Experimental and analytical investigation of flow through rocket pump inducer

The characteristics of a rocket pump inducer are discussed. The effect of the pumping requirements on the blade configuration is analyzed. The effects of viscosity on blade design were determined by tests of a four bladed inducer operated in air at a flow coefficient of 0.065. The fluid properties were measured at the exit of the inducer using conventional and hot wire probes. The experimental results and the method of predicting the outlet tangential velocity and head rise are discussed

Compressor and fan wake characteristics

Approaches for developing an analytical model capable of determining the effects of rotor flow and blade parameters and turbulence properties (i.e. energy, velocity correlations, and length scale) on the rotor wake characteristics and its diffusion properties are discussed. The three-dimensional model will employ experimental measurements, instantaneous velocities, and turbulence properties at various stations downstream from a rotor. A triaxial probe and a rotating conventional probe, which is mounted on a traverse gear operated by two step motors, are to be used for these measurements. The final rotor wake model will be capable of predicting the discrete and broadband noise generated in a fan rotor and of evaluating the aerodynamic losses, efficiency and optimum spacing between a rotor and stator in turbomachinery

End wall flow characteristics and overall performance of an axial flow compressor stage

This review indicates the possible future directions for research on endwall flows in axial flow compressors. Theoretical investigations on the rotor blade endwall flows in axial flow compressors reported here include the secondary flow calculation and the development of the momentum integral equations for the prediction of the annulus wall boundary layer. The equations for secondary vorticity at the rotor exit are solved analytically. The solution includes the effects of rotation and the viscosity. The momentum integral equations derived include the effect of the blade boundary layers. The axial flow compressor facility of the Department of Aerospace Engineering at The Pennsylvania State University, which is used for the experimental investigations of the endwall flows, is described in some detail. The overall performance and other preliminary experimental results are presented. Extensive radial flow surveys are carried out at the design and various off design conditions. These are presented and interpreted in this report. The following experimental investigations of the blade endwall flows are carried out. (1) Rotor blade endwall flows: The following measurements are carried out at four flow coefficients. (a) The rotor blade static pressures at various axial and radial stations (with special emphasis near the blade tips). (b) The hub wall static pressures inside the rotor blade passage at various axial and tangential stations. (2) IGV endwall flows: The following measurements are carried out at the design flow coefficient. (a) The boundary layer profiles at various axial and tangential stations inside the blade passage and at the blade exit. (b) Casing static pressures and limiting streamline angles inside the blade passage

On the investigation of cascade and turbomachinery rotor wake characteristics

The objective of the investigation reported in this thesis is to study the characteristics of a turbomachinery rotor wake, both analytically and experimentally. The constitutive equations for the rotor wake are developed using generalized tensors and a non-inertial frame of reference. Analytical and experimental investigation is carried out in two phases; the first phase involved the study of a cascade wake in the absence of rotation and three dimensionality. In the second phase the wake of a rotor is studied. Simplified two- and three-dimensional models are developed for the prediction of the mean velocity profile of the cascade and the rotor wake, respectively, using the principle of self-similarity. The effect of various major parameters of the rotor and the flow geometry is studied on the development of a rotor wake. Laws governing the decay of the wake velocity defect in a cascade and rotor wake as a function of downstream distance from the trailing edge, pressure gradient and other parameters are derived

Characteristics of lightly loaded fan rotor blade wakes

Low subsonic and incompressible wake flow downstream of lightly loaded rotor was studied. Measurements of mean velocity, turbulence intensity, Reynolds stress, and static variations across the rotor wake at various axial and radial locations were investigated. Wakes were measured at various rotor blade incidences to discern the effect of blade loading on the rotor wake. Mean velocity and turbulence measurements were carried out with a triaxial hot wire probe both rotating with the rotor and stationary behind the rotor. Results indicate that increased loading slows the decay rates of axial and tangential mean velocity defects and radial velocities in the wake. The presence of large radial velocities in the rotor wake indicate the extent of the interactions between one radius and another. Appreciable static pressure variations across the rotor wake were found in the near wake region. Similarity in the profile shape was found for the axial and tangential components of the mean velocity and in the outer layer for axial, tangential, and radial turbulence intensities

Investigations of three dimensional flow characteristics in a three bladed rocket pump inducer

Because of the long and narrow passages between the blades of a rocket pump inducer, major effects from turbulence and viscosity make the flow through such a device truly three-dimensional and therefore difficult to measure or predict. To investigate the flow characteristics, conventional and three-dimensional hot-wire probe measurements were conducted in a model inducer 3 ft in diameter. Blade-to-blade variation of the three components of velocity at the exit and the corresponding turbulence intensities were obtained by means of hotwire probes aligned in the three coordinate directions. Analysis of the three-dimensional inviscid flow field led to qualitative prediction of the flow characteristics. Extensive measurements and theoretical analyses of the flow field showed that blade blockage, viscosity, and blade boundary layer interactions are the dominant influences on flow in this type of turbomachinery

Three dimensional analysis and measurement of the flow in a three bladed rocket pump inducer

Three dimensional analysis and measurement of flow in three bladed pump inducer for liquid rocket engin

A modified crack closure integral method for calculating stress intensity factors for cracked plates subject to bending loads

A method is developed to calculate strain energy release rates, G, or stress intensity factors, K, using only nodal forces and displacements from a standard finite element analysis code. The method is an extension of the modified crack closure integral (MCCI) approach to the bending of plates with through cracks. An examination of bending of plates with through cracks based on shear deformation theories has shown that the bending K depends strongly on the ratio of plate thickness, h, and half crack length, a. Hence, the need to examine the effect of h/a on the accuracy of G and K obtained by the MCCI approach is examined. The accuracy of the MCCI method is verified by analyzing a square plate with a central crack subjected to a uniform edge moment and comparing the results with those reported in the literature

Coordinated Multi-cell Beamforming for Massive MIMO: A Random Matrix Approach

We consider the problem of coordinated multi- cell downlink beamforming in massive multiple input multiple output (MIMO) systems consisting of N cells, Nt antennas per base station (BS) and K user terminals (UTs) per cell. Specifically, we formulate a multi-cell beamforming algorithm for massive MIMO systems which requires limited amount of information exchange between the BSs. The design objective is to minimize the aggregate transmit power across all the BSs subject to satisfying the user signal to interference noise ratio (SINR) constraints. The algorithm requires the BSs to exchange parameters which can be computed solely based on the channel statistics rather than the instantaneous CSI. We make use of tools from random matrix theory to formulate the decentralized algorithm. We also characterize a lower bound on the set of target SINR values for which the decentralized multi-cell beamforming algorithm is feasible. We further show that the performance of our algorithm asymptotically matches the performance of the centralized algorithm with full CSI sharing. While the original result focuses on minimizing the aggregate transmit power across all the BSs, we formulate a heuristic extension of this algorithm to incorporate a practical constraint in multi-cell systems, namely the individual BS transmit power constraints. Finally, we investigate the impact of imperfect CSI and pilot contamination effect on the performance of the decentralized algorithm, and propose a heuristic extension of the algorithm to accommodate these issues. Simulation results illustrate that our algorithm closely satisfies the target SINR constraints and achieves minimum power in the regime of massive MIMO systems. In addition, it also provides substantial power savings as compared to zero-forcing beamforming when the number of antennas per BS is of the same orders of magnitude as the number of UTs per cell

Blade end wall flows in compressors

A brief summary of previous work carried out on end wall flow phenomena is presented with major emphasis on annulus wall boundary layer