in the supersonic boundary layer that enhanced the mixing between the boundary layer flow and the mainstream. Meanwhile, the unique effects of “extrusion” and “suction” in the oscillation process continued to charge the airflow, and the distribution of velocity in the boundary layer significantly improved. As the oscillation frequency of the vortex generator increased, its charging effect on low-velocity flow in the boundary layer increased, and its control effect on the flow field of the SWBLI became more pronounced. The proposed method of control reduced the length of the separation bubble by 31.76% and increased the total pressure recovery coefficient at the inlet by 6.4% compared to the values in the absence of control.","PeriodicalId":50845,"journal":{"name":"Aerospace America","volume":"49 1","pages":""},"PeriodicalIF":0.1,"publicationDate":"2023-08-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"84083352","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-08-20DOI: 10.3390/aerospace10080730
Qidong Zhang, G. Lin, Jinghui Guo, Haichuan Jin, Qiming Zhang
The thermal management system (TMS) for aircraft fuel is a critical component of integrated TMSs in aircraft. As such, its optimal design is necessary to ensure the efficient completion of flight missions. This study presents the model building of a numerical simulation model for the fuel TMS, with the objective of minimizing fuel return flow. Sensitivity analysis was performed using variance analysis. The genetic algorithm was utilized for the optimization of the model building, taking into consideration the system’s geometric structure and performance parameters, which include the pipe length, the ram air-fuel HX’s efficiency, and the ram air’s volume flow rate in the ram air cooling subsystem, as design variables. The optimization solution for system design variables yielded a design scheme with the highest working efficiency for the fuel TMS. In this paper, the genetic algorithm in AMEsim software is adopted, which can also effectively optimize the design parameters and achieve the optimization objective. Compared with the original TMS structure, the heat dissipation capacity of the fuel TMS is improved and reduced the return fuel flow by 67.4% after the optimization of system structure parameters.
{"title":"Optimization Research on the Heat Transfer Capacity of an Aircraft Fuel Thermal Management System","authors":"Qidong Zhang, G. Lin, Jinghui Guo, Haichuan Jin, Qiming Zhang","doi":"10.3390/aerospace10080730","DOIUrl":"https://doi.org/10.3390/aerospace10080730","url":null,"abstract":"The thermal management system (TMS) for aircraft fuel is a critical component of integrated TMSs in aircraft. As such, its optimal design is necessary to ensure the efficient completion of flight missions. This study presents the model building of a numerical simulation model for the fuel TMS, with the objective of minimizing fuel return flow. Sensitivity analysis was performed using variance analysis. The genetic algorithm was utilized for the optimization of the model building, taking into consideration the system’s geometric structure and performance parameters, which include the pipe length, the ram air-fuel HX’s efficiency, and the ram air’s volume flow rate in the ram air cooling subsystem, as design variables. The optimization solution for system design variables yielded a design scheme with the highest working efficiency for the fuel TMS. In this paper, the genetic algorithm in AMEsim software is adopted, which can also effectively optimize the design parameters and achieve the optimization objective. Compared with the original TMS structure, the heat dissipation capacity of the fuel TMS is improved and reduced the return fuel flow by 67.4% after the optimization of system structure parameters.","PeriodicalId":50845,"journal":{"name":"Aerospace America","volume":"1277 1","pages":""},"PeriodicalIF":0.1,"publicationDate":"2023-08-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"86483100","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-08-20DOI: 10.3390/aerospace10080733
Rhys Jones, D. Peng, Andrew Ang, Richard W. Aston, Nicole D. Schoenborn, N. Phan
This paper first presents the results of an experimental study into the damage tolerance of AA7075-T6, which is widely used in both fixed- and rotary-wing aircraft, space structures, and laser bed powder fusion (LBPF) Scalmalloy specimens built by Boeing Space, Intelligence, and Weapons Systems. To this end, four single edge notch AA7075-T6 specimens and four identical single edge notch LBPF Scalmalloy specimens were tested. The resultant crack growth curves reveal that Boeing Space, Intelligence, and Weapons Systems AM-built Scalmalloy is more damage tolerant than conventionally built AA7075-T6. This finding leads to the observation that the da/dN versus ΔK curves associated with Scalmalloy and conventionally manufactured AA2024-T3 are similar. These findings highlight the potential for Boeing Space, Intelligence, and Weapons Systems AM-built Scalmalloy to be used to extend the operational lives of military aircraft by the on-demand printing of limited-life Scalmalloy replacement parts.
