Integrated Thermostatic Modulation "Controllable Variable Flow "

Basics of Operation

Adjustable inlet guide vanes provide the variable directional pre-swirl which modulates the pump corresponding to the provided control signal and associated calibration strategy.   
The vanes are arranged around the pump impeller inlet so that they impart either a positive or negative pre-swirl into the impeller as they actuate in response to thermal demand.  Additionally, the vanes close to provide the radiator valve function which in the conventional systems of today is provided by a conventional thermostat.

With increasing coolant control temperature the vanes adjust to provide increased flow and conversely when thermal demand lessens as for part-load and low ambient driving conditions, the vanes adjust to reduce the pump output..


Technology Background

The use of variable inlet guide vanes to provide pre-swirl has long been recognized as the most efficient method of achieving variable output for turbo-machinery applications including Kaplan and Francis turbines, and variable geometry turbochargers to name a few.

Conventional thermostats employed in today's automotive systems throttle flow through the radiator and bypass circuits, but do not vary the pump's capacity.

Compare a Conventional Cooling System
to the FloWork System

Operation Comparison

The angles α1 and α2 shown in figures 1 and 2 express the tangential components of the absolute velocity vectors, Vt1 and Vt2 . The inlet component Vt1 , written as Vt1 = V1 cos α1 describes the amount and direction of inlet pre-swirl.

Figure 2 shows the entry speed vector triangles for three cases.

The triangles in figure 2 show the relative effect of the inlet angle α1 on the entry vector Vt1 .  So, the magnitude of α1 denotes the effect of the inlet preswirl (or pre-rotation) on the Head, and Velocity vector product which is proportional to Flow.  For example when α1 = 90 degrees (no preswirl), Vt1 = zero.   Similarly for α1 < 90° the sign is negative, effectively reducing the pump Flow and Head output, and conversely for α1 > 90° the pump Head (and Flow) output is increased.

 The resulting impact of pump performance is shown in figure 3, which depicts several different pump performance characteristics for variable inlet guide vane positions. 

Prevents Onset of Cavitation

This important benefit results from providing an additional modulation parameter for coolant flow and pressure output. When higher temperature is sensed, the Flowork pump increases flow and pressure output, thus preventing the onset of cavitation which would otherwise occur at a given fluid temperature without increased flow and pressure.

thermal flow control technology
variable flow control pump

Animation showing the two primary operating modes


flow mode change


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