Cavitation Problems

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

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

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”

Carryover Losses – Steam and Gas Turbines

losses
Losses

A number of loss prediction methods exist in turbomachines. Concerning axial turbines, there are at least seven methods just for cascade losses! But there are also loss models developed to predict individual loss components such as secondary, seal and tip clearance losses and more.

Of course depending on the machine and application type, some of the models are more or less applicable to specific cases. But ff the different types of auxiliary losses, which are losses that do not belong to blade cascades and can be classified as whole stage, there are carryover losses.

Continue reading “Carryover Losses – Steam and Gas Turbines”

What’s An Ideal Heat Engine Cycle?

The Carnot cycle is the most efficient cycle possible for converting a given amount of thermal energy into work or, conversely, for using a given amount of work for refrigeration purposes.

Every thermodynamic system exists in a particular state. A thermodynamic cycle occurs when a system is taken through a series of different states, and finally returned to its initial state. In the process of going through this cycle, the system may perform work on its surroundings, thereby acting as a heat engine. Continue reading “What’s An Ideal Heat Engine Cycle?”

Calculating Sections in Steam Turbines

9 Section Axial Steam Turbine
9 Section Axial Steam Turbine

What’s a better way to begin our brand new turbomachinery blog then by addressing a common design question about something we are very familiar with – steam turbines?

Many times the question, “How many calculation sections do you recommend for the (insert any number here)-stage steam turbine?” travels through our tech support emails and we always answer our clients with what we think is best practice. Continue reading “Calculating Sections in Steam Turbines”

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