{"title":"A Comparison of the Damage Tolerance of AA7075-T6, AA2024-T3, and Boeing Space, Intelligence, and Weapons Systems AM-Built LPBF Scalmalloy","authors":"Rhys Jones, D. Peng, Andrew Ang, Richard W. Aston, Nicole D. Schoenborn, N. Phan","doi":"10.3390/aerospace10080733","DOIUrl":"https://doi.org/10.3390/aerospace10080733","url":null,"abstract":"This paper first presents the results of an experimental study into the damage tolerance of AA7075-T6, which is widely used in both fixed- and rotary-wing aircraft, space structures, and laser bed powder fusion (LBPF) Scalmalloy specimens built by Boeing Space, Intelligence, and Weapons Systems. To this end, four single edge notch AA7075-T6 specimens and four identical single edge notch LBPF Scalmalloy specimens were tested. The resultant crack growth curves reveal that Boeing Space, Intelligence, and Weapons Systems AM-built Scalmalloy is more damage tolerant than conventionally built AA7075-T6. This finding leads to the observation that the da/dN versus ΔK curves associated with Scalmalloy and conventionally manufactured AA2024-T3 are similar. These findings highlight the potential for Boeing Space, Intelligence, and Weapons Systems AM-built Scalmalloy to be used to extend the operational lives of military aircraft by the on-demand printing of limited-life Scalmalloy replacement parts.","PeriodicalId":50845,"journal":{"name":"Aerospace America","volume":"48 1","pages":""},"PeriodicalIF":0.1,"publicationDate":"2023-08-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"75861694","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-08-20DOI: 10.3390/aerospace10080726
A. Alexiou, Ioannis Kolias, N. Aretakis, K. Mathioudakis
An approach for preliminary aero-engine design, incorporating a mean-line code for the design of axial-flow, multi-stage compressors, is presented. The compressor mean-line code is developed and integrated within a framework for the preliminary design and assessment of aero-engine concepts. It is then combined with modules for compressor map generation, multi-point engine design, steady-state and transient engine off-design performance and aircraft mission analysis. Implementation examples are presented, demonstrating the determination of the optimal combination of compressor and engine design parameters for achieving minimum fuel burn over a specific aircraft mission, while obeying constraints that guarantee operability over the entire flight envelope. Constraints related to compressor stability during transient maneuvers between idle and static take-off conditions and engine temperature limits at maximum take-off are respected by the final design. The results demonstrate the potential for design trade-offs between engine performance at the aircraft mission level and compressor aerodynamic stability.
{"title":"Aero-Engine Preliminary Design Optimization and Operability Studies Supported by a Compressor Mean-Line Design Module","authors":"A. Alexiou, Ioannis Kolias, N. Aretakis, K. Mathioudakis","doi":"10.3390/aerospace10080726","DOIUrl":"https://doi.org/10.3390/aerospace10080726","url":null,"abstract":"An approach for preliminary aero-engine design, incorporating a mean-line code for the design of axial-flow, multi-stage compressors, is presented. The compressor mean-line code is developed and integrated within a framework for the preliminary design and assessment of aero-engine concepts. It is then combined with modules for compressor map generation, multi-point engine design, steady-state and transient engine off-design performance and aircraft mission analysis. Implementation examples are presented, demonstrating the determination of the optimal combination of compressor and engine design parameters for achieving minimum fuel burn over a specific aircraft mission, while obeying constraints that guarantee operability over the entire flight envelope. Constraints related to compressor stability during transient maneuvers between idle and static take-off conditions and engine temperature limits at maximum take-off are respected by the final design. The results demonstrate the potential for design trade-offs between engine performance at the aircraft mission level and compressor aerodynamic stability.","PeriodicalId":50845,"journal":{"name":"Aerospace America","volume":"65 1","pages":""},"PeriodicalIF":0.1,"publicationDate":"2023-08-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"74102096","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-08-19DOI: 10.3390/aerospace10080725
Yanan Wu, H. Xuan, Changyao Wu, D. Mi, Mingmin Qu, Tao Jin
Underplatform dampers (UPDs), a type of dry friction damper, are commonly used for vibration reduction of turbine blades. This study investigated the effect of UPDs on the forced torsional vibration response of turbine blades within a multi-blade system. Pre-stressed finite element modal analysis and the harmonic balance method were combined to calculate the forced torsional vibration responses of a system with and without UPDs. The experiments were then carried out on a rotating multi-blade system with and without UPDs, with a focus on the effect of mass stacking on damping performance. The results showed that the installation of underplatform dampers could increase the frequency corresponding to the maximum response of the blade torsional vibration and cause multiple peaks that varied in the vibration response based on the mass of the UPDs. With an appropriate normal force, the underplatform dampers could effectively reduce the blade torsional vibration by 68.9%. However, excessive normal force of UPDs could lead to multiple large vibration peaks, which should be avoided in engineering practice. Additionally, the numerical results for the forced torsional vibration response of the rotating multi-blade system with UPDs were relatively close to the experimental results, indicating that the calculation method could be effectively applied to the nonlinear prediction of forced vibrations of rotating blades with dampers.
