Patent Publication Number: US-2006018753-A1

Title: High pressure tandem turbine

Description:
CROSS-REFERENCE TO RELATED APPPLICATION  
      This application claims the benefit of Provisional application Ser. No. 60/590,044, filed Jul. 20, 2004. 
    
    
     FEDERALLY SPONSORED RESEARCH  
      Not Applicable  
     SEQUENCE LISTING OR PROGRAM  
      Not Applicable  
     BACKGROUND  
      The present invention relates to an improved apparatus used for moving gases or air for the purposes of either causing a vacuum upstream as in vacuum pumps or high-pressure downstream as in industrial blowers, turbochargers for automotive engines, ducted fan propulsion devices, and compressors for gas turbines.  
      The practical compression ratio of a typical single stage axial blower is limited approximately to 1.4 to 1.0. To improve this ratio, a typical axial flow gas turbine engine compressor utilizes a series of rotors followed by non-rotating fixed blades, commonly known as stators. Some gas turbines utilize up to 18 sets of rotors and 18 sets of stators to achieve the desired compression ratio. This high number of components makes the overall engine very complex, adding to the number of moving parts and adding the necessity of numerous seals between the stators and the rotors. Each added part adds to the size, weight, complexity, cost and reduced efficiency of the apparatus due to the increased high-speed frictional surface area. Ultimately this results in engines vulnerable to failure.  
      In radial flow (centrifugal) compressors, the same magnitude of compression may be theoretically achieved by stacking rotors in sequence and with much higher rotational speeds. However, high speeds limit the geometry of the axial compressor design. A high-speed radial flow compressor with anything but a perfectly radial compressor tail fin section will fail due to induced vibrations and centrifugal forces. Stacking in these designs also require cumbersome housing configurations, which add weight and inefficiency.  
      Although, the following prior art describes improvements related to turbo and gas turbine engines, none of them discloses the specific improvement that the present invention embodies. U.S. Pat. No. 4,512,718 to Stargardter describes a fan rotor assembly for gas turbine engines having decreased susceptibility to vibratory damage. U.S. Pat. No. 5,984,631 to Tolgos presents a tandem turbine-blade cascade for a turbine, turbo-engine or power engine that includes at least two rows of blades disposed substantially directly in line with one another in the rotor or stator. While this art improves over previous designs by reducing the overall number of stages, it is still intended for multiple stages. As a single stage, it could never achieve the high-pressure ratios of the present invention and still maintain sub-sonic blade-tip velocities. Hence, it is a principle object of the present invention to overcome the problems and deficiencies in the art.  
      It is an object of the present invention to provide an improved apparatus used for moving gases or air in a single stage, for the purposes of either causing vacuum upstream as in vacuum pumps or high-pressure downstream as in industrial blowers, turbochargers for automotive engines, ducted fan propulsion devices, and compressors for gas turbines.  
      It is another object of the present invention to provide an apparatus that results in an improvement in both efficiency and output over radial flow (centrifugal) compressors.  
      Still another object of the invention is to provide an apparatus wherein two matching sets of rotor vanes are paired and rotate in the same direction, whereby said apparatus does not comprise of a stator between the two sets of rotors and thereby can yield extremely high-pressure ratios, sufficient even for a jet engine.  
      A further object of the invention is to provide an apparatus wherein the first and second set of paired rotor blades have continuous and progressive pitch angles, the same number of blades, and are designed to complement each other.  
      A further object of the invention is to provide a single stage apparatus wherein the first and second set of blades are joined to form a complete single sweep with forward facing trailing ends with or without blunt termination.  
      These and other objects will become apparent from the following accompanying drawings and description.  
     SUMMARY  
      The present invention relates to an improved apparatus used for moving gases or air in a single stage for the purposes of either causing a vacuum upstream as in vacuum pumps or high-pressure downstream as in industrial blowers, turbochargers for automotive engines, ducted fan propulsion devices, and compressors for gas turbines. It has been found that by pairing two matching sets of rotor vanes, rotating in the same direction, without a stator between the two sets of rotors, can yield extreme high-pressure ratios.  
      In the improved concept, the first and second set of rotor blades are paired, having continuous and progressive pitch angles and the same number of blades designed to complement each other as opposed to each set performing a consecutive or similar operation as in the present state of the art. In certain cases, where extreme high exit velocities are desired without high pressure requirements, as in a leaf blower, ducted-fan propulsion device or a blower used as a cooling device, a single sweep turbo as outlined by  FIG. 5  may be used.  
    
    
     BREIF DESCRIPTION OF THE FIGURES  
       FIG. 1  is an isometric perspective view illustrating the arrangements of two sets of rotor blades on a common hub in accordance with the present invention.  
       FIG. 2  is a side view showing the end view geometry of the blades attached to a typical common hub.  
       FIG. 3  illustrates the vector analysis of a tandem turbo of the present invention.  
       FIG. 4  is a pictorial representation of the airflow pattern departing chaser blades in accordance with the present invention.  
       FIG. 5  is a side view showing the end view of the single sweep blade attached to a common hub. 
    
