Influence of Process Parameters on Forming Load of Variable-Section Thin-Walled Conical Parts in Spinning

Thin-walled conical parts with variable-section are usually made of superalloy material, with poor plasticity and complex forces, which are difficult to form and control. In this research, a thin-walled conical casing of superalloy GH1140 with variable-section is studied; the real stress–strain curve of the material is fitted and the load-displacement curves of superalloy GH1140 are obtained through a universal testing machine. To clarify the equivalent stress distribution on the upper surface of the thin-walled casing during the forming process and after unloading the rotary wheel, the finite element model of the thin-walled conical casing during the spinning forming process is established with the Simufact Forming finite element analysis software. The effects of processing parameters, such as the mandrel rotational speed ω, the roller feed ratio f and the gap deviation rate δ between the roller and mandrel, on the spinning forming load were obtained. The distribution and numerical trend of the tangential residual stress after forming were detected by X-ray diffraction, and the causes of defects such as flange instability were analyzed. The results of the forming test and the test of residual stress conform well with the simulation, which verifies the stability of the model. The research provides a theoretical basis for improving the forming quality of thin-walled parts with variable-section.

Three Dimensional Transonic Flow Measurements in an Axial Turbine With Conical Walls

To investigate the spatial flow structure caused by sweep and dihedral effects in turbomachinery blade rows, detailed measurements have been conducted in the windtunnel for rotating annular cascades of DLR-Göttingen. The special configuration investigated, consisted of a turbine rotor equipped with straight blades, a conical hub and a conical casing with a cone half-angle of 30°. Numerous flow data are obtained from surface pressure distributions at seven radial blade sections and from Laser velocimetry upstream, downstream and inside the rotor. As the Laser-Two-Focus technique is a two-dimensional one, two laser velocity measurements at different angles bad to be taken at each meaurement location in the flow, in order to get the three components of velocity. The measurement accuracy of the three derived Mach number components in the blade relative system has been evaluated and stored together with mean and fluctuating values at each measurement location.

Frictional Resistance of Enclosed Rotating Cones With Superposed Throughflow

The research summarized in this paper is an experimental study of the frictional moment on a cone rotating in a conical casing with an outward throughflow. The cone vertex angles tested in the present experiment are θ = 30, 60 and 90 deg. In the region where the frictional moment on the rotating cone with no throughflow is increased by the effect of Taylor-type vortices, an increase of the throughflow rate results in a decrease of the frictional moment, if the throughflow rate is not so large. In the region where the Taylor-type vortices have no appreciable effect on the frictional moment, on the other hand, the rate of increase in CM with increasing Cq. sin (θ/2) is almost independent of θ, where CM and Cq denote the moment coefficient and the dimensionless throughflow rate, respectively.