CN-115292850-B - Method for designing molded line of rotary forming supersonic direct-connection simulator with shift shaft

CN115292850BCN 115292850 BCN115292850 BCN 115292850BCN-115292850-B

Abstract

A design method of a molded line of a rotary forming supersonic direct-connection simulator with a moving shaft belongs to the field of aerodynamic tests. The method comprises the steps of 1, obtaining a throat initial value line and a supersonic development line of a direct-connection simulator by utilizing an improved method for solving the flow of the cross-sound velocity and the axial characteristic points according to the geometric condition limitation of the moving shaft distance, 2, selecting and determining a contraction section line according to inlet conditions, throat area and curve parameters of the contraction section, and 3, obtaining an inlet shape by combining the contraction section obtained in the step 2 and the supersonic development line obtained in the step 1 according to the requirement of the outlet section shape of the simulator in a spinning mode. The supersonic direct-connection simulator has no complex actuation control mechanism, is realized by a pneumatic principle, and has a simple and reliable structure.

Inventors

GAO LIANGJIE
WANG LU
QIAN ZHANSEN
MENG FANMIN
LIU ZHONGCHEN
XIN YANAN

Assignees

中国航空工业集团公司沈阳空气动力研究所
中国航空工业集团公司沈阳空气动力研究所

Dates

Publication Date: 20260421
Application Date: 20220829
Priority Date: 20220829

Claims (2)

1. A design method of a molded line of a rotary forming supersonic direct-connection simulator with a moving shaft, the cross section of the simulator comprises an inlet section (1), a shrinkage and expansion curved surface (2), an outlet section (3) and a central spiral wall (4) which are sequentially and continuously arranged, and is characterized by comprising the following steps: Step 1, obtaining an initial value line and a supersonic development line of a throat of a direct-connection simulator by utilizing an improved method for solving the supersonic flow and axial characteristic points according to the geometric condition limitation of the moving shaft distance, wherein the method comprises the following specific implementation steps: step 11, determining an outlet area relation according to the outlet condition of the direct-connected simulator; the subsonic airflow is continuously accelerated in a channel 2 surrounded by an inlet entering shrinkage and supersonic development line of the direct-connected simulator, and at the minimum section of the channel, namely, the throat position reaches the sound velocity at first, the airflow is further accelerated to the supersonic velocity in the expansion section until reaching the design Mach number required by an outlet of the simulator, and the relation between the design Mach number and the area of the outlet is deduced by a flow formula in the simulator, wherein the relation between the design Mach number and the area of the outlet is as follows: ; Wherein, the For the simulator exit area, For the minimum cross-sectional area of the simulator, For the simulator exit mach number, Is the specific heat ratio of the gaseous medium; Step 12, designing a supersonic development line of the spray pipe according to a characteristic line theory, wherein the relation is as follows: ; Wherein, the In the form of an abscissa or an axial coordinate, In the form of an ordinate or a radial coordinate, For the local air flow direction angle, In order to be at the local mach number angle, For flow velocities in the transverse or axial direction, For a flow velocity in the longitudinal or radial direction, For the local speed of sound, A two-dimensional flow is represented and, The flow is represented by an axisymmetric flow, Subscript + -represents the right or left row direction along the feature line; Is the slope of the feature line; Step 13, setting an initial value line when the characteristic line method is used for calculating the supersonic flow field, taking the initial value line as a boundary condition of the characteristic line method, solving a wall profile by combining Mach number distribution on a central axis, determining the initial characteristic line by throat transonic velocity analysis solution, combining the axial Mach number distribution to obtain a characteristic line network in the spray pipe, and obtaining an ultrasonic section profile on a characteristic line grid by using a streamline tracking method; Step 14, generating a power series of y by using the disturbance function, wherein each coefficient is a function of x, determining the coefficient functions by using boundary conditions, and performing axis shifting on the original conditions: the curve corresponding to the disturbance speed of 0 in the y direction is used as an initial line, and the equation of the initial line with the moving shaft can be obtained as follows: ; Wherein, the For the desired axial displacement distance, i.e. the radial distance of the centering wall (4) from the virtual rotation axis 5, For the laryngeal profile curvature, it is determined by the following relationship: ; Wherein, the Is the radial height of the dimensionless throat, Is a dimensionless laryngeal curvature; the supersonic development molded line is obtained by using a reverse characteristic line design method, namely Mach number distribution with continuity and smoothness meeting requirements is firstly arranged on an axis, the wall surface curvature is ensured to be continuous, the Mach number of the axis needs to meet the second derivative continuity, and the Mach number distribution is given by adopting a proper interpolation method, so that the requirements at the boundary of the axis are met: ; The point B is the intersection point of the transonic initial line and the axis, and the point C is the intersection point of the downstream left-hand characteristic line of the supersonic development line and the axis; step 2, selecting and determining a contraction section molded line according to inlet conditions, throat area and contraction section curve parameters; And 3, according to the requirements of the section shape of the outlet of the simulator, combining the contraction section obtained in the step 2 and the supersonic development line obtained in the step 1, and obtaining the shape of the inlet through a spinning mode.
2. The method for designing the molded line of the belt-moving shaft-rotating forming type supersonic direct-connection simulator is characterized in that a shrinking section molded line in the step2 adopts a conventional design method of a hyperbolic curve or a quintic curve.

