Three-Dimensional Inviscid Flow Computations in a Spatial Turbopump Inducer Using a Distributed Loss Model

A Clebsch formulation, completely equivalent to the Euler equations is implemented from an Eulerian type variational principle. It leads to the decomposition of the velocity field into a potential and a rotational part and, thus, provides a unified solution scheme for potential and Euler equations. Although based on an inviscid flow model, this formulation includes a loss scheme. The numerical method uses a finite element discretization. Particular treatment of convection terms allows a low numerical diffusion. A pseudo time evolution enables a better stability behaviour. Numerical calculations have been performed on an industrial configuration of spatial turbopump. Different comparisons ere showed between measurements, calculations without and with distributed losses.

Blade Boundary Layer Effect on Turbine Erosion and Deposition

As an extension to the inviscid gas flow particle trajectory model presented in earlier papers, a complementary model has been developed to establish the effect of the blade boundary layer on the trajectories of particles and thus on the resulting erosion and/or deposition. The method consists essentially in tracing particles inside the boundary layer with initial conditions taken from the inviscid flow model. The flow data required for the particle trajectory calculations are obtained by using a compressible boundary layer flow computer program. This model has been applied to the first stage stator of a large electric utility gas turbine operating with coal gas. Results are compared with the predictions of the inviscid flow model. It is shown that the effect of the boundary layer on the trajectories of particles smaller than 6 μm is important. Since the hot gas cleaning system of a pressurized fluidized-bed gasifier system is projected to remove particles larger than 6 μm diameter effectively, it is concluded that an accurate assessment of turbine erosion and deposition requires inclusion of the boundary layer effect. Although these results emphasize the relative importance of the blade boundary layer, the absolute accuracy of the method remains to be demonstrated and is thought to be largely dependent on the basic data concerning the erosivity and sticking probability of particles.

Analysis of Flow Field and Impingement Heat/Mass Transfer Due to a Nonuniform Slot Jet

An analysis is made of the fluid flow and heat transfer characteristics associated with the impingement of a slot jet which issues from a delivery duct with a nonuniform velocity profile. Consideration is given to velocity profiles similar to that for a fully developed laminar channel flow. The velocity field within the impinging jet is solved for within the framework of an inviscid flow model. Results from the inviscid solution are used as input for the analysis of the boundary layer heat or mass transfer on the impingement surface. The stagnation point heat (or mass) transfer coefficients corresponding to the initially nonuniform velocity profile are found to be almost twice as large as those for an initially flat velocity profile. Furthermore, the transfer coefficients are insensitive to the separation distance between the duct exit and the impingement surface, within the range investigated. The analytical results compared satisfactorily with experimentally determined mass transfer coefficients.