{"title":"Abstracts of the Papers Published in Journal of the Japan Society for Aeronautical and Space Sciences (Vol. 68, No. 6, Dec. 2020)","authors":"","doi":"10.2322/tjsass.64.63","DOIUrl":"https://doi.org/10.2322/tjsass.64.63","url":null,"abstract":"","PeriodicalId":54419,"journal":{"name":"Transactions of the Japan Society for Aeronautical and Space Sciences","volume":"1 1","pages":""},"PeriodicalIF":1.1,"publicationDate":"2021-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"68663828","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}
T. Arakawa, Kiyoshi Nojima, Kan Kobayashi, S. Tomioka
An experimental investigation on fuel and air mixing characteristics within a dual-mode combustor is presented. To determine the dominant parameters of mixing characteristics of fuel with air fl ow, fuel (H 2 or C 2 H 4 ) or inert gas (He, N 2 or Ar) were perpendicularity injected from plural circular ori fi ces into high- or room-temperature M2.5 air fl ows decelerated through pseudo-shockwave systems. Under similar dynamic pressure ratios, fuel mass fl ux contours downstream of the injector were similar between the H 2 and C 2 H 4 reacting cases. However, fuel mass fl ux contours were di ff erent between the C 2 H 4 reacting and Ar non-reacting cases due to the heat-release e ff ect during local mixing. On the other hand, heat-release e ff ect on mixing e ffi ciency was found to be minor in bulk-scale mixing evaluation. It was found that C 2 H 4 mixing e ffi ciency with an equivalence ratio of 1.6 could be predicted within an error of a few percent from Ar mixing results under similar dynamic pressure ratio and similar peak pressure.
{"title":"Fuel/Air Mixing in Reacting and Non-reacting Flows within a Dual-mode Combustor","authors":"T. Arakawa, Kiyoshi Nojima, Kan Kobayashi, S. Tomioka","doi":"10.2322/TJSASS.64.71","DOIUrl":"https://doi.org/10.2322/TJSASS.64.71","url":null,"abstract":"An experimental investigation on fuel and air mixing characteristics within a dual-mode combustor is presented. To determine the dominant parameters of mixing characteristics of fuel with air fl ow, fuel (H 2 or C 2 H 4 ) or inert gas (He, N 2 or Ar) were perpendicularity injected from plural circular ori fi ces into high- or room-temperature M2.5 air fl ows decelerated through pseudo-shockwave systems. Under similar dynamic pressure ratios, fuel mass fl ux contours downstream of the injector were similar between the H 2 and C 2 H 4 reacting cases. However, fuel mass fl ux contours were di ff erent between the C 2 H 4 reacting and Ar non-reacting cases due to the heat-release e ff ect during local mixing. On the other hand, heat-release e ff ect on mixing e ffi ciency was found to be minor in bulk-scale mixing evaluation. It was found that C 2 H 4 mixing e ffi ciency with an equivalence ratio of 1.6 could be predicted within an error of a few percent from Ar mixing results under similar dynamic pressure ratio and similar peak pressure.","PeriodicalId":54419,"journal":{"name":"Transactions of the Japan Society for Aeronautical and Space Sciences","volume":"1 1","pages":""},"PeriodicalIF":1.1,"publicationDate":"2021-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"68664005","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}
Qiang Zhang, Fumiya Takahashi, Kotaro Sato, W. Tsuru, K. Yokota
We propose a tangential blowing cylinder, a type of circulation control wing, to control the direction of a jet replacing a blade or a cascade. Flow characteristics including de fl ection are experimentally investigated. Speci fi cally, visualization observations, velocity distribution measurements, and the e ff ects of momentum ratio, injection angle, and location of the cylinder on the de fl ection angle of the jet are analyzed. The stalling at an angle-of-attack above 20° with a single blade impedes direction control for such large angles. However, the jet may be bent to approximately 90° by using the proposed tangential blowing cylinder. The optimal injection angle for controlling the jet direction and the unsteady characteristics downstream of the tangential blowing cylinder are also determined.
