Aiming at the safety problem of the stage separation of parallel reusable high-speed air vehicles,this paper studies the unsteady test method and focuses on deriving a similarity law of parallel stage separation free-...Aiming at the safety problem of the stage separation of parallel reusable high-speed air vehicles,this paper studies the unsteady test method and focuses on deriving a similarity law of parallel stage separation free-flight wind tunnel tests.The new similarity law considers the influences of aerodynamic force and gravity on the motions of the two stages,as well as the influence of aerodynamic interference between the two stages on each other’s motion.From the perspective of multiangle physical equations,the conditions to ensure that the two-stage separation trajectory of a wind tunnel test is similar to that of a real air vehicle are derived innovatively,so as to ensure the authenticity and credibility of wind tunnel test results.The similarity law is verified by an HIFiRE-5 air vehicle,and the separation trajectories of wind tunnel tests and the real air vehicle are obtained by numerical simulation.The research shows that the similarity law derived in this paper can ensure that wind tunnel free-flight tests have the ability to predict the two-stage separation characteristics of real parallel vehicles.By analyzing the separation trajectory curve of the typical state,it is found that the new method can ensure that the trajectory error of a wind tunnel test does not exceed 1%,which indicates that this method is credible.The establishment of the new method lays the foundation for subsequent wind tunnel tests and provides support for research on the safety of the stage separation of parallel reusable air vehicles.展开更多
Based on the research result on the strake-wing, when the size of a strakeis not large, there is a separation zone near the leading edge of the outwing of thestrake-wing at middle angles of attack. So the idea on sepa...Based on the research result on the strake-wing, when the size of a strakeis not large, there is a separation zone near the leading edge of the outwing of thestrake-wing at middle angles of attack. So the idea on separation control by rotating acone placed near the leading edge is presented. The cone surface consists of the part ofthe wing. The effect of rotating the cone on aerodynamic characteristics of thestrake-wing is investigated. The results show that a rotating surface could play an important role in controlling the flow separation for a 3-dimensional wing. For example,the relative increment in maximum lift coefficient attains 30%. The separation zone issuppressed to a certain extent.展开更多
In view of the separation form of the separator from the back of the carrier upward and from the side of the carrier outward, separation-safety research is carried out by taking the separation of a cluster munition as...In view of the separation form of the separator from the back of the carrier upward and from the side of the carrier outward, separation-safety research is carried out by taking the separation of a cluster munition as an example. In previous wind tunnel free-flight tests, the similarity law of vertical, downward, moving submunition was used to design submunitions at different positions in different initial-velocity directions, which resulted in large discrepancies between wind tunnel test results and real flight. In a wind tunnel test, each submunition has an independent time-reduction ratio with respect to the dispenser. Even if the separation trajectory of a single submunition is accurate, there will be errors in the position of each submunition at a given time. Therefore, it is necessary to determine the time-reduction ratio between submunitions, and to modify the test results later. In order to ensure the accuracy of wind tunnel test results, the similarity law of a freeflight test in a wind tunnel is derived in this paper. The time-correction scheme to ensure motion similarity between submunitions is solved. Numerical simulation is used to simulate the separation of a wind tunnel test and real aircraft, and the motion parameters of different submunitions are solved. The results show that the new similarity laws derived for different types of submunitions can greatly reduce the errors caused by previous similarity laws. In addition to the case for the separation of a cluster munition, the similarity law can also be applied to the free-flight test design of wind tunnels for vertical separation and horizontal separation of other kinds of aircraft.展开更多
Aimed at the problem of store separation from internal cavity,this paper innovatively puts forward a separation scheme of using lateral jet to assist store safe separation.The jet ensures that the store is continuousl...Aimed at the problem of store separation from internal cavity,this paper innovatively puts forward a separation scheme of using lateral jet to assist store safe separation.The jet ensures that the store is continuously subjected to down head moment during separation,so as to ensure safe separation.The wind tunnel free drop test technique with lateral jet is established,which can ensure that there is no support interference in the motion process of the store and more truly simulate the motion of the store.The feasibility of the new separation scheme is proved by wind tunnel test.The test shows that the new scheme can also change the more dangerous state into a safe state.Through the analysis of the test data,the pitching moment coefficients of the store under different pressures in the high-pressure cylinder are obtained,and the effects of aircraft and cavity on the pitching moment of the store are obtained.The 3 stages of store passing through cavity shock wave are found.The results show that the lateral jet provides the store with continuous head down moment,and makes the store overcome the head up moment caused by the shock wave in front of the cavity,so as to ensure the safety of separation.展开更多
基金supported by the National Natural Science Foundation of China(Nos.U21B2054 and 11772317).