    
     FIGURES—REFERENCE NUMBERS  
     
         
           10  . . . High Pressure Tandem Turbo  
           11  . . . Hub  
           12  . . . Chaser Blade  
           13  . . . Leading Blade  
           14  . . . Accelerated Particles  
           100  . . . Apparent Entry Velocity  
           101  . . . Intervace Exit/Entry Velocity  
           102  . . . Axial Velocity  
           103  . . . Chaser Blade Exit Velocity  
           104  . . . Apparent Exit Velocity  
           105  . . . Radial Velocity at Mean Blade Radius  
           106  . . . Degree of Reaction at leading blade  
           107  . . . Degree of Reaction at chasing blade  
       
    
     DETAILED DESCRIPTION  
      The embodiments of the present invention are illustrated as shown in  FIGS. 1 through 5 . The present invention relates to an improved apparatus  10  used for moving gases or air in a single stage for the purposes of either causing a vacuum upstream as in vacuum pumps or high-pressure downstream as in industrial blowers, turbochargers for automotive engines, ducted fan propulsion devices, and compressors for gas turbines. It has been found that pairing two matching sets of rotor vanes as illustrated by the figures herein, rotating in the same direction, without a stator between the two sets of rotors, can yield extreme high-pressure ratios, sufficient even for jet engines.  
      In the improved concept, the leading set of rotor blades  13  and chasing set of rotor blades  12  are paired, having continuous and progressive pitch angles, the same number of blades, designed to complement each other as opposed to having each set perform a consecutive or concerted operation as disclosed in the present state of the art. The matching sets of rotor blades are not merely stacked duplicate propeller blades. Rather, they operate at different angles designed to compliment each other. In fact, the chaser blades  12  may not even be functional as fluid moving devices by themselves. They require the leading blades  13  to function in a team effort.  
      The blades work in pairs much like a tag team; the function of the leading blade  13  is to induce airflow to the chaser blade  12  and to prevent the chaser blade  12  from stalling by controlling the boundary layer. This is achieved by advancing the chaser blade  12  ahead of the leading blade  13  to provide a high-energy stream from the high-pressure side of the leading blade  13  to the low-pressure side of the chaser blade  12 . The degree of advance is based on the dynamic boundary layer thickness and the magnitude of work done, i.e., pressure ratios. The leading edge  13  blade in turn benefits from the chaser blade  12  by discharging a portion of the fluid behind the low-pressure side of the chaser blade  12 , thereby delaying the choking or cavitation point of the system.  
      As demonstrated by the figures and illustrations, the leading blade  13  is depicted as having streamlined cross section, tapering off toward its leading and trailing edges. However the trailing blade  12  may have either a streamlined or cleaver like super-cavitating type cross-section depending on the exit velocity of the fluid. While two sets of rotor blades are normally sufficient, a third or even fourth set of matching blades can be configured. In this case, each additional layer would interface with the following layer in the same manner, i.e., a small portion of the high energy fluid stream would be directed at the low pressure side of the following blade to prevent boundary layer separation in the following or the chaser blade  12 .  
      Referring to the drawings, in both  FIGS. 1 and 2 , the blades are shown as integral part of the entire apparatus  10 . This suggests that the blades along with the hub  11  are machined from a common solid bar or made by an investment casting or similar high precision casting or powder metal process. However, the blades can also be individual elements attached and locked to a common hub by means of dovetail or other fastening methods.  
      The chaser blade&#39;s  12  function is clearly visible by lines  101 ,  103 , and  104  as seen in  FIG. 3 . The marked angle  106  represents the degree of reaction at the leading blade. The marked angle  107  represents the degree of reaction at the chaser blade leading to an angular exit velocity represented by line  104 .  
      The present invention can also be operated with a progressive cavity housing behind the chaser blades, leading to a tangential exit outlet as illustrated by  FIG. 4 , where greatly accelerated particles  14  exit the chaser blade  12  at high velocity. A side-view of the single sweep bladed turbo is shown in  FIG. 5 , illustrating how the leading blade, chaser blade, and hub are aligned, and therefore how the blades affect the airflow pattern departing the chaser blades  12 .  
      Although preferred embodiments of the present invention have been shown and described, various modifications and substitutions may be made thereto without departing from the spirit and scope of the invention. Accordingly, it is to be understood that the present invention has been described by way of illustration and not limitation.  
      The present invention relates to an improved apparatus used for moving gases or air for the purposes of either causing a vacuum upstream as in vacuum pumps or high-pressure downstream as in industrial blowers, turbochargers for automotive engines, ducted fan propulsion devices, and compressors for gas turbines.  
      In the present invention, it has been found that pairing two matching sets of rotor vanes rotating in the same direction, without a stator between the two sets of rotors, in a single stage, can yield extreme high-pressure ratios.  
      The first and second set of rotor blades that are paired have continuous and progressive pitch angles, the same number of blades, and are designed to complement each other.  
      The present invention is also an improvement in both efficiency and output over radial flow (centrifugal) compressors.  
      Although the description above contains much specificity, it should not be construed as limiting the scope of the invention but as merely providing illustrations of some of the presently preferred embodiments of this invention. Thus, the scope of the invention should be determined by the appended claims and their legal equivalents, rather than by the examples given.