{"title":"Jet Direction Control Using Circular Cylinder with Tangential Blowing","authors":"Qiang Zhang, Fumiya Takahashi, Kotaro Sato, W. Tsuru, K. Yokota","doi":"10.2322/TJSASS.64.181","DOIUrl":"https://doi.org/10.2322/TJSASS.64.181","url":null,"abstract":"We propose a tangential blowing cylinder, a type of circulation control wing, to control the direction of a jet replacing a blade or a cascade. Flow characteristics including de fl ection are experimentally investigated. Speci fi cally, visualization observations, velocity distribution measurements, and the e ff ects of momentum ratio, injection angle, and location of the cylinder on the de fl ection angle of the jet are analyzed. The stalling at an angle-of-attack above 20° with a single blade impedes direction control for such large angles. However, the jet may be bent to approximately 90° by using the proposed tangential blowing cylinder. The optimal injection angle for controlling the jet direction and the unsteady characteristics downstream of the tangential blowing cylinder are also determined.","PeriodicalId":54419,"journal":{"name":"Transactions of the Japan Society for Aeronautical and Space Sciences","volume":"1 1","pages":""},"PeriodicalIF":1.1,"publicationDate":"2021-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"68662761","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}
Koji Fujita, Kakeru Kurane, Koichi Takahashi, H. Nagai
The aerodynamic characteristics of a wing in a propeller slipstream were investigated at a low Reynolds number. The e ff ects of propeller position and rotation direction on the wing were clari fi ed by aerodynamic measurements and particle image velocimetry. The propeller positions were the center and tip of the wing model, whereas the rotation directions were clockwise and counterclockwise. The center propeller con fi guration with a clockwise rotation showed a constant pitching moment and increased the lift-to-drag ratio. This was caused by the high-speed propeller slipstream (i.e. 12 and 10m / s on the upwash and downwash sides, respectively) and the wingtip vortex e ff ect on the slipstream separation. The separation point at an angle-of-attack of 18° was delayed from x / c µ 0.1 to 0.3 by the wingtip vortex. Hence, the following two factors must be considered to enhance the aerodynamic characteristics of a Mars airplane: (i) the ratio of the area of the upwash and downwash sides of a wing in a propeller slipstream, and (ii) the e ff ect of the wingtip vortex on the propeller slipstream.
{"title":"Effects of Propeller Position and Rotation Direction on the Ishii Wing at a Low Reynolds Number","authors":"Koji Fujita, Kakeru Kurane, Koichi Takahashi, H. Nagai","doi":"10.2322/tjsass.64.22","DOIUrl":"https://doi.org/10.2322/tjsass.64.22","url":null,"abstract":"The aerodynamic characteristics of a wing in a propeller slipstream were investigated at a low Reynolds number. The e ff ects of propeller position and rotation direction on the wing were clari fi ed by aerodynamic measurements and particle image velocimetry. The propeller positions were the center and tip of the wing model, whereas the rotation directions were clockwise and counterclockwise. The center propeller con fi guration with a clockwise rotation showed a constant pitching moment and increased the lift-to-drag ratio. This was caused by the high-speed propeller slipstream (i.e. 12 and 10m / s on the upwash and downwash sides, respectively) and the wingtip vortex e ff ect on the slipstream separation. The separation point at an angle-of-attack of 18° was delayed from x / c µ 0.1 to 0.3 by the wingtip vortex. Hence, the following two factors must be considered to enhance the aerodynamic characteristics of a Mars airplane: (i) the ratio of the area of the upwash and downwash sides of a wing in a propeller slipstream, and (ii) the e ff ect of the wingtip vortex on the propeller slipstream.","PeriodicalId":54419,"journal":{"name":"Transactions of the Japan Society for Aeronautical and Space Sciences","volume":"1 1","pages":""},"PeriodicalIF":1.1,"publicationDate":"2021-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"68663147","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}
{"title":"TRANSACTIONS OF THE JAPAN SOCIETY FOR AERONAUTICAL AND SPACE SCIENCES .Notice Regarding Shift to Open Access","authors":"","doi":"10.2322/tjsass.64.248","DOIUrl":"https://doi.org/10.2322/tjsass.64.248","url":null,"abstract":"","PeriodicalId":54419,"journal":{"name":"Transactions of the Japan Society for Aeronautical and Space Sciences","volume":"1 1","pages":""},"PeriodicalIF":1.1,"publicationDate":"2021-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"68663579","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}
Due to their suitable characteristics for throttleable rocket engines, interest in pintle injectors has been recently re-newed. Many studies have focused on the correlation between spraying conditions and spray or combustion characteristics for pintle injector. However, there is no previous study on the correlation between spray and combustion characteristics due to the di ffi culties in controlling each spray characteristic individually. This research presents a solution to this problem. For the control group, a 400 N gas-liquid pintle injector for liquid oxygen and gas methane is designed and its spray characteristics are measured through cold- fl ow tests. In sequence, a ‘ reverse injection ’ idea and its design are proposed to increase spray angle while maintaining the droplet size, which is represented by the Sauter mean diameter. In addition, in the design proposed, the reverse injection e ff ect is intensi fi ed as the throttling level increases, decreasing the di ff erence of spray angle between throttling levels. In a cold- fl ow test, air and water were used under an atmospheric condition for gas-liquid fl ow simulant. The spray angle and droplet size were measured using the shadow method. The ‘ reverse injection ’ feature proposed functioned properly, increasing the spray angle of the injector while maintaining the droplet size.