文摘Aiming at the safety problem of the stage separation of parallel reusable high-speed air vehicles,this paper studies the unsteady test method and focuses on deriving a similarity law of parallel stage separation free-flight wind tunnel tests.The new similarity law considers the influences of aerodynamic force and gravity on the motions of the two stages,as well as the influence of aerodynamic interference between the two stages on each other’s motion.From the perspective of multiangle physical equations,the conditions to ensure that the two-stage separation trajectory of a wind tunnel test is similar to that of a real air vehicle are derived innovatively,so as to ensure the authenticity and credibility of wind tunnel test results.The similarity law is verified by an HIFiRE-5 air vehicle,and the separation trajectories of wind tunnel tests and the real air vehicle are obtained by numerical simulation.The research shows that the similarity law derived in this paper can ensure that wind tunnel free-flight tests have the ability to predict the two-stage separation characteristics of real parallel vehicles.By analyzing the separation trajectory curve of the typical state,it is found that the new method can ensure that the trajectory error of a wind tunnel test does not exceed 1%,which indicates that this method is credible.The establishment of the new method lays the foundation for subsequent wind tunnel tests and provides support for research on the safety of the stage separation of parallel reusable air vehicles.
文摘Based on the research result on the strake-wing, when the size of a strakeis not large, there is a separation zone near the leading edge of the outwing of thestrake-wing at middle angles of attack. So the idea on separation control by rotating acone placed near the leading edge is presented. The cone surface consists of the part ofthe wing. The effect of rotating the cone on aerodynamic characteristics of thestrake-wing is investigated. The results show that a rotating surface could play an important role in controlling the flow separation for a 3-dimensional wing. For example,the relative increment in maximum lift coefficient attains 30%. The separation zone issuppressed to a certain extent.
基金supported by the Advanced Research Fund for Weapons and Equipment Development of China。
文摘In view of the separation form of the separator from the back of the carrier upward and from the side of the carrier outward, separation-safety research is carried out by taking the separation of a cluster munition as an example. In previous wind tunnel free-flight tests, the similarity law of vertical, downward, moving submunition was used to design submunitions at different positions in different initial-velocity directions, which resulted in large discrepancies between wind tunnel test results and real flight. In a wind tunnel test, each submunition has an independent time-reduction ratio with respect to the dispenser. Even if the separation trajectory of a single submunition is accurate, there will be errors in the position of each submunition at a given time. Therefore, it is necessary to determine the time-reduction ratio between submunitions, and to modify the test results later. In order to ensure the accuracy of wind tunnel test results, the similarity law of a freeflight test in a wind tunnel is derived in this paper. The time-correction scheme to ensure motion similarity between submunitions is solved. Numerical simulation is used to simulate the separation of a wind tunnel test and real aircraft, and the motion parameters of different submunitions are solved. The results show that the new similarity laws derived for different types of submunitions can greatly reduce the errors caused by previous similarity laws. In addition to the case for the separation of a cluster munition, the similarity law can also be applied to the free-flight test design of wind tunnels for vertical separation and horizontal separation of other kinds of aircraft.
基金supported by the National Natural Science Foundation of China(Nos.U21B2054,11772317)supported by the Open Fund of Key Laboratory of Icing and Anti/Deicing,China(No.IADL20200408).
文摘Aimed at the problem of store separation from internal cavity,this paper innovatively puts forward a separation scheme of using lateral jet to assist store safe separation.The jet ensures that the store is continuously subjected to down head moment during separation,so as to ensure safe separation.The wind tunnel free drop test technique with lateral jet is established,which can ensure that there is no support interference in the motion process of the store and more truly simulate the motion of the store.The feasibility of the new separation scheme is proved by wind tunnel test.The test shows that the new scheme can also change the more dangerous state into a safe state.Through the analysis of the test data,the pitching moment coefficients of the store under different pressures in the high-pressure cylinder are obtained,and the effects of aircraft and cavity on the pitching moment of the store are obtained.The 3 stages of store passing through cavity shock wave are found.The results show that the lateral jet provides the store with continuous head down moment,and makes the store overcome the head up moment caused by the shock wave in front of the cavity,so as to ensure the safety of separation.