{"title":"Study on the Forced Torsional Vibration Response of Multiple Rotating Blades with Underplatform Dampers","authors":"Yanan Wu, H. Xuan, Changyao Wu, D. Mi, Mingmin Qu, Tao Jin","doi":"10.3390/aerospace10080725","DOIUrl":"https://doi.org/10.3390/aerospace10080725","url":null,"abstract":"Underplatform dampers (UPDs), a type of dry friction damper, are commonly used for vibration reduction of turbine blades. This study investigated the effect of UPDs on the forced torsional vibration response of turbine blades within a multi-blade system. Pre-stressed finite element modal analysis and the harmonic balance method were combined to calculate the forced torsional vibration responses of a system with and without UPDs. The experiments were then carried out on a rotating multi-blade system with and without UPDs, with a focus on the effect of mass stacking on damping performance. The results showed that the installation of underplatform dampers could increase the frequency corresponding to the maximum response of the blade torsional vibration and cause multiple peaks that varied in the vibration response based on the mass of the UPDs. With an appropriate normal force, the underplatform dampers could effectively reduce the blade torsional vibration by 68.9%. However, excessive normal force of UPDs could lead to multiple large vibration peaks, which should be avoided in engineering practice. Additionally, the numerical results for the forced torsional vibration response of the rotating multi-blade system with UPDs were relatively close to the experimental results, indicating that the calculation method could be effectively applied to the nonlinear prediction of forced vibrations of rotating blades with dampers.","PeriodicalId":50845,"journal":{"name":"Aerospace America","volume":"362 1","pages":""},"PeriodicalIF":0.1,"publicationDate":"2023-08-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"75502464","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-08-18DOI: 10.3390/aerospace10080723
Natsuki Tsushima, Russell Higuchi, Koji Yamamoto
By deliberately designing microscopic internal mechanisms, architected materials can achieve a variety of material properties without changing constituent materials. Integration of the architected materials into a structure as substructures has a good potential to enhance structural performance and realize wide design freedom. This paper explores the capabilities of multiscale approaches for lattice structures, which is a major mechanism in architected materials. The objectives of this paper are (1) to demonstrate the capabilities of the framework to evaluate stiffness characteristics of lattice structures with two different two-scale analysis approaches and (2) to assess the accuracies and validity ranges of both approaches for appropriate evaluations of lattice structures. The two-scale analysis framework consists of the computational homogenizations for the generalized stiffness (ABD) and 3D stiffness (C) matrices. Equivalent stiffness characteristics of the unit cell are obtained by computational homogenizations to effectively capture the macroscopic responses of lattice structures. This study provides a comprehensive correlation study between the prediction accuracies of the two-scale analysis approaches in terms of tensile, bending, and torsional stiffness characteristics for practical modeling and development of lattice structures. The study will contribute a guideline for effective designs of high-performance structures with architected materials.
{"title":"Correlation Studies of Different Decoupled Two-Scale Simulations for Lattice Structures","authors":"Natsuki Tsushima, Russell Higuchi, Koji Yamamoto","doi":"10.3390/aerospace10080723","DOIUrl":"https://doi.org/10.3390/aerospace10080723","url":null,"abstract":"By deliberately designing microscopic internal mechanisms, architected materials can achieve a variety of material properties without changing constituent materials. Integration of the architected materials into a structure as substructures has a good potential to enhance structural performance and realize wide design freedom. This paper explores the capabilities of multiscale approaches for lattice structures, which is a major mechanism in architected materials. The objectives of this paper are (1) to demonstrate the capabilities of the framework to evaluate stiffness characteristics of lattice structures with two different two-scale analysis approaches and (2) to assess the accuracies and validity ranges of both approaches for appropriate evaluations of lattice structures. The two-scale analysis framework consists of the computational homogenizations for the generalized stiffness (ABD) and 3D stiffness (C) matrices. Equivalent stiffness characteristics of the unit cell are obtained by computational homogenizations to effectively capture the macroscopic responses of lattice structures. This study provides a comprehensive correlation study between the prediction accuracies of the two-scale analysis approaches in terms of tensile, bending, and torsional stiffness characteristics for practical modeling and development of lattice structures. The study will contribute a guideline for effective designs of high-performance structures with architected materials.","PeriodicalId":50845,"journal":{"name":"Aerospace America","volume":"85 1","pages":""},"PeriodicalIF":0.1,"publicationDate":"2023-08-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"77164595","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-08-18DOI: 10.3390/aerospace10080724
Q. Kong, W. Jia
To investigate the aerodynamic characteristics of the fan in windmilling conditions, a new body force model with the fan rotational speed prediction model was developed. The fan rotational speed prediction model was built based on the balance of fan output torque and resistance torque. The rotational speed of the fan spool can be iteratively solved simultaneously with solving the governing equations without requiring mass flow rate or other inputs. The comparison with the experimental results shows that using the body force model can accurately predict the rotational speed of the fan spool under different operating conditions. The radial distribution of flow parameters can be obtained. Moreover, numerical simulations of the fan under different circumferential total pressure distortion inflow conditions were conducted using the body force model. The results show that, unlike the design point and non-design point at which the fan operates normally, the high radius region of the fan is in the “turbine mode” while the low radius region is in the “compressor mode” under windmilling conditions. The different effects on the longitudinal vortex in the two regions deepen and alleviate the circumferential distortion, respectively. There are strong circumferential and radial pressure gradients at the junction of the distortion-affected zone and the non-distortion-affected zone, adding additional mixing losses.