{"title":"Droplet Size Control in Gas-Liquid Pintle Injectors","authors":"Daehwan Kim, Suji Lee, Y. Yoon","doi":"10.2322/TJSASS.64.91","DOIUrl":"https://doi.org/10.2322/TJSASS.64.91","url":null,"abstract":"Due to their suitable characteristics for throttleable rocket engines, interest in pintle injectors has been recently re-newed. Many studies have focused on the correlation between spraying conditions and spray or combustion characteristics for pintle injector. However, there is no previous study on the correlation between spray and combustion characteristics due to the di ffi culties in controlling each spray characteristic individually. This research presents a solution to this problem. For the control group, a 400 N gas-liquid pintle injector for liquid oxygen and gas methane is designed and its spray characteristics are measured through cold- fl ow tests. In sequence, a ‘ reverse injection ’ idea and its design are proposed to increase spray angle while maintaining the droplet size, which is represented by the Sauter mean diameter. In addition, in the design proposed, the reverse injection e ff ect is intensi fi ed as the throttling level increases, decreasing the di ff erence of spray angle between throttling levels. In a cold- fl ow test, air and water were used under an atmospheric condition for gas-liquid fl ow simulant. The spray angle and droplet size were measured using the shadow method. The ‘ reverse injection ’ feature proposed functioned properly, increasing the spray angle of the injector while maintaining the droplet size.","PeriodicalId":54419,"journal":{"name":"Transactions of the Japan Society for Aeronautical and Space Sciences","volume":"1 1","pages":""},"PeriodicalIF":1.1,"publicationDate":"2021-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"68664133","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}
This paper introduces a novel filter for hybrid attitude and orbit estimation of spacecrafts with geomagnetic measurements and its time-differential information. Geomagnetic measurements can be used for simultaneous attitude and orbit estimation of spacecrafts. In practice, the attitude estimation from a single magnetometer is achieved by fusing the magnetometer readings and their time derivatives together. The orbit will also be estimated according to the relationship between the geomagnetic model and spacecraft coordinates in the Earth geodetic frame. However, the magnetic time derivatives have not participated in estimating the orbit elements. According to the mathematical structures of the geomagnetic models, the time-differential feedback can effectively enhance the estimation of the velocity and thus will provide better performance for the position loop. This paper first introduces such direct feedback and formulates a new filter with better characteristics. The simulation study of a medium Earth orbit (MEO) Nadir-pointing satellite mission shows that the proposed filter achieves faster convergence and lower estimation errors.
{"title":"Hybrid Geomagnetic Attitude and Orbit Estimation Using Time-Differential Feedback","authors":"Jin Wu, Chengxi Zhang, Ming Liu","doi":"10.2322/TJSASS.64.174","DOIUrl":"https://doi.org/10.2322/TJSASS.64.174","url":null,"abstract":"This paper introduces a novel filter for hybrid attitude and orbit estimation of spacecrafts with geomagnetic measurements and its time-differential information. Geomagnetic measurements can be used for simultaneous attitude and orbit estimation of spacecrafts. In practice, the attitude estimation from a single magnetometer is achieved by fusing the magnetometer readings and their time derivatives together. The orbit will also be estimated according to the relationship between the geomagnetic model and spacecraft coordinates in the Earth geodetic frame. However, the magnetic time derivatives have not participated in estimating the orbit elements. According to the mathematical structures of the geomagnetic models, the time-differential feedback can effectively enhance the estimation of the velocity and thus will provide better performance for the position loop. This paper first introduces such direct feedback and formulates a new filter with better characteristics. The simulation study of a medium Earth orbit (MEO) Nadir-pointing satellite mission shows that the proposed filter achieves faster convergence and lower estimation errors.","PeriodicalId":54419,"journal":{"name":"Transactions of the Japan Society for Aeronautical and Space Sciences","volume":"64 1","pages":"174-180"},"PeriodicalIF":1.1,"publicationDate":"2021-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"68662726","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}
As a vast amount of data with respect to the moon and Mars is collected, exploration missions are shifting to the next step, the aim of which is a precise landing on a predetermined target. A promising technology for precision landing is terrain relative navigation (TRN), which collates landmarks detected from images and maps of landmarks. Crater detection is one of the essential technologies for TRN. A problem in detecting craters is the apparent change in craters due to illumination conditions. Another problem is the change in shape due to crater degradation. We propose a novel crater detection method based on combining a support vector machine (SVM) and a convolutional neural network (CNN) to make detection performance robust against apparent change. In the linear SVM, gradient images of a crater image dataset are learned. The learned classi fi er is then used to calculate the objectness score for region proposal. Next, the CNN identi fi es the image of the proposed region as to whether or not it is a crater. Our results show that the proposed method can detect craters in a wide range of illumination and shape conditions, and has better average precision than traditional crater de-tectors.
