Radial versus Diagonal Diffusion in Multi-Stage Pumps

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radialanddiagonaldiffusion
Radial and Diagonal Diffusion

Although crossover design has only a secondary effect on pump efficiency, it too should use every available trick to achieve the best possible results.

This picture (left and below) shows short and long configurations of the two basic types of crossovers normally used on multi-stage pumps. Both have been tested by the West Coast pump companies and the results of these tests indicate that the radial diffusion type is approximately one point more efficient than the diagonal diffusion type. Here’s why: Continue reading “Radial versus Diagonal Diffusion in Multi-Stage Pumps”

Let’s Talk About Centrifugal Compressors

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centrifugalcompressordesign
Centrifugal Compressor Design

We all know by now that no machine is perfect. Turbines have carryover losses, pumps experience cavitation phenomena, and compressors certainly have their fair share of pros and cons. We’re on the hunt for some common design problems – perhaps problems that you have experienced yourself, with centrifugal compressors. We scoured through our technical papers and presentations and searched the web for some. Here’s a list of frequent concerns and questions we ran into: Continue reading “Let’s Talk About Centrifugal Compressors”

Shortening Start-Up Time and Life Prediction of Critical Components

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steamturbine
Steam Turbine

This month we’re hosting the third segment to our Steam Turbine Webinar Series.

Shortening Start-Up Time and Life Prediction of Critical Components

Shortening  turbine start-up is a main concern for power machinery operators and manufacturers – is it a concern of yours? Continue reading “Shortening Start-Up Time and Life Prediction of Critical Components”

5 Steps to Advanced 3D Blade Design

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3dbladedesign
3 Blade Design

To decrease losses and increase performance of a turbine, we need to develop special (compound) geometries. Here’s your turbomachinery cheat sheet to advanced 3D blade design!

1. Optimizing plane profiling

There are several positive things that can give proper plane sections profiling: decreasing the profile losses, decreasing secondary losses and satisfying structural limitations. Continue reading “5 Steps to Advanced 3D Blade Design”

Should You Be Implementing the Organic Rankine Cycle?

[:en]To have a successful application of an ORC system, the availability of an adequate heat source is crucial. In principal every heat-generating process, such as burning fossil fuel, can be taken as a heat source for ORC.

However, the aim is to improve energy efficiency and sustainability of new or existing applications with the focus on waste heat and renewable energy sources.

Three sectors have been identified as potential sources for the application of ORC power generation: Continue reading “Should You Be Implementing the Organic Rankine Cycle?”

Cavitation Problems

[:en]Cavitation is not welcome in pumps. One of the most problematic effects of cavitation is the reduction in performance, but this is not the only problem! Cavitation can also cause damage to blades and create noise while the pump is working.

Perhaps, the most universal problem caused by cavitation is the material damage that bubbles can cause when they collapse in the vicinity of a solid surface. The problem is complex because it involves the details of a complicated unsteady flow combined with the reaction of the particular blade material. Continue reading “Cavitation Problems”

Axial and Mixed Pump Theory

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Axial Pump
Axial Pump

Unlike the centrifugal pump, the performance in axial machines is a function of the action of the blade profiles. Because of this, the main approach in design of axial pumps is focused on blade performance.

Impeller blades of axial flow pumps have a double curvature form at the inlet and at the outlet due to the change in diameter from hub to periphery. Absolute flow before and after the impeller and relative flow along the impeller passage are axisymmetric and potential. There is no radial mixing. Under this condition, each streamline is parallel to the axis of the pump. Fluid passes parallel to the pump axis i.e., along the streamline. Continue reading “Axial and Mixed Pump Theory”

Criteria for Selecting Pumps – Specific Speed

[:en]We had a great week last week with our Steam and Gas Turbine Design workshop and we thank all of our participants who joined us in Boston and Zug, Switzerland! But like any rotating turbomachinery company, we’re rotating right along into another topic, pumps.

As with any turbomachine, when you’re in the process of selection, you should take into account a few factors depending on the application.

The specific speed should be the first parameter to take into account when designing and installing a new pump. Continue reading “Criteria for Selecting Pumps – Specific Speed”

A Common Debate: Axial or Radial Turbine?

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Comparison of efficiency against power output for axial flow and radial inflow turbine configuration
Comparison of efficiency against power output for axial flow and radial inflow turbine configuration

The question always remains, which is better: axial or radial? But with that question are sub questions: Which application? Which fluid? What results are you looking for exactly?

In automobiles for waste heat recovery, we believe that radial inflow turbines are more suited for use. Here’s why:

Continue reading “A Common Debate: Axial or Radial Turbine?”

3 Categories and Sources of Vibrations

[:en]In view of the large number of blades in any turbine machine, the existence of unavoidable sources of vibration excitation and the serious consequences of the failure of just one blade, an intimate knowledge and understanding of the vibration characteristics of the blades in their operating environment is essential.

Vibration excitation can arise from a variety of sources but principally involves the following categories: Continue reading “3 Categories and Sources of Vibrations”