Description

Method for designing molded line of rotary forming supersonic direct-connection simulator with shift shaft Technical Field The invention relates to a linear design method of a supersonic direct-connection simulator, and belongs to the field of aerodynamic tests. Background Supersonic simulators are widely used in the field of aerospace aerodynamic tests for constructing flow field structures that meet certain outflow conditions. Typical supersonic simulators such as wind tunnels or ejector nozzles obtain curves with contraction and expansion characteristics through specific designs, and under the condition of a certain pressure ratio, a required supersonic flow structure can be formed at the outlet of the nozzle, and the distribution of outlet flow field parameters can be uniform or nonuniform. Such simulators typically have a two-dimensional or axisymmetric flow characteristic in which for a two-dimensional structure the axis of symmetry is located on a plane of symmetry and the simulator outlet is generally square or rectangular, and for an axisymmetric structure the axis of rotation is located on a central axis and the simulator outlet is generally circular. The wall surface curve consists of a subsonic velocity contraction section, a throat section and a supersonic velocity expansion section. The contraction section adopts three or five fairing curves, the throat section adopts a transonic flow field solution as an initial value line, the supersonic expansion section adopts a characteristic line theory as a basis (combined with an interfacial layer correction technology), and the design method can be classified into two categories: One is a partial feature line design method based on the spring current assumption, such as Foelsch method and a Crown method. The general idea is to change the sonic flow at the throat into the supersonic current of spring at the turning point by using the anterior segment multiple curves. The method has the defects that the curve of the wall surface at the turning point is not conductive, the disturbance exists in the flow field, and the overall performance of the simulator is greatly influenced. To increase the smoothness of the simulator wall, an improved design method with continuous curvature is produced on the basis of the above method, such as Kenney, which smoothes the transition profile by predefining a wall profile after the turning point. Although the improvement method improves the quality of the outlet flow field to a certain extent, the spring flow assumption is adopted, so that the design of the line before the turning point lacks theoretical basis. The other type is a complete feature line method, and can be further classified into a direct feature line method and a reverse feature line method. The direct characteristic line method determines boundary characteristic line parameters and positions according to the number of design Mas of the simulator outlet by specifying the curve form (such as circular arc) of the expansion section close to the throat. The non-sticky boundary can be obtained by combining the flow line tracking technology with the distribution (such as axial Mach number or speed distribution) of given axial flow parameters by the reverse characteristic line method. In comparison, the full feature line method cancels the current of spring region assumption, enhances the theoretical basis of design, and thus the quality of the possibly obtained flow field is better. In recent years, the design requirements for simulators with a rotary structure are increasing, and in particular, it is desired to design a direct-connection simulator capable of directly providing a near-wall ultrasonic flow research requirement of an arc-shaped structural member. From the aspects of geometry and flow characteristics, this type of simulator is different from the traditional two-dimensional or axisymmetric nozzle, so that the expansion characteristics are different from those of the two-dimensional or axisymmetric nozzle, and further development in design methods is required in order to achieve higher outlet flow field quality. Disclosure of Invention The invention aims to provide a rotary forming type supersonic speed direct connection simulator with a moving shaft, which can greatly improve the supersonic speed flow field simulation capability with a rotary forming structure and improve the outlet quality. The following presents a simplified summary of the invention in order to provide a basic understanding of some aspects of the invention. It should be understood that this summary is not an exhaustive overview of the invention. It is not intended to identify key or critical elements of the invention or to delineate the scope of the invention. The technical scheme of the invention is as follows: the invention relates to a design method of a linear line of a rotary forming supersonic speed direct connection simulator with a moving shaft, wherein the cross section o