{"title":"Crater Detection Robust to Illumination and Shape Changes using Convolutional Neural Network","authors":"T. Ishida, Masaki Takahashi, S. Fukuda","doi":"10.2322/tjsass.64.197","DOIUrl":"https://doi.org/10.2322/tjsass.64.197","url":null,"abstract":"As a vast amount of data with respect to the moon and Mars is collected, exploration missions are shifting to the next step, the aim of which is a precise landing on a predetermined target. A promising technology for precision landing is terrain relative navigation (TRN), which collates landmarks detected from images and maps of landmarks. Crater detection is one of the essential technologies for TRN. A problem in detecting craters is the apparent change in craters due to illumination conditions. Another problem is the change in shape due to crater degradation. We propose a novel crater detection method based on combining a support vector machine (SVM) and a convolutional neural network (CNN) to make detection performance robust against apparent change. In the linear SVM, gradient images of a crater image dataset are learned. The learned classi fi er is then used to calculate the objectness score for region proposal. Next, the CNN identi fi es the image of the proposed region as to whether or not it is a crater. Our results show that the proposed method can detect craters in a wide range of illumination and shape conditions, and has better average precision than traditional crater de-tectors.","PeriodicalId":54419,"journal":{"name":"Transactions of the Japan Society for Aeronautical and Space Sciences","volume":"1 1","pages":""},"PeriodicalIF":1.1,"publicationDate":"2021-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"68663014","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}
A whirling arm is an effective device to measure propeller characteristics at low advance ratios. In the authors’ preceding research, an apparent advance ratio was adopted to determine propeller characteristics. The apparent advance ratio is determined only by the relative airspeed of the rotating arm and propeller in still air, and is used in wind tunnel measurements. However, in the case of whirling arm measurements, the advance ratio should be determined appropriately considering the additional airspeed induced by propeller wakes and swirling flow generated by the rotating arm. To address the above issue, we propose an airspeed model of blades considering velocity fields induced by the surrounding vortices. We also propose a procedure to calculate an appropriate advance ratio and the steady characteristics based on the proposed model. The validity of the proposed airspeed model is evaluated by making a comparison with the results of wind tunnel experiments. The corrected propeller characteristics using our airspeed model shows good consistency with the data referred from an existing propeller characteristics database.
{"title":"Modeling and Numerical Investigation of Aerodynamic Characteristics of a Propeller Circling on a Whirling Arm","authors":"Yuto Itoh, A. Satoh","doi":"10.2322/tjsass.64.335","DOIUrl":"https://doi.org/10.2322/tjsass.64.335","url":null,"abstract":"A whirling arm is an effective device to measure propeller characteristics at low advance ratios. In the authors’ preceding research, an apparent advance ratio was adopted to determine propeller characteristics. The apparent advance ratio is determined only by the relative airspeed of the rotating arm and propeller in still air, and is used in wind tunnel measurements. However, in the case of whirling arm measurements, the advance ratio should be determined appropriately considering the additional airspeed induced by propeller wakes and swirling flow generated by the rotating arm. To address the above issue, we propose an airspeed model of blades considering velocity fields induced by the surrounding vortices. We also propose a procedure to calculate an appropriate advance ratio and the steady characteristics based on the proposed model. The validity of the proposed airspeed model is evaluated by making a comparison with the results of wind tunnel experiments. The corrected propeller characteristics using our airspeed model shows good consistency with the data referred from an existing propeller characteristics database.","PeriodicalId":54419,"journal":{"name":"Transactions of the Japan Society for Aeronautical and Space Sciences","volume":"1 1","pages":""},"PeriodicalIF":1.1,"publicationDate":"2021-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"68664033","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}
{"title":"Abstracts of the Papers Published in Journal of the Japan Society for Aeronautical and Space Sciences (Vol. 69, No. 3, Jun. 2021)","authors":"","doi":"10.2322/tjsass.64.246","DOIUrl":"https://doi.org/10.2322/tjsass.64.246","url":null,"abstract":"","PeriodicalId":54419,"journal":{"name":"Transactions of the Japan Society for Aeronautical and Space Sciences","volume":"1 1","pages":""},"PeriodicalIF":1.1,"publicationDate":"2021-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"68663558","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}
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