Improved design of subcritical and supercritical cascades using complex characteristics and boundary-layer correction

This paper presents a new finite volume cell-centered scheme for solving the 2D Euler equations. The technique for computing the advective derivatives is based on a high-order Gauss quadrature and an original quadratic reconstruction of the conservative variables for each control volume. A very sensitive detector identifying discontinuity regions switches the scheme to a TVD scheme, and ensures the monotonicity of the solution. The code uses unstructured meshes whose cells are polygons with any number of edges. A mesh adaptation based on cell division is performed in order to increase the resolution of shocks. The accuracy, insensitivity to grid distortions as well as the shock capturing properties of the scheme are demonstrated for different cascade flow computations.

Section: Resultsmentioning

confidence: 99%

Finite Volume Scheme With Quadratic Reconstruction on Unstructured Adaptive Meshes Applied to Turbomachinery Flows

Delanaye

Essers

1995

“…Recently, a fully three-dimensional technique for designing the shapes of turbomachine blades for large deflections was proposed (Hawthorne et al, 1984;Tan et al, 1984). In this method, the Circulation Method, the primary prescribed flow quantity is the pitch-averaged tangential_ velocity in the bladed region, denoted by V e .…”

Section: Introductionmentioning

confidence: 99%

“…What is the significance of specifying the pitch-averaged tangential velocity distribution in the bladed region? At first, it appears that the most useful choice (also the conventionally preferred choice) for the prescribed flow conditions in an inverse method are the pressure distributions along the blade pressure and suction surfaces (Sanz, 1984). These pressure distributions are chosen to avoid flow separations on the blade surfaces at the design condition.…”

Section: Introductionmentioning

confidence: 99%

“…Novak & Haymann-Haber (1983) and Tan et al (1984) have shown that the local rate of change of rV e along the "blade streamwise" direction is related to the blade loading. Although the specification of the blade loading seems relatively arbitrary, this type of design-specification is used by many design offices in their onedimensional mean-streamline method (Holbrook & Brasz, 1984), two-dimensional inverse method (Novak & Haymann-Haber, 1983), and quasi-threedimensional streamline curvature methods (Smith, 1987).…”

Section: Introductionmentioning

confidence: 99%

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Design of Multi-Stage Turbomachinery Blading by the Circulation Method: Actuator Duct Limit

Dang

Wang

1992

This paper presents an extension of a recently developed three-dimensional inverse method for turbomachine blades to handle multi-stage machines in the limit of an infinite number of blades in each blade row. The axisymmetric flowfield is assumed to be inviscid, compressible, and rotational. The use of blockage and entropy-increase terms are included in the theory to model losses. An iterative procedure is presented for the calculations of the blade profiles which produce prescribed swirl schedules in the bladed regions. The numerical technique employed to solve the relevant equations is based on a finite-volume formulation. The method is applied to the design of a low-pressure multi-stage centrifugal compressor used in industrial processing.

“…In the past, the problem was solved mostly by a trial-and-error approach which would largely depend on the designers a priori knowledge of how certain parameters must be modified in order to achieve the desired performance. In more recent years, two-dimensional fully inverse methodologies have been developed and can now be employed to design blade profiles more readily (Leonard & Van 'den Braembussche, 1992;Novak & Haymann-Haber, 1983;Sanz, 1984). These inverse methods are based on the idea of specifying a certain desired flowfield quantity and solving for the corresponding blade shape.…”

mentioning

confidence: 99%

Inverse Method for Turbomachine Blades Using Existing Time-Marching Techniques

Dang

Isgro

1994

A newly-developed inverse method for the design of turbomachine blades using existing time-marching techniques for the numerical solutions of the unsteady Euler equations is proposed. In this inverse method, the pitch-averaged tangential velocity (or the blade loading) is the specified quantity, and the corresponding blade geometry is Iteratively sought after. The presence of the blades are represented by a periodic array of discrete body forces which are included in the equations of motion. A four-stage Runge-Kutta time-stepping scheme is used to march a finite-volume formulation, of the unsteady Euler equations to a steady-state solution. Modification of the blade geometry during this time marching process is achieved using the slip boundary conditions on the blade surfaces. This method is demonstrated for the design of infinitely-thin cascaded blades in the subsonic, transonic, and supersonic flow regimes. Results are validated using an Euler analysis method and are compared against those obtained using a similar inverse method. Excellent agreement in the results are obtained between these different approaches.