{"title":"A Three-Dimensional Body Force Modeling of Fans in Windmilling Condition and Its Application","authors":"Q. Kong, W. Jia","doi":"10.3390/aerospace10080724","DOIUrl":"https://doi.org/10.3390/aerospace10080724","url":null,"abstract":"To investigate the aerodynamic characteristics of the fan in windmilling conditions, a new body force model with the fan rotational speed prediction model was developed. The fan rotational speed prediction model was built based on the balance of fan output torque and resistance torque. The rotational speed of the fan spool can be iteratively solved simultaneously with solving the governing equations without requiring mass flow rate or other inputs. The comparison with the experimental results shows that using the body force model can accurately predict the rotational speed of the fan spool under different operating conditions. The radial distribution of flow parameters can be obtained. Moreover, numerical simulations of the fan under different circumferential total pressure distortion inflow conditions were conducted using the body force model. The results show that, unlike the design point and non-design point at which the fan operates normally, the high radius region of the fan is in the “turbine mode” while the low radius region is in the “compressor mode” under windmilling conditions. The different effects on the longitudinal vortex in the two regions deepen and alleviate the circumferential distortion, respectively. There are strong circumferential and radial pressure gradients at the junction of the distortion-affected zone and the non-distortion-affected zone, adding additional mixing losses.","PeriodicalId":50845,"journal":{"name":"Aerospace America","volume":"122 1","pages":""},"PeriodicalIF":0.1,"publicationDate":"2023-08-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"80982977","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-08-17DOI: 10.3390/aerospace10080720
Spyridon Antoniou, S. Kapsalis, P. Panagiotou, K. Yakinthos
The current study investigated the effect of leading-edge slats on the longitudinal stability at high angles of attack of a Blended-Wing-Body (BWB) Unmanned Air Vehicle (UAV). Using a Design of Experiments (DOE) approach and, specifically, the Taguchi method, four leading-edge slat design parameters were investigated on three different levels. These parameters were the slat semi-span, the rotation of the slat element, the extension forward of the leading edge and the downward drop below the leading edge. An L9 orthogonal array (OA) was used to investigate the influence of these key design parameters using three performance criteria, namely the angle at which pitch break occurs, the corresponding speed and the distance between the Neutral point of each configuration and the Neutral point of the reference platform. The investigation was conducted by using high-fidelity Computational Fluid Dynamics (CFD) methods for each of the nine configurations defined by the L9 OA, over a range of angles of attack between −4 and 16 degrees. Based on these results, and using a Signal-to-Noise ratio (SNR) analysis, two combinations were eventually derived, one that optimized pitch break angle and speed and one that optimized longitudinal stability. Finally, the Pareto Analysis of Variance (ANOVA) technique was conducted to define the contribution of each of the six design parameters on the selected performance criteria. More specifically, the semi-span seemed to have the most significant effect on pitch break angle and speed, whereas the rotation of the slat element was the most important parameter with regard to static stability.
研究了翼身混合飞行器(BWB)前缘板条对其大迎角纵向稳定性的影响。采用实验设计(Design of Experiments, DOE)方法，具体地说，采用田口法，在三个不同的水平上研究了四个前缘板的设计参数。这些参数分别是板条半跨、板条单元的旋转、前缘向前延伸和前缘以下向下下降。采用L9正交阵列(OA)，通过三个性能标准，即俯距断裂发生的角度、相应的速度以及每种构型中性点与参考平台中性点之间的距离，研究了这些关键设计参数的影响。研究人员使用高保真计算流体动力学(CFD)方法对L9 OA定义的9种构型进行了研究，攻角范围在- 4到16度之间。基于这些结果，并使用信噪比(SNR)分析，最终导出了两种组合，一种优化了俯仰角和速度，另一种优化了纵向稳定性。最后，采用帕累托方差分析(ANOVA)技术来确定六个设计参数对所选性能标准的贡献。更具体地说，半跨似乎对俯仰角和速度的影响最显著，而板条单元的旋转是最重要的静稳定性